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mysql - 与 Amazon RDS MySQL & Play Framework 1.2.5(c3p0 默认设置)的连接偶尔挂起

转载 作者：可可西里 更新时间：2023-11-01 07:35:29 25 4
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我们在使用 Amazon-hosted Play application with RDS Mysql 时遇到问题.

有时应用程序会停止响应。今天我用 jstack -F 检查线程状态，有多个线程卡在 c3p0 连接的 native 代码中:

Thread 14060: (state = IN_NATIVE)
 - java.net.SocketInputStream.socketRead0(java.io.FileDescriptor, byte[], int, int, int) @bci=0 (Compiled frame; information may be imprecise)
 - java.net.SocketInputStream.read(byte[], int, int, int) @bci=79, line=150 (Compiled frame)
 - java.net.SocketInputStream.read(byte[], int, int) @bci=11, line=121 (Compiled frame)
 - com.mysql.jdbc.util.ReadAheadInputStream.fill(int) @bci=262, line=114 (Compiled frame)
 - com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(byte[], int, int) @bci=176, line=161 (Compiled frame)
 - com.mysql.jdbc.util.ReadAheadInputStream.read(byte[], int, int) @bci=48, line=189 (Compiled frame)
 - com.mysql.jdbc.MysqlIO.readFully(java.io.InputStream, byte[], int, int) @bci=34, line=3036 (Compiled frame)
 - com.mysql.jdbc.MysqlIO.reuseAndReadPacket(com.mysql.jdbc.Buffer, int) @bci=23, line=3489 (Compiled frame)
 - com.mysql.jdbc.MysqlIO.reuseAndReadPacket(com.mysql.jdbc.Buffer) @bci=3, line=3478 (Compiled frame)
 - com.mysql.jdbc.MysqlIO.checkErrorPacket(int) @bci=12, line=4019 (Compiled frame)
 - com.mysql.jdbc.MysqlIO.sendCommand(int, java.lang.String, com.mysql.jdbc.Buffer, boolean, java.lang.String, int) @bci=428, line=2490 (Compiled frame)
 - com.mysql.jdbc.MysqlIO.sqlQueryDirect(com.mysql.jdbc.StatementImpl, java.lang.String, java.lang.String, com.mysql.jdbc.Buffer, int, int, int, boolean, java.lang.String, com.mysql.jdbc.Field[]) @bci=559, line=2651 (Compiled frame)
 - com.mysql.jdbc.ConnectionImpl.execSQL(com.mysql.jdbc.StatementImpl, java.lang.String, int, com.mysql.jdbc.Buffer, int, int, boolean, java.lang.String, com.mysql.jdbc.Field[], boolean) @bci=130, line=2677 (Compiled frame)
 - com.mysql.jdbc.ConnectionImpl.execSQL(com.mysql.jdbc.StatementImpl, java.lang.String, int, com.mysql.jdbc.Buffer, int, int, boolean, java.lang.String, com.mysql.jdbc.Field[]) @bci=17, line=2627 (Compiled frame)
 - com.mysql.jdbc.StatementImpl.executeQuery(java.lang.String) @bci=534, line=1556 (Compiled frame)
 - com.mysql.jdbc.DatabaseMetaData$9.forEach(java.lang.Object) @bci=174, line=5013 (Compiled frame)
 - com.mysql.jdbc.IterateBlock.doForAll() @bci=25, line=51 (Compiled frame)
 - com.mysql.jdbc.DatabaseMetaData.getTables(java.lang.String, java.lang.String, java.lang.String, java.lang.String[]) @bci=280, line=4991 (Compiled frame)
 - com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnectionNoQuery(java.sql.Connection, java.lang.Throwable[]) @bci=21, line=185 (Compiled frame)
 - com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(java.sql.Connection, java.lang.String, java.lang.Throwable[]) @bci=7, line=62 (Compiled frame)
 - com.mchange.v2.c3p0.AbstractConnectionTester.activeCheckConnection(java.sql.Connection) @bci=4, line=67 (Compiled frame)
 - com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(java.lang.Object) @bci=122, line=368 (Compiled frame)
 - com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(java.lang.Object) @bci=26, line=310 (Compiled frame)
 - com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run() @bci=35, line=1999 (Interpreted frame)
 - com.mchange.v2.async.ThreadPerTaskAsynchronousRunner$TaskThread.run() @bci=41, line=255 (Interpreted frame)

如果没有设置其他连接测试，DefaultConnectionTester.activeCheckConnectionNoQuery 似乎会检查 DatabaseMetaData.getTables。

C3p0 手册有关于 configuring proper connection testing 的说明和 this answer有关于 Play 的 c3p0 设置说明!但我想知道:

  • 有什么方法可以检查这背后的问题是什么？
    • 我之前遇到的标准“Mysql 连接在 8 小时后被终止”结果是异常
  • 既然已经完成，似乎有一些与 c3p0/Play/Hibernate 的默认连接测试？
    • 我有一种预感，默认情况下 c3p0 不进行连接测试
      • 默认值 idleConnectionTestPeriod = 0，testConnectionOnCheckin = false，testConnectionOnCheckout = false
  • 有没有办法为连接测试查询设置超时？
    • 例如，即使我配置了一些合理的 preferredTestQuery，该查询是否也有在当前 getTables() 调用时挂起的风险？
  • 还有什么我应该考虑的吗？

使用 automaticTestTable 更新(不是解决方案)

