1. # Redis configuration file example
    3. # Note on units: when memory size is needed, it is possible to specify
    4. # it in the usual form of 1k 5GB 4M and so forth:
    5. #在配置文件的开头部分,首先明确了一些度量单位
    6. # 1k => 1000 bytes
    7. # 1kb => 1024 bytes
    8. # 1m => 1000000 bytes
    9. # 1mb => 1024*1024 bytes
    10. # 1g => 1000000000 bytes
    11. # 1gb => 1024*1024*1024 bytes
    12. #可以看出，redis配置中对单位的大小写不敏感,1GB,1Gb和1gB都是相同的.由此也说明,redis只支持bytes,
    13. #不支持bit单位
    14. # units are case insensitive so 1GB 1Gb 1gB are all the same.
    16. ################################## INCLUDES ###################################
    18. # Include one or more other config files here.  This is useful if you
    19. # have a standard template that goes to all Redis servers but also need
    20. # to customize a few per-server settings.  Include files can include
    21. # other files, so use this wisely.
    22. #
    23. # Notice option "include" won't be rewritten by command "CONFIG REWRITE"
    24. # from admin or Redis Sentinel. Since Redis always uses the last processed
    25. # line as value of a configuration directive, you'd better put includes
    26. # at the beginning of this file to avoid overwriting config change at runtime.
    27. #
    28. # If instead you are interested in using includes to override configuration
    29. # options, it is better to use include as the last line.
    30. #redis支持“主配置文件中引入外部配置文件”,很像C/C++中的include指令，比如
    31. # include .\path\to\local.conf
    32. # include c:\path\to\other.conf
    34. #如果你看过redis的配置文件，会发现还是很有条理的。redis配置文件被分成了几大块区域，它们分别是:
    35. #1.通用（general）
    36. #2.快照（snapshotting）
    37. #3.复制（replication）
    38. #4.安全（security）
    39. #5.限制（limits)
    40. #6.追加模式（append only mode)
    41. #7.LUA脚本（lua scripting)
    42. #8.慢日志（slow log)
    43. #9.事件通知（event notification）
    44. ################################ GENERAL  #####################################
    46. # On Windows, daemonize and pidfile are not supported.
    47. # However, you can run redis as a Windows service, and specify a logfile.
    48. # The logfile will contain the pid. 
    50. # Accept connections on the specified port, default is 6379.
    51. # If port 0 is specified Redis will not listen on a TCP socket.
    52. #redis的默认服务端口是6379,你可以通过port配置项来修改.如果端口设置为0的话,redis便不会监听端口了.
    53. port 6379
    55. # TCP listen() backlog.
    56. #
    57. # In high requests-per-second environments you need an high backlog in order
    58. # to avoid slow clients connections issues. Note that the Linux kernel
    59. # will silently truncate it to the value of /proc/sys/net/core/somaxconn so
    60. # make sure to raise both the value of somaxconn and tcp_max_syn_backlog
    61. # in order to get the desired effect.
    62. tcp-backlog 511
    64. # By default Redis listens for connections from all the network interfaces
    65. # available on the server. It is possible to listen to just one or multiple
    66. # interfaces using the "bind" configuration directive, followed by one or
    67. # more IP addresses.
    68. #
    69. # Examples:
    70. #默认情况下，redis会响应本机所有可用网卡的连接请求。
    71. #当然，redis允许你通过bind配置项来指定要绑定的IP，比如：
    72. # bind 192.168.1.100 10.0.0.1
    73. # bind 127.0.0.1
    76. # Specify the path for the Unix socket that will be used to listen for
    77. # incoming connections. There is no default, so Redis will not listen
    78. # on a unix socket when not specified.
    79. ##有些同学会问“如果redis不监听端口，还怎么与外界通信呢”，其实redis还支持通过unix socket方式来接收请求。
    80. #可以通过unixsocket配置项来指定unix socket文件的路径，并通过unixsocketperm来指定文件的权限
    81. # unixsocket /tmp/redis.sock
    82. # unixsocketperm 700
    84. # Close the connection after a client is idle for N seconds (0 to disable)
    85. #当一个redis-client一直没有请求发向server端,那么server端有权主动关闭这个连接,
    86. #可以通过timeout来设置“空闲超时时限”,0表示永不关闭
    87. timeout 0
    89. # TCP keepalive.
    90. #
    91. # If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence
    92. # of communication. This is useful for two reasons:
    93. #
    94. # 1) Detect dead peers.
    95. # 2) Take the connection alive from the point of view of network
    96. #    equipment in the middle.
    97. #
    98. # On Linux, the specified value (in seconds) is the period used to send ACKs.
    99. # Note that to close the connection the double of the time is needed.
    100. # On other kernels the period depends on the kernel configuration.
    101. #
    102. # A reasonable value for this option is 60 seconds.
    103. #TCP连接保活策略，可以通过tcp-keepalive配置项来进行设置,单位为秒,假如设置为60秒,
    104. #则server端会每60秒向连接空闲的客户端发起一次ACK请求,以检查客户端是否已经挂掉,
    105. #对于无响应的客户端则会关闭其连接.所以关闭一个连接最长需要120秒的时间.如果设置为0,则不会进行保活检测.
    106. tcp-keepalive 0
    108. # Specify the server verbosity level.
    109. # This can be one of:
    110. # debug (a lot of information, useful for development/testing)
    111. # verbose (many rarely useful info, but not a mess like the debug level)
    112. # notice (moderately verbose, what you want in production probably)
    113. # warning (only very important / critical messages are logged)
    114. #redis支持通过loglevel配置项设置日志等级,共分四级,即debug、verbose、notice、warning
    115. loglevel notice
    117. # Specify the log file name. Also 'stdout' can be used to force
    118. # Redis to log on the standard output. 
    119. #redis也支持通过logfile配置项来设置日志文件的生成位置.如果设置为空字符串,则redis会将日志输出到标准输出.
    120. #假如你在daemon情况下将日志设置为输出到标准输出,则日志会被写到/dev/null中.
    121. logfile ""
    123. # To enable logging to the Windows EventLog, just set 'syslog-enabled' to 
    124. # yes, and optionally update the other syslog parameters to suit your needs.
    125. # If Redis is installed and launched as a Windows Service, this will 
    126. # automatically be enabled.
    127. # syslog-enabled no
    128. #如果希望日志打印到syslog中,也很容易,通过syslog-enabled来控制.
    130. #另外,syslog-ident还可以让你指定syslog里的日志标志,比如：
    131. # Specify the source name of the events in the Windows Application log.
    132. # syslog-ident redis
    134. # Set the number of databases. The default database is DB 0, you can select
    135. # a different one on a per-connection basis using SELECT <dbid> where
    136. # dbid is a number between 0 and 'databases'-1
    137. #对于redis来说，可以设置其数据库的总数量，假如你希望一个redis包含16个数据库，那么设置如下：
    138. databases 16
    140. ################################ SNAPSHOTTING  ################################
    141. #快照，主要涉及的是redis的RDB持久化相关的配置，我们来一起看一看。
    142. #
    143. #我们可以用如下的指令来让数据保存到磁盘上，即控制RDB快照功能：
    144. # Save the DB on disk:
    145. #
    146. #   save <seconds> <changes>
    147. #
    148. #   Will save the DB if both the given number of seconds and the given
    149. #   number of write operations against the DB occurred.
