记录下来的日志，我想看ClientPreparedStatement的第 953 行到底发生了什么，结果在下载的源文件里死活找不到对应的入口：

    1. Caused by: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Lock wait timeout exceeded; try restarting transaction
    2.     at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:123)
    3.     at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
    4.     at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
    5.     at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953)
    6.     at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1092)
    7.     at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1040)
    8.     at com.mysql.cj.jdbc.ClientPreparedStatement.executeLargeUpdate(ClientPreparedStatement.java:1347)
    9.     at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdate(ClientPreparedStatement.java:1025)
    10.     at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeUpdate(ProxyPreparedStatement.java:61)
    11.     at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeUpdate(HikariProxyPreparedStatement.java)
    12.     at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:197)
    13.     ... 186 common frames omitted

    我查找ClientPreparedStatement的第 953 行：

    1.     protected <M extends Message> ResultSetInternalMethods executeInternal(int maxRowsToRetrieve, M sendPacket, boolean createStreamingResultSet,
    2.             boolean queryIsSelectOnly, ColumnDefinition metadata, boolean isBatch) throws SQLException {
    3.         synchronized (checkClosed().getConnectionMutex()) {
    4.             try {
    6.                 JdbcConnection locallyScopedConnection = this.connection;
    8.                 ((PreparedQuery<?>) this.query).getQueryBindings()
    9.                         .setNumberOfExecutions(((PreparedQuery<?>) this.query).getQueryBindings().getNumberOfExecutions() + 1);
    11.                 ResultSetInternalMethods rs;
    13.                 CancelQueryTask timeoutTask = null;
    15.                 try {
    16.                     timeoutTask = startQueryTimer(this, getTimeoutInMillis());
    18.                     if (!isBatch) {
    19.                         statementBegins();
    20.                     }
    22.                     rs = ((NativeSession) locallyScopedConnection.getSession()).execSQL(this, null, maxRowsToRetrieve, (NativePacketPayload) sendPacket,
    23.                             createStreamingResultSet, getResultSetFactory(), metadata, isBatch);
    25.                     if (timeoutTask != null) {
    26.                         stopQueryTimer(timeoutTask, true, true);
    27.                         timeoutTask = null;
    28.                     }
    30.                 } finally {
    31.                     if (!isBatch) {
    32.                         this.query.getStatementExecuting().set(false);
    33.                     }
    35.                     stopQueryTimer(timeoutTask, false, false);
    36.                 }
    38.                 return rs;
    39.             } catch (NullPointerException npe) {
    40.                 checkClosed(); // we can't synchronize ourselves against async connection-close due to deadlock issues, so this is the next best thing for
    41.                               // this particular corner case.
    43.                 throw npe;
    44.             }
    45.         }
    46.     }        // 这一行在文件中是第953行

    人傻了，通过字节码发现确实是存在的对应的一段操作方法的，那我就纳闷了，后来突然想起来代码增强这一件事，去 Github 上还真找到了，这一部分就是用来增强一些方法的异常捕获能力。当build源码时会触发增强，详情看 build.xml