我们将 c3p0.automaticTestTable 设置为进行更合理的连接测试，但这似乎并没有解决问题，只是稍微更改了线程的堆栈跟踪。

在类似的情况下，我们现在有如下线程堆栈:

"Task-Thread-for-com.mchange.v2.async.ThreadPerTaskAsynchronousRunner@6064cd08" daemon prio=10 tid=0x00007f53d403a000 nid=0x63dd runnable [0x00007f53dce4a000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:150)
        at java.net.SocketInputStream.read(SocketInputStream.java:121)
        at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:114)
        at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:161)
        at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:189)
        - locked <0x00000000dbecd0d8> (a com.mysql.jdbc.util.ReadAheadInputStream)
        at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:3036)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3489)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3478)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4019)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2490)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2651)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2677)
        - locked <0x00000000dbec1a70> (a com.mysql.jdbc.JDBC4Connection)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2627)
        at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1556)
        - locked <0x00000000dbec1a70> (a com.mysql.jdbc.JDBC4Connection)
        - locked <0x00000000d1330078> (a com.mysql.jdbc.StatementImpl)
        at com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(DefaultConnectionTester.java:73)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:374)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(C3P0PooledConnectionPool.java:310)
        at com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run(BasicResourcePool.java:1999)
        at com.mchange.v2.async.ThreadPerTaskAsynchronousRunner$TaskThread.run(ThreadPerTaskAsynchronousRunner.java:255)

播放线程正在等待获得数据库连接:

"play-thread-3" prio=10 tid=0x00007f53c400b000 nid=0x5b3e in Object.wait() [0x00007f53ddd57000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000db9f38f8> (a com.mchange.v2.resourcepool.BasicResourcePool)
        at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:579)
        - locked <0x00000000db9f38f8> (a com.mchange.v2.resourcepool.BasicResourcePool)
        at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:584)
        ... (näitä vaihtelevat määrät)
        at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:584)
        - locked <0x00000000db9f38f8> (a com.mchange.v2.resourcepool.BasicResourcePool)
        at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:584)
        - locked <0x00000000db9f38f8> (a com.mchange.v2.resourcepool.BasicResourcePool)
        at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
        at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
        at org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider.getConnection(InjectedDataSourceConnectionProvider.java:71)
        at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
        at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
        at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:160)
        at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:81)
        at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1473)
        at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:60)
        at play.db.jpa.JPAPlugin.startTx(JPAPlugin.java:377)
        at play.db.jpa.JPAPlugin.beforeInvocation(JPAPlugin.java:345)
        at play.plugins.PluginCollection.beforeInvocation(PluginCollection.java:473)
        at play.Invoker$Invocation.before(Invoker.java:217)
        at play.Invoker$Invocation.run(Invoker.java:277)
        at play.server.PlayHandler$NettyInvocation.run(PlayHandler.java:229)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
        at java.util.concurrent.FutureTask.run(FutureTask.java:166)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
        at java.lang.Thread.run(Thread.java:722)

一些注意事项:

  • 有可能(至少在理论上)许多连接恰好在读取堆栈转储的同时被测试，尽管我认为这不太可能。
  • 在another question有人提到数据死锁或硬件/网络问题可能会导致这种行为。
    • 至少不应该有任何正在进行的模式修改。

br，桃子

对自己的回答:

  • 没有找到连接挂起的原因:(
    • RDS 有 MySQL 的 error.log，不幸的是什么都没有
  • Play 对 c3p0 ComboPooledDataSource 有一些默认设置(在 DBPlugin.onApplicationStart() 中)
    • idleTimeExcessConnections :来自 application.conf db.pool.maxIdleTimeExcessConnections(默认为 0)
    • checkoutTimeout:来自 application.conf db.pool.timeout(默认 5000)
    • 空闲连接测试周期:10
    • setTestConnectionOnCheckin : true
    • 另外，conf/c3p0.properties可以用来设置自定义属性
  • 还没有找到为连接测试设置超时的方法(通过简短的 DefaultConnectionTester 源代码查找可能不支持)

我们继续设置c3p0.automaticTestTable，稍后看看会不会有问题。

更新:不幸的是，我们还没有解决问题 :( 此外，对于 automaticTestTable，连接测试似乎卡住了 java.net.SocketInputStream.socketRead0(Native Method)

再次回答自己:

我们最终使用 c3p0:s maxAdministrativeTaskTime 尝试这种“为连接测试查询设置超时”的方法.这有点像 hack，所以要看看这是否是最终解决方案(如果可行的话)。

到目前为止还没有问题，我们将看看它是如何工作的。日志中也没有 c3p0 错误/堆栈跟踪，我希望这个中断显示在日志中吗？尚未发生超时，或者我们应该调整日志记录配置以显示 c3p0 日志。

更新(2013 年 4 月 4 日):此后问题(可能)不再经常发生，但时不时发生 :(

最佳答案

再次回答自己:

我们首先使用了为 MySQL 驱动程序指定的 socketTimeout，这样连接测试就不会卡住。

似乎底层的 TCP 连接结束了，因此没有来自服务器的应答(TCP ACK 或任何东西)。

更新:最终的解决方案是为 AWS 支持提供 tcpdump，他们在 AWS 基础设施中发现了一些案例。他们建议我们在 EC2 实例的安全组中打开临时端口范围。更多讨论 AWS forum .

关于mysql - 与 Amazon RDS MySQL & Play Framework 1.2.5(c3p0 默认设置)的连接偶尔挂起，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15249411/

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