    150. #
    151. #   In the example below the behaviour will be to save:
    152. #   after 900 sec (15 min) if at least 1 key changed
    153. #   after 300 sec (5 min) if at least 10 keys changed
    154. #   after 60 sec if at least 10000 keys changed
    155. #
    156. #   Note: you can disable saving completely by commenting out all "save" lines.
    157. #
    158. #   It is also possible to remove all the previously configured save
    159. #   points by adding a save directive with a single empty string argument
    160. #   like in the following example:
    161. #如果你想禁用RDB持久化的策略，只要不设置任何save指令就可以，
    162. #或者给save传入一个空字符串参数也可以达到相同效果，就像这样：
    163. #   save ""
    165. save 900 1 //表示每15分钟且至少有1个key改变，就触发一次持久化
    166. save 300 10 //表示每5分钟且至少有10个key改变，就触发一次持久化
    167. save 60 10000 //表示每60秒至少有10000个key改变，就触发一次持久化
    169. # By default Redis will stop accepting writes if RDB snapshots are enabled
    170. # (at least one save point) and the latest background save failed.
    171. # This will make the user aware (in a hard way) that data is not persisting
    172. # on disk properly, otherwise chances are that no one will notice and some
    173. # disaster will happen.
    174. #如果用户开启了RDB快照功能,那么在redis持久化数据到磁盘时如果出现失败,
    175. #默认情况下,redis会停止接受所有的写请求.这样做的好处在于可以让用户很明确的知道内存中的
    176. #数据和磁盘上的数据已经存在不一致了.如果redis不顾这种不一致,一意孤行的继续接收写请求,
    177. #就可能会引起一些灾难性的后果.
    178. # If the background saving process will start working again Redis will
    179. # automatically allow writes again.
    180. #如果下一次RDB持久化成功，redis会自动恢复接受写请求。
    181. # However if you have setup your proper monitoring of the Redis server
    182. # and persistence, you may want to disable this feature so that Redis will
    183. # continue to work as usual even if there are problems with disk,
    184. # permissions, and so forth.
    185. #当然，如果你不在乎这种数据不一致或者有其他的手段发现和控制这种不一致的话，
    186. #你完全可以关闭这个功能，以便在快照写入失败时，也能确保redis继续接受新的写请求。配置项如下：
    187. stop-writes-on-bgsave-error yes
    189. # Compress string objects using LZF when dump .rdb databases?
    190. # For default that's set to 'yes' as it's almost always a win.
    191. # If you want to save some CPU in the saving child set it to 'no' but
    192. # the dataset will likely be bigger if you have compressible values or keys.
    193. #对于存储到磁盘中的快照,可以设置是否进行压缩存储.如果是的话,redis会采用LZF算法进行压缩.
    194. #如果你不想消耗CPU来进行压缩的话,可以设置为关闭此功能,但是存储在磁盘上的快照会比较大.
    195. rdbcompression yes
    197. # Since version 5 of RDB a CRC64 checksum is placed at the end of the file.
    198. # This makes the format more resistant to corruption but there is a performance
    199. # hit to pay (around 10%) when saving and loading RDB files, so you can disable it
    200. # for maximum performances.
    201. #在存储快照后，我们还可以让redis使用CRC64算法来进行数据校验，
    202. #但是这样做会增加大约10%的性能消耗，如果你希望获取到最大的性能提升，可以关闭此功能。
    203. #
    204. # RDB files created with checksum disabled have a checksum of zero that will
    205. # tell the loading code to skip the check.
    206. rdbchecksum yes
    208. # The filename where to dump the DB
    209. #我们还可以设置快照文件的名称，默认是这样配置的：
    210. dbfilename dump.rdb
    212. # The working directory.
    213. #
    214. # The DB will be written inside this directory, with the filename specified
    215. # above using the 'dbfilename' configuration directive.
    216. # 
    217. # The Append Only File will also be created inside this directory.
    218. # 
    219. # Note that you must specify a directory here, not a file name.
    220. #最后，你还可以设置这个快照文件存放的路径。比如默认设置就是当前文件夹：
    221. dir ./
    223. ################################# REPLICATION #################################
    225. # Master-Slave replication. Use slaveof to make a Redis instance a copy of
    226. # another Redis server. A few things to understand ASAP about Redis replication.
    227. #
    228. # 1) Redis replication is asynchronous, but you can configure a master to
    229. #    stop accepting writes if it appears to be not connected with at least
    230. #    a given number of slaves.
    231. # 2) Redis slaves are able to perform a partial resynchronization with the
    232. #    master if the replication link is lost for a relatively small amount of
    233. #    time. You may want to configure the replication backlog size (see the next
    234. #    sections of this file) with a sensible value depending on your needs.
    235. # 3) Replication is automatic and does not need user intervention. After a
    236. #    network partition slaves automatically try to reconnect to masters
    237. #    and resynchronize with them.
    238. #redis提供了主从同步功能。
    239. #通过slaveof配置项可以控制某一个redis作为另一个redis的从服务器，通过指定IP和端口来定位到主redis的位置。
    240. #一般情况下，我们会建议用户为从redis设置一个不同频率的快照持久化的周期，或者为从redis配置一个不同的
    241. #服务端口等等
    242. # slaveof <masterip> <masterport>
    244. # If the master is password protected (using the "requirepass" configuration
    245. # directive below) it is possible to tell the slave to authenticate before
    246. # starting the replication synchronization process, otherwise the master will
    247. # refuse the slave request.
    248. #如果主redis设置了验证密码的话（使用requirepass来设置），则在从redis的配置中要使用masterauth来
    249. #设置校验密码,否则的话，主redis会拒绝从redis的访问请求。
    250. # masterauth <master-password>
    252. # When a slave loses its connection with the master, or when the replication
    253. # is still in progress, the slave can act in two different ways:
    254. #当从redis失去了与主redis的连接，或者主从同步正在进行中时，redis该如何处理外部发来的访问请求呢？
    255. #这里，从redis可以有两种选择：
    256. # 1) if slave-serve-stale-data is set to 'yes' (the default) the slave will
    257. #    still reply to client requests, possibly with out of date data, or the
    258. #    data set may just be empty if this is the first synchronization.
    259. #第一种选择:如果slave-serve-stale-data设置为yes（默认），则从redis仍会继续响应客户端的读写请求。
    261. # 2) if slave-serve-stale-data is set to 'no' the slave will reply with
    262. #    an error "SYNC with master in progress" to all the kind of commands
    263. #    but to INFO and SLAVEOF.
    264. #第二种选择:如果slave-serve-stale-data设置为no，则从redis会对客户端的
    265. #请求返回“SYNC with master in progress”，当然也有例外，当客户端发来INFO请求和SLAVEOF请求，
    266. #从redis还是会进行处理。
    267. #
    268. slave-serve-stale-data yes
    270. # You can configure a slave instance to accept writes or not. Writing against
    271. # a slave instance may be useful to store some ephemeral data (because data
    272. # written on a slave will be easily deleted after resync with the master) but
    273. # may also cause problems if clients are writing to it because of a
    274. # misconfiguration.
    275. #
    276. # Since Redis 2.6 by default slaves are read-only.
    277. #
    278. # Note: read only slaves are not designed to be exposed to untrusted clients
    279. # on the internet. It's just a protection layer against misuse of the instance.
    280. # Still a read only slave exports by default all the administrative commands
    281. # such as CONFIG, DEBUG, and so forth. To a limited extent you can improve
    282. # security of read only slaves using 'rename-command' to shadow all the
    283. # administrative / dangerous commands.
    284. #你可以控制一个从redis是否可以接受写请求。将数据直接写入从redis，一般只适用于那些生命周期
    285. #非常短的数据，因为在主从同步时，这些临时数据就会被清理掉。自从redis2.6版本之后，默认从redis为只读。
    286. slave-read-only yes
    288. # Replication SYNC strategy: disk or socket.
    289. #
    290. # -------------------------------------------------------
    291. # WARNING: DISKLESS REPLICATION IS EXPERIMENTAL CURRENTLY
    292. # -------------------------------------------------------
    293. #
    294. # New slaves and reconnecting slaves that are not able to continue the replication
    295. # process just receiving differences, need to do what is called a "full
    296. # synchronization". An RDB file is transmitted from the master to the slaves.
    297. # The transmission can happen in two different ways:
    298. #
    299. # 1) Disk-backed: The Redis master creates a new process that writes the RDB
    300. #                 file on disk. Later the file is transferred by the parent
    301. #                 process to the slaves incrementally.
    302. # 2) Diskless: The Redis master creates a new process that directly writes the
    303. #              RDB file to slave sockets, without touching the disk at all.
    304. #
    305. # With disk-backed replication, while the RDB file is generated, more slaves
    306. # can be queued and served with the RDB file as soon as the current child producing
    307. # the RDB file finishes its work. With diskless replication instead once
    308. # the transfer starts, new slaves arriving will be queued and a new transfer
    309. # will start when the current one terminates.
    310. #
    311. # When diskless replication is used, the master waits a configurable amount of
    312. # time (in seconds) before starting the transfer in the hope that multiple slaves
    313. # will arrive and the transfer can be parallelized.
    314. #
    315. # With slow disks and fast (large bandwidth) networks, diskless replication
    316. # works better.
    317. repl-diskless-sync no
    319. # When diskless replication is enabled, it is possible to configure the delay
    320. # the server waits in order to spawn the child that transfers the RDB via socket
    321. # to the slaves.
    322. #
    323. # This is important since once the transfer starts, it is not possible to serve
    324. # new slaves arriving, that will be queued for the next RDB transfer, so the server
    325. # waits a delay in order to let more slaves arrive.
    326. #
    327. # The delay is specified in seconds, and by default is 5 seconds. To disable
    328. # it entirely just set it to 0 seconds and the transfer will start ASAP.
    329. repl-diskless-sync-delay 5
    331. # Slaves send PINGs to server in a predefined interval. It's possible to change
    332. # this interval with the repl_ping_slave_period option. The default value is 10
    333. # seconds.
    334. #从redis会周期性的向主redis发出PING包。你可以通过repl_ping_slave_period指令来控制其周期。默认是10秒。
    335. # repl-ping-slave-period 10
    337. # The following option sets the replication timeout for:
    338. #
    339. # 1) Bulk transfer I/O during SYNC, from the point of view of slave.
    340. # 2) Master timeout from the point of view of slaves (data, pings).
    341. # 3) Slave timeout from the point of view of masters (REPLCONF ACK pings).
    342. #在主从同步时，可能在这些情况下会有超时发生：
    343. #1.以从redis的角度来看，当有大规模IO传输时。
    344. #2.以从redis的角度来看，当数据传输或PING时，主redis超时
    345. #3.以主redis的角度来看，在回复从redis的PING时，从redis超时
    347. # It is important to make sure that this value is greater than the value
    348. # specified for repl-ping-slave-period otherwise a timeout will be detected
    349. # every time there is low traffic between the master and the slave.
    350. #用户可以设置上述超时的时限，不过要确保这个时限比repl-ping-slave-period的值要大，
    351. #否则每次主redis都会认为从redis超时。
    352. # repl-timeout 60
    354. # Disable TCP_NODELAY on the slave socket after SYNC?
    355. #
    356. # If you select "yes" Redis will use a smaller number of TCP packets and
    357. # less bandwidth to send data to slaves. But this can add a delay for
    358. # the data to appear on the slave side, up to 40 milliseconds with
    359. # Linux kernels using a default configuration.
    360. #
    361. # If you select "no" the delay for data to appear on the slave side will
    362. # be reduced but more bandwidth will be used for replication.
    363. #
    364. # By default we optimize for low latency, but in very high traffic conditions
    365. # or when the master and slaves are many hops away, turning this to "yes" may
    366. # be a good idea.
    367. #我们可以控制在主从同步时是否禁用TCP_NODELAY。如果开启TCP_NODELAY，
    368. #那么主redis会使用更少的TCP包和更少的带宽来向从redis传输数据。
    369. #但是这可能会增加一些同步的延迟，大概会达到40毫秒左右。如果你关闭了TCP_NODELAY，
    370. #那么数据同步的延迟时间会降低，但是会消耗更多的带宽。
    371. repl-disable-tcp-nodelay no
    373. # Set the replication backlog size. The backlog is a buffer that accumulates
    374. # slave data when slaves are disconnected for some time, so that when a slave
    375. # wants to reconnect again, often a full resync is not needed, but a partial
    376. # resync is enough, just passing the portion of data the slave missed while
    377. # disconnected.
    378. #
    379. # The bigger the replication backlog, the longer the time the slave can be
    380. # disconnected and later be able to perform a partial resynchronization.
    381. #
    382. # The backlog is only allocated once there is at least a slave connected.
    383. #我们还可以设置同步队列长度。队列长度（backlog)是主redis中的一个缓冲区，
    384. #在与从redis断开连接期间，主redis会用这个缓冲区来缓存应该发给从redis的数据。
    385. #这样的话，当从redis重新连接上之后，就不必重新全量同步数据，只需要同步这部分增量数据即可。
    386. # repl-backlog-size 1mb
    388. # After a master has no longer connected slaves for some time, the backlog
    389. # will be freed. The following option configures the amount of seconds that
    390. # need to elapse, starting from the time the last slave disconnected, for
    391. # the backlog buffer to be freed.
    392. #
    393. # A value of 0 means to never release the backlog.
    394. #如果主redis等了一段时间之后，还是无法连接到从redis，那么缓冲队列中的数据将被清理掉。
    395. #我们可以设置主redis要等待的时间长度。如果设置为0，则表示永远不清理。默认是1个小时。
    396. # repl-backlog-ttl 3600
    398. # The slave priority is an integer number published by Redis in the INFO output.
    399. # It is used by Redis Sentinel in order to select a slave to promote into a
    400. # master if the master is no longer working correctly.
    401. #
    402. # A slave with a low priority number is considered better for promotion, so
    403. # for instance if there are three slaves with priority 10, 100, 25 Sentinel will
    404. # pick the one with priority 10, that is the lowest.
    405. #
    406. # However a special priority of 0 marks the slave as not able to perform the
    407. # role of master, so a slave with priority of 0 will never be selected by
    408. # Redis Sentinel for promotion.
    409. #我们可以给众多的从redis设置优先级，在主redis持续工作不正常的情况，优先级高的从redis
    410. #将会升级为主redis。而编号越小，优先级越高。比如一个主redis有三个从redis，
    411. #优先级编号分别为10、100、25，那么编号为10的从redis将会被首先选中升级为主redis。
    412. #当优先级被设置为0时，这个从redis将永远也不会被选中。默认的优先级为100。
    413. # By default the priority is 100.
    414. slave-priority 100
    416. # It is possible for a master to stop accepting writes if there are less than
    417. # N slaves connected, having a lag less or equal than M seconds.
    418. #
    419. # The N slaves need to be in "online" state.
    420. #
    421. # The lag in seconds, that must be <= the specified value, is calculated from
    422. # the last ping received from the slave, that is usually sent every second.
    423. #
    424. # This option does not GUARANTEE that N replicas will accept the write, but
    425. # will limit the window of exposure for lost writes in case not enough slaves
    426. # are available, to the specified number of seconds.
    427. #
    428. # For example to require at least 3 slaves with a lag <= 10 seconds use:
    429. #假如主redis发现有超过M个从redis的连接延时大于N秒，那么主redis就停止接受外来的写请求。
    430. #这是因为从redis一般会每秒钟都向主redis发出PING，而主redis会记录每一个从redis
    431. #最近一次发来PING的时间点，所以主redis能够了解每一个从redis的运行情况。
    432. # min-slaves-to-write 3
    433. # min-slaves-max-lag 10
    434. #上面这个例子表示，假如有大于等于3个从redis的连接延迟大于10秒，那么主redis就不再
    435. #接受外部的写请求。上述两个配置中有一个被置为0，则这个特性将被关闭。
    436. #默认情况下min-slaves-to-write为0，而min-slaves-max-lag为10。
    437. # Setting one or the other to 0 disables the feature.
    438. #
    439. # By default min-slaves-to-write is set to 0 (feature disabled) and
    440. # min-slaves-max-lag is set to 10.
    442. ################################## SECURITY ###################################
    444. # Require clients to issue AUTH <PASSWORD> before processing any other
    445. # commands.  This might be useful in environments in which you do not trust
    446. # others with access to the host running redis-server.
    447. #
    448. # This should stay commented out for backward compatibility and because most
    449. # people do not need auth (e.g. they run their own servers).
    450. # 
    451. # Warning: since Redis is pretty fast an outside user can try up to
    452. # 150k passwords per second against a good box. This means that you should
    453. # use a very strong password otherwise it will be very easy to break.
    454. #我们可以要求redis客户端在向redis-server发送请求之前，先进行密码验证。
    455. #当你的redis-server处于一个不太可信的网络环境中时，相信你会用上这个功能。
    456. #由于redis性能非常高，所以每秒钟可以完成多达15万次的密码尝试，所以你最好设置一个足够复杂的密码，
    457. #否则很容易被黑客破解。
    458. # requirepass foobared
    460. # Command renaming.
    461. #
    462. # It is possible to change the name of dangerous commands in a shared
    463. # environment. For instance the CONFIG command may be renamed into something
    464. # hard to guess so that it will still be available for internal-use tools
    465. # but not available for general clients.
    466. #redis允许我们对redis指令进行更名，比如将一些比较危险的命令改个名字，避免被误执行。
    467. #比如可以把CONFIG命令改成一个很复杂的名字，这样可以避免外部的调用，同时还可以满足内部调用的需要：
    468. # Example:
    469. #
    470. # rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
    471. #
    472. # It is also possible to completely kill a command by renaming it into
    473. # an empty string:
    474. ##我们甚至可以禁用掉CONFIG命令，那就是把CONFIG的名字改成一个空字符串：
    475. # rename-command CONFIG ""
    476. #
    477. #但需要注意的是，如果你使用AOF方式进行数据持久化，或者需要与从redis进行通信，
    478. #那么更改指令的名字可能会引起一些问题。
    479. # Please note that changing the name of commands that are logged into the
    480. # AOF file or transmitted to slaves may cause problems.
    482. ################################### LIMITS ####################################
    484. # Set the max number of connected clients at the same time. By default
    485. # this limit is set to 10000 clients, however if the Redis server is not
    486. # able to configure the process file limit to allow for the specified limit
    487. # the max number of allowed clients is set to the current file limit
    488. # minus 32 (as Redis reserves a few file descriptors for internal uses).
    489. #我们可以设置redis同时可以与多少个客户端进行连接。默认情况下为10000个客户端。
    490. #当你无法设置进程文件句柄限制时，redis会设置为当前的文件句柄限制值减去32，
    491. #因为redis会为自身内部处理逻辑留一些句柄出来
    493. # Once the limit is reached Redis will close all the new connections sending
    494. # an error 'max number of clients reached'.
    495. #如果达到了此限制，redis则会拒绝新的连接请求，
    496. #并且向这些连接请求方发出“max number of clients reached”以作回应。
    497. # maxclients 10000
    499. # If Redis is to be used as an in-memory-only cache without any kind of
    500. # persistence, then the fork() mechanism used by the background AOF/RDB
    501. # persistence is unnecessary. As an optimization, all persistence can be
    502. # turned off in the Windows version of Redis. This will redirect heap
    503. # allocations to the system heap allocator, and disable commands that would
    504. # otherwise cause fork() operations: BGSAVE and BGREWRITEAOF.
    505. # This flag may not be combined with any of the other flags that configure
    506. # AOF and RDB operations.
    507. # persistence-available [(yes)|no]
    509. # Don't use more memory than the specified amount of bytes.
    510. # When the memory limit is reached Redis will try to remove keys
    511. # according to the eviction policy selected (see maxmemory-policy).
    512. #
    513. # If Redis can't remove keys according to the policy, or if the policy is
    514. # set to 'noeviction', Redis will start to reply with errors to commands
    515. # that would use more memory, like SET, LPUSH, and so on, and will continue
    516. # to reply to read-only commands like GET.
    517. #
    518. # This option is usually useful when using Redis as an LRU cache, or to set
    519. # a hard memory limit for an instance (using the 'noeviction' policy).
    520. #
    521. # WARNING: If you have slaves attached to an instance with maxmemory on,
    522. # the size of the output buffers needed to feed the slaves are subtracted
    523. # from the used memory count, so that network problems / resyncs will
    524. # not trigger a loop where keys are evicted, and in turn the output
    525. # buffer of slaves is full with DELs of keys evicted triggering the deletion
    526. # of more keys, and so forth until the database is completely emptied.
    527. #
    528. # In short... if you have slaves attached it is suggested that you set a lower
    529. # limit for maxmemory so that there is some free RAM on the system for slave
    530. # output buffers (but this is not needed if the policy is 'noeviction').
    531. #
    532. # WARNING: not setting maxmemory will cause Redis to terminate with an
    533. # out-of-memory exception if the heap limit is reached.
    534. #
    535. # NOTE: since Redis uses the system paging file to allocate the heap memory,
    536. # the Working Set memory usage showed by the Windows Task Manager or by other
    537. # tools such as ProcessExplorer will not always be accurate. For example, right
    538. # after a background save of the RDB or the AOF files, the working set value
    539. # may drop significantly. In order to check the correct amount of memory used
    540. # by the redis-server to store the data, use the INFO client command. The INFO
    541. # command shows only the memory used to store the redis data, not the extra
    542. # memory used by the Windows process for its own requirements. Th3 extra amount
    543. # of memory not reported by the INFO command can be calculated subtracting the
    544. # Peak Working Set reported by the Windows Task Manager and the used_memory_peak
    545. # reported by the INFO command.
    546. #如果redis无法根据移除规则来移除内存中的数据，或者我们设置了“不允许移除”，
    547. #那么redis则会针对那些需要申请内存的指令返回错误信息，比如SET、LPUSH等。
    548. #但是对于无内存申请的指令，仍然会正常响应，比如GET等。
    549. # maxmemory <bytes>
    551. #需要注意的一点是，如果你的redis是主redis（说明你的redis有从redis）,
    552. #那么在设置内存使用上限时，需要在系统中留出一些内存空间给同步队列缓存,
    553. #只有在你设置的是“不移除”的情况下，才不用考虑这个因素。
    555. # MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
    556. # is reached. You can select among five behaviors:
    557. # 对于内存移除规则来说，redis提供了多达6种的移除规则。他们是：
    558. #
    559. #1.volatile-lru：使用LRU算法移除过期集合中的key
    560. #2.allkeys-lru：使用LRU算法移除key
    561. #3.volatile-random：在过期集合中移除随机的key
    562. #4.allkeys-random：移除随机的key
    563. #5.volatile-ttl：移除那些TTL值最小的key，即那些最近才过期的key。
    564. #6.noeviction：不进行移除。针对写操作，只是返回错误信息。
    565. # volatile-lru -> remove the key with an expire set using an LRU algorithm
    566. # allkeys-lru -> remove any key according to the LRU algorithm
    567. # volatile-random -> remove a random key with an expire set
    568. # allkeys-random -> remove a random key, any key
    569. # volatile-ttl -> remove the key with the nearest expire time (minor TTL)
    570. # noeviction -> don't expire at all, just return an error on write operations
    571. # 无论使用上述哪一种移除规则，如果没有合适的key可以移除的话，redis都会针对写请求返回错误信息
    572. # Note: with any of the above policies, Redis will return an error on write
    573. #       operations, when there are no suitable keys for eviction.
    574. #
    575. #       At the date of writing these commands are: set setnx setex append
    576. #       incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd
    577. #       sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby
    578. #       zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby
    579. #       getset mset msetnx exec sort
    580. #
    581. # The default is:
    582. #
    583. # maxmemory-policy noeviction
    585. # LRU and minimal TTL algorithms are not precise algorithms but approximated
    586. # algorithms (in order to save memory), so you can select as well the sample
    587. # size to check. For instance for default Redis will check three keys and
    588. # pick the one that was used less recently, you can change the sample size
    589. # using the following configuration directive.
    590. #LRU算法和最小TTL算法都并非是精确的算法，而是估算值。所以你可以设置样本的大小。
    591. #假如redis默认会检查三个key并选择其中LRU的那个，那么你可以改变这个key样本的数量。
    592. # maxmemory-samples 3
    594. #最后，我们补充一个信息，那就是到目前版本（2.8.4）为止，redis支持的写指令包括了如下这些：
    595. #set setnx setex append
    596. #incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd
    597. #sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby
    598. #zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby
    599. #getset mset msetnx exec sort
    601. ############################## APPEND ONLY MODE ###############################
    603. # By default Redis asynchronously dumps the dataset on disk. This mode is
    604. # good enough in many applications, but an issue with the Redis process or
    605. # a power outage may result into a few minutes of writes lost (depending on
    606. # the configured save points).
    607. #默认情况下，redis会异步的将数据持久化到磁盘。这种模式在大部分应用程序中已被验证是很有效的，
    608. #但是在一些问题发生时，比如断电，则这种机制可能会导致数分钟的写请求丢失。
    609. #
    610. #如博文上半部分中介绍的，追加文件（Append Only File）是一种更好的保持数据一致性的方式。
    611. #即使当服务器断电时，也仅会有1秒钟的写请求丢失，当redis进程出现问题且操作系统运行正常时，
    612. #甚至只会丢失一条写请求。
    613. #
    614. # The Append Only File is an alternative persistence mode that provides
    615. # much better durability. For instance using the default data fsync policy
    616. # (see later in the config file) Redis can lose just one second of writes in a
    617. # dramatic event like a server power outage, or a single write if something
    618. # wrong with the Redis process itself happens, but the operating system is
    619. # still running correctly.
    620. #
    621. # AOF and RDB persistence can be enabled at the same time without problems.
    622. # If the AOF is enabled on startup Redis will load the AOF, that is the file
    623. # with the better durability guarantees.
    624. #我们建议大家，AOF机制和RDB机制可以同时使用，不会有任何冲突
    625. # Please check http://redis.io/topics/persistence for more information.
    627. appendonly no
    629. # The name of the append only file (default: "appendonly.aof")
    630. #我们还可以设置aof文件的名称：
    631. appendfilename "appendonly.aof"
    633. # The fsync() call tells the Operating System to actually write data on disk
    634. # instead of waiting for more data in the output buffer. Some OS will really flush
    635. # data on disk, some other OS will just try to do it ASAP.
    636. #fsync()调用，用来告诉操作系统立即将缓存的指令写入磁盘。一些操作系统会“立即”进行，
    637. #而另外一些操作系统则会“尽快”进行。
    638. # Redis supports three different modes:
    639. #
    640. # no: don't fsync, just let the OS flush the data when it wants. Faster.
    641. # always: fsync after every write to the append only log . Slow, Safest.
    642. # everysec: fsync only one time every second. Compromise.
    643. #
    644. # The default is "everysec", as that's usually the right compromise between
    645. # speed and data safety. It's up to you to understand if you can relax this to
    646. # "no" that will let the operating system flush the output buffer when
    647. # it wants, for better performances (but if you can live with the idea of
    648. # some data loss consider the default persistence mode that's snapshotting),
    649. # or on the contrary, use "always" that's very slow but a bit safer than
    650. # everysec.
    651. #
    652. # More details please check the following article:
    653. # http://antirez.com/post/redis-persistence-demystified.html
    654. #
    655. # If unsure, use "everysec".
    656. #redis支持三种不同的模式：
    657. #1.no：不调用fsync()。而是让操作系统自行决定sync的时间。这种模式下，redis的性能会最快。
    658. #2.always：在每次写请求后都调用fsync()。这种模式下，redis会相对较慢，但数据最安全。
    659. #3.everysec：每秒钟调用一次fsync()。这是性能和安全的折衷。
    661. # appendfsync always
    662. #默认情况下为everysec
    663. appendfsync everysec
    664. # appendfsync no
    666. # When the AOF fsync policy is set to always or everysec, and a background
    667. # saving process (a background save or AOF log background rewriting) is
    668. # performing a lot of I/O against the disk, in some Linux configurations
    669. # Redis may block too long on the fsync() call. Note that there is no fix for
    670. # this currently, as even performing fsync in a different thread will block
    671. # our synchronous write(2) call.
    672. #当fsync方式设置为always或everysec时，如果后台持久化进程需要执行一个很大的磁盘IO操作，
    673. #那么redis可能会在fsync()调用时卡住。目前尚未修复这个问题，
    674. #这是因为即使我们在另一个新的线程中去执行fsync()，也会阻塞住同步写调用
    675. # In order to mitigate this problem it's possible to use the following option
    676. # that will prevent fsync() from being called in the main process while a
    677. # BGSAVE or BGREWRITEAOF is in progress.
    678. #
    679. # This means that while another child is saving, the durability of Redis is
    680. # the same as "appendfsync none". In practical terms, this means that it is
    681. # possible to lose up to 30 seconds of log in the worst scenario (with the
    682. # default Linux settings).
    683. # 
    684. # If you have latency problems turn this to "yes". Otherwise leave it as
    685. # "no" that is the safest pick from the point of view of durability.
    686. #为了缓解这个问题，我们可以使用下面的配置项，这样的话，当BGSAVE或BGWRITEAOF运行时，
    687. #fsync()在主进程中的调用会被阻止。这意味着当另一路进程正在对AOF文件进行重构时，
    688. #redis的持久化功能就失效了，就好像我们设置了“appendsync none”一样。
    689. #如果你的redis有时延问题，那么请将下面的选项设置为yes。
    690. #否则请保持no，因为这是保证数据完整性的最安全的选择。
    691. no-appendfsync-on-rewrite no
    693. # Automatic rewrite of the append only file.
    694. # Redis is able to automatically rewrite the log file implicitly calling
    695. # BGREWRITEAOF when the AOF log size grows by the specified percentage.
    696. # 我们允许redis自动重写aof。当aof增长到一定规模时，
    697. #redis会隐式调用BGREWRITEAOF来重写log文件，以缩减文件体积。
    698. # This is how it works: Redis remembers the size of the AOF file after the
    699. # latest rewrite (if no rewrite has happened since the restart, the size of
    700. # the AOF at startup is used).
    701. #
    702. # This base size is compared to the current size. If the current size is
    703. # bigger than the specified percentage, the rewrite is triggered. Also
    704. # you need to specify a minimal size for the AOF file to be rewritten, this
    705. # is useful to avoid rewriting the AOF file even if the percentage increase
    706. # is reached but it is still pretty small.
    707. #
    708. # Specify a percentage of zero in order to disable the automatic AOF
    709. # rewrite feature.
    711. #redis是这样工作的：redis会记录上次重写时的aof大小。假如redis自启动至今
    712. #还没有进行过重写，那么启动时aof文件的大小会被作为基准值。
    713. #这个基准值会和当前的aof大小进行比较。如果当前aof大小超出所设置的增长比例，
    714. #则会触发重写。另外，你还需要设置一个最小大小，是为了防止在aof很小时就触发重写
    715. #如果设置auto-aof-rewrite-percentage为0，则会关闭此重写功能
    716. auto-aof-rewrite-percentage 100
    717. auto-aof-rewrite-min-size 64mb
    719. # An AOF file may be found to be truncated at the end during the Redis
    720. # startup process, when the AOF data gets loaded back into memory.
    721. # This may happen when the system where Redis is running
    722. # crashes, especially when an ext4 filesystem is mounted without the
    723. # data=ordered option (however this can't happen when Redis itself
    724. # crashes or aborts but the operating system still works correctly).
    725. #
    726. # Redis can either exit with an error when this happens, or load as much
    727. # data as possible (the default now) and start if the AOF file is found
    728. # to be truncated at the end. The following option controls this behavior.
    729. #
    730. # If aof-load-truncated is set to yes, a truncated AOF file is loaded and
    731. # the Redis server starts emitting a log to inform the user of the event.
    732. # Otherwise if the option is set to no, the server aborts with an error
    733. # and refuses to start. When the option is set to no, the user requires
    734. # to fix the AOF file using the "redis-check-aof" utility before to restart
    735. # the server.
    736. #
    737. # Note that if the AOF file will be found to be corrupted in the middle
    738. # the server will still exit with an error. This option only applies when
    739. # Redis will try to read more data from the AOF file but not enough bytes
    740. # will be found.
    741. aof-load-truncated yes
    743. ################################ LUA SCRIPTING  ###############################
    745. # Max execution time of a Lua script in milliseconds.
    746. #
    747. # If the maximum execution time is reached Redis will log that a script is
    748. # still in execution after the maximum allowed time and will start to
    749. # reply to queries with an error.
    750. #
    751. # When a long running script exceeds the maximum execution time only the
    752. # SCRIPT KILL and SHUTDOWN NOSAVE commands are available. The first can be
    753. # used to stop a script that did not yet called write commands. The second
    754. # is the only way to shut down the server in the case a write command was
    755. # already issued by the script but the user doesn't want to wait for the natural
    756. # termination of the script.
    757. #
    758. # Set it to 0 or a negative value for unlimited execution without warnings.
    759. #lua脚本的最大运行时间是需要被严格限制的，要注意单位是毫秒
    760. #如果此值设置为0或负数，则既不会有报错也不会有时间限制
    761. lua-time-limit 5000
    763. ################################ REDIS CLUSTER  ###############################
    764. #
    765. # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    766. # WARNING EXPERIMENTAL: Redis Cluster is considered to be stable code, however
    767. # in order to mark it as "mature" we need to wait for a non trivial percentage
    768. # of users to deploy it in production.
    769. # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    770. #
    771. # Normal Redis instances can't be part of a Redis Cluster; only nodes that are
    772. # started as cluster nodes can. In order to start a Redis instance as a
    773. # cluster node enable the cluster support uncommenting the following:
    774. #
    775. # cluster-enabled yes
    777. # Every cluster node has a cluster configuration file. This file is not
    778. # intended to be edited by hand. It is created and updated by Redis nodes.
    779. # Every Redis Cluster node requires a different cluster configuration file.
    780. # Make sure that instances running in the same system do not have
    781. # overlapping cluster configuration file names.
    782. #
    783. # cluster-config-file nodes-6379.conf
    785. # Cluster node timeout is the amount of milliseconds a node must be unreachable
    786. # for it to be considered in failure state.
    787. # Most other internal time limits are multiple of the node timeout.
    788. #
    789. # cluster-node-timeout 15000
    791. # A slave of a failing master will avoid to start a failover if its data
    792. # looks too old.
    793. #
    794. # There is no simple way for a slave to actually have a exact measure of
    795. # its "data age", so the following two checks are performed:
    796. #
    797. # 1) If there are multiple slaves able to failover, they exchange messages
    798. #    in order to try to give an advantage to the slave with the best
    799. #    replication offset (more data from the master processed).
    800. #    Slaves will try to get their rank by offset, and apply to the start
    801. #    of the failover a delay proportional to their rank.
    802. #
    803. # 2) Every single slave computes the time of the last interaction with
    804. #    its master. This can be the last ping or command received (if the master
    805. #    is still in the "connected" state), or the time that elapsed since the
    806. #    disconnection with the master (if the replication link is currently down).
    807. #    If the last interaction is too old, the slave will not try to failover
    808. #    at all.
    809. #
    810. # The point "2" can be tuned by user. Specifically a slave will not perform
    811. # the failover if, since the last interaction with the master, the time
    812. # elapsed is greater than:
    813. #
    814. #   (node-timeout * slave-validity-factor) + repl-ping-slave-period
    815. #
    816. # So for example if node-timeout is 30 seconds, and the slave-validity-factor
    817. # is 10, and assuming a default repl-ping-slave-period of 10 seconds, the
    818. # slave will not try to failover if it was not able to talk with the master
    819. # for longer than 310 seconds.
    820. #
    821. # A large slave-validity-factor may allow slaves with too old data to failover
    822. # a master, while a too small value may prevent the cluster from being able to
    823. # elect a slave at all.
    824. #
    825. # For maximum availability, it is possible to set the slave-validity-factor
    826. # to a value of 0, which means, that slaves will always try to failover the
    827. # master regardless of the last time they interacted with the master.
    828. # (However they'll always try to apply a delay proportional to their
    829. # offset rank).
    830. #
    831. # Zero is the only value able to guarantee that when all the partitions heal
    832. # the cluster will always be able to continue.
    833. #
    834. # cluster-slave-validity-factor 10
    836. # Cluster slaves are able to migrate to orphaned masters, that are masters
    837. # that are left without working slaves. This improves the cluster ability
    838. # to resist to failures as otherwise an orphaned master can't be failed over
    839. # in case of failure if it has no working slaves.
    840. #
    841. # Slaves migrate to orphaned masters only if there are still at least a
    842. # given number of other working slaves for their old master. This number
    843. # is the "migration barrier". A migration barrier of 1 means that a slave
    844. # will migrate only if there is at least 1 other working slave for its master
    845. # and so forth. It usually reflects the number of slaves you want for every
    846. # master in your cluster.
    847. #
    848. # Default is 1 (slaves migrate only if their masters remain with at least
    849. # one slave). To disable migration just set it to a very large value.
    850. # A value of 0 can be set but is useful only for debugging and dangerous
    851. # in production.
    852. #
    853. # cluster-migration-barrier 1
    855. # By default Redis Cluster nodes stop accepting queries if they detect there
    856. # is at least an hash slot uncovered (no available node is serving it).
    857. # This way if the cluster is partially down (for example a range of hash slots
    858. # are no longer covered) all the cluster becomes, eventually, unavailable.
    859. # It automatically returns available as soon as all the slots are covered again.
    860. #
    861. # However sometimes you want the subset of the cluster which is working,
    862. # to continue to accept queries for the part of the key space that is still
    863. # covered. In order to do so, just set the cluster-require-full-coverage
    864. # option to no.
    865. #
    866. # cluster-require-full-coverage yes
    868. # In order to setup your cluster make sure to read the documentation
    869. # available at http://redis.io web site.
    871. ################################## SLOW LOG ###################################
    873. # The Redis Slow Log is a system to log queries that exceeded a specified
    874. # execution time. The execution time does not include the I/O operations
    875. # like talking with the client, sending the reply and so forth,
    876. # but just the time needed to actually execute the command (this is the only
    877. # stage of command execution where the thread is blocked and can not serve
    878. # other requests in the meantime).
    879. # 
    880. # You can configure the slow log with two parameters: one tells Redis
    881. # what is the execution time, in microseconds, to exceed in order for the
    882. # command to get logged, and the other parameter is the length of the
    883. # slow log. When a new command is logged the oldest one is removed from the
    884. # queue of logged commands.
    886. # The following time is expressed in microseconds, so 1000000 is equivalent
    887. # to one second. Note that a negative number disables the slow log, while
    888. # a value of zero forces the logging of every command.
    890. #redis慢日志是指一个系统进行日志查询超过了指定的时长。这个时长不包括IO操作，
    891. #比如与客户端的交互、发送响应内容等，而仅包括实际执行查询命令的时间。
    892. #针对慢日志，你可以设置两个参数，一个是执行时长，单位是微秒，另一个是慢日志的长度。
    893. #当一个新的命令被写入日志时，最老的一条会从命令日志队列中被移除。
    895. #单位是微秒，即1000000表示一秒。负数则会禁用慢日志功能，而0则表示强制记录每一个命令。
    896. slowlog-log-slower-than 10000
    898. # There is no limit to this length. Just be aware that it will consume memory.
    899. # You can reclaim memory used by the slow log with SLOWLOG RESET.
    900. #慢日志最大长度，可以随便填写数值，没有上限，但要注意它会消耗内存。你可以使用SLOWLOG RESET来重设这个值。
    901. slowlog-max-len 128
    903. ################################ LATENCY MONITOR ##############################
    905. # The Redis latency monitoring subsystem samples different operations
    906. # at runtime in order to collect data related to possible sources of
    907. # latency of a Redis instance.
    908. #
    909. # Via the LATENCY command this information is available to the user that can
    910. # print graphs and obtain reports.
    911. #
    912. # The system only logs operations that were performed in a time equal or
    913. # greater than the amount of milliseconds specified via the
    914. # latency-monitor-threshold configuration directive. When its value is set
    915. # to zero, the latency monitor is turned off.
    916. #
    917. # By default latency monitoring is disabled since it is mostly not needed
    918. # if you don't have latency issues, and collecting data has a performance
    919. # impact, that while very small, can be measured under big load. Latency
    920. # monitoring can easily be enabled at runtime using the command
    921. # "CONFIG SET latency-monitor-threshold <milliseconds>" if needed.
    922. latency-monitor-threshold 0
    924. ############################# Event notification ##############################
    926. # Redis can notify Pub/Sub clients about events happening in the key space.
    927. # This feature is documented at http://redis.io/topics/notifications
    928. #
    929. # For instance if keyspace events notification is enabled, and a client
    930. # performs a DEL operation on key "foo" stored in the Database 0, two
    931. # messages will be published via Pub/Sub:
    932. #
    933. # PUBLISH __keyspace@0__:foo del
    934. # PUBLISH __keyevent@0__:del foo
    935. #
    936. # It is possible to select the events that Redis will notify among a set
    937. # of classes. Every class is identified by a single character:
    938. #
    939. #  K     Keyspace events, published with __keyspace@<db>__ prefix.
    940. #  E     Keyevent events, published with __keyevent@<db>__ prefix.
    941. #  g     Generic commands (non-type specific) like DEL, EXPIRE, RENAME, ...
    942. #  $     String commands
    943. #  l     List commands
    944. #  s     Set commands
    945. #  h     Hash commands
    946. #  z     Sorted set commands
    947. #  x     Expired events (events generated every time a key expires)
    948. #  e     Evicted events (events generated when a key is evicted for maxmemory)
    949. #  A     Alias for g$lshzxe, so that the "AKE" string means all the events.
    950. #
    951. #  The "notify-keyspace-events" takes as argument a string that is composed
    952. #  of zero or multiple characters. The empty string means that notifications
    953. #  are disabled.
    954. #
    955. #  Example: to enable list and generic events, from the point of view of the
    956. #           event name, use:
    957. #
    958. #  notify-keyspace-events Elg
    959. #
    960. #  Example 2: to get the stream of the expired keys subscribing to channel
    961. #             name __keyevent@0__:expired use:
    962. #
    963. #  notify-keyspace-events Ex
    964. #
    965. #  By default all notifications are disabled because most users don't need
    966. #  this feature and the feature has some overhead. Note that if you don't
    967. #  specify at least one of K or E, no events will be delivered.
    968. notify-keyspace-events ""
    970. ############################### ADVANCED CONFIG ###############################
    972. # Hashes are encoded using a memory efficient data structure when they have a
    973. # small number of entries, and the biggest entry does not exceed a given
    974. # threshold. These thresholds can be configured using the following directives.
    975. #有关哈希数据结构的一些配置项
    976. hash-max-ziplist-entries 512
    977. hash-max-ziplist-value 64
    979. # Similarly to hashes, small lists are also encoded in a special way in order
    980. # to save a lot of space. The special representation is only used when
    981. # you are under the following limits:
    982. #有关列表数据结构的一些配置项
    983. list-max-ziplist-entries 512
    984. list-max-ziplist-value 64
    986. # Sets have a special encoding in just one case: when a set is composed
    987. # of just strings that happen to be integers in radix 10 in the range
    988. # of 64 bit signed integers.
    989. # The following configuration setting sets the limit in the size of the
    990. # set in order to use this special memory saving encoding.
    991. #有关集合数据结构的配置项
    992. set-max-intset-entries 512
    994. # Similarly to hashes and lists, sorted sets are also specially encoded in
    995. # order to save a lot of space. This encoding is only used when the length and
    996. # elements of a sorted set are below the following limits:
    997. #有关有序集合数据结构的配置项
    998. zset-max-ziplist-entries 128
    999. zset-max-ziplist-value 64
    1001. # HyperLogLog sparse representation bytes limit. The limit includes the
    1002. # 16 bytes header. When an HyperLogLog using the sparse representation crosses
    1003. # this limit, it is converted into the dense representation.
    1004. #
    1005. # A value greater than 16000 is totally useless, since at that point the
    1006. # dense representation is more memory efficient.
    1007. #
    1008. # The suggested value is ~ 3000 in order to have the benefits of
    1009. # the space efficient encoding without slowing down too much PFADD,
    1010. # which is O(N) with the sparse encoding. The value can be raised to
    1011. # ~ 10000 when CPU is not a concern, but space is, and the data set is
    1012. # composed of many HyperLogLogs with cardinality in the 0 - 15000 range.
    1013. hll-sparse-max-bytes 3000
    1015. # Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in
    1016. # order to help rehashing the main Redis hash table (the one mapping top-level
    1017. # keys to values). The hash table implementation Redis uses (see dict.c)
    1018. # performs a lazy rehashing: the more operation you run into a hash table
    1019. # that is rehashing, the more rehashing "steps" are performed, so if the
    1020. # server is idle the rehashing is never complete and some more memory is used
    1021. # by the hash table.
    1022. # 
    1023. # The default is to use this millisecond 10 times every second in order to
    1024. # actively rehash the main dictionaries, freeing memory when possible.
    1025. #
    1026. # If unsure:
    1027. # use "activerehashing no" if you have hard latency requirements and it is
    1028. # not a good thing in your environment that Redis can reply from time to time
    1029. # to queries with 2 milliseconds delay.
    1030. #
    1031. # use "activerehashing yes" if you don't have such hard requirements but
    1032. # want to free memory asap when possible.
    1033. #关于是否需要再哈希的配置项
    1034. activerehashing yes
    1036. # The client output buffer limits can be used to force disconnection of clients
    1037. # that are not reading data from the server fast enough for some reason (a
    1038. # common reason is that a Pub/Sub client can't consume messages as fast as the
    1039. # publisher can produce them).
    1040. #
    1041. # The limit can be set differently for the three different classes of clients:
    1042. #
    1043. # normal -> normal clients including MONITOR clients
    1044. # slave  -> slave clients
    1045. # pubsub -> clients subscribed to at least one pubsub channel or pattern
    1046. #
    1047. # The syntax of every client-output-buffer-limit directive is the following:
    1048. #
    1049. # client-output-buffer-limit <class> <hard limit> <soft limit> <soft seconds>
    1050. #
    1051. # A client is immediately disconnected once the hard limit is reached, or if
    1052. # the soft limit is reached and remains reached for the specified number of
    1053. # seconds (continuously).
    1054. # So for instance if the hard limit is 32 megabytes and the soft limit is
    1055. # 16 megabytes / 10 seconds, the client will get disconnected immediately
    1056. # if the size of the output buffers reach 32 megabytes, but will also get
    1057. # disconnected if the client reaches 16 megabytes and continuously overcomes
    1058. # the limit for 10 seconds.
    1059. #
    1060. # By default normal clients are not limited because they don't receive data
    1061. # without asking (in a push way), but just after a request, so only
    1062. # asynchronous clients may create a scenario where data is requested faster
    1063. # than it can read.
    1064. #
    1065. # Instead there is a default limit for pubsub and slave clients, since
    1066. # subscribers and slaves receive data in a push fashion.
    1067. #
    1068. # Both the hard or the soft limit can be disabled by setting them to zero.
    1069. #关于客户端输出缓冲的控制项
    1070. client-output-buffer-limit normal 0 0 0
    1071. client-output-buffer-limit slave 256mb 64mb 60
    1072. client-output-buffer-limit pubsub 32mb 8mb 60
    1074. # Redis calls an internal function to perform many background tasks, like
    1075. # closing connections of clients in timeot, purging expired keys that are
    1076. # never requested, and so forth.
    1077. #
    1078. # Not all tasks are perforemd with the same frequency, but Redis checks for
    1079. # tasks to perform according to the specified "hz" value.
    1080. #
    1081. # By default "hz" is set to 10. Raising the value will use more CPU when
    1082. # Redis is idle, but at the same time will make Redis more responsive when
    1083. # there are many keys expiring at the same time, and timeouts may be
    1084. # handled with more precision.
    1085. #
    1086. # The range is between 1 and 500, however a value over 100 is usually not
    1087. # a good idea. Most users should use the default of 10 and raise this up to
    1088. # 100 only in environments where very low latency is required.
    1089. #有关频率的配置项
    1090. hz 10
    1092. # When a child rewrites the AOF file, if the following option is enabled
    1093. # the file will be fsync-ed every 32 MB of data generated. This is useful
    1094. # in order to commit the file to the disk more incrementally and avoid
    1095. # big latency spikes.
    1096. #有关重写aof的配置项
    1097. aof-rewrite-incremental-fsync yes
    1099. ################################## INCLUDES ###################################
    1101. # Include one or more other config files here.  This is useful if you
    1102. # have a standard template that goes to all Redis server but also need
    1103. # to customize a few per-server settings.  Include files can include
    1104. # other files, so use this wisely.
    1105. #
    1106. # include /path/to/local.conf
    1107. # include /path/to/other.conf