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  1. IronJacamar
  2. JBJCA-1276

Prefill race condition in flush

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Details

    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Done
    • 1.0.31.Final, 1.1.9.Final
    • 1.0.33.Final
    • None
    • None

    Description

      There is a race condition between AbstractPool and SemaphoreArrayListManagedConnectionPool.

      https://github.com/ironjacamar/ironjacamar/blob/ironjacamar-1.0.31.Final/core/src/main/java/org/jboss/jca/core/connectionmanager/pool/AbstractPool.java#L354
      https://github.com/ironjacamar/ironjacamar/blob/ironjacamar-1.0.31.Final/core/src/main/java/org/jboss/jca/core/connectionmanager/pool/mcp/SemaphoreArrayListManagedConnectionPool.java#L625

      AbstractPool flushes the mcp, mcp invokes PoolFiller which works in a separate thread. However AbstractPool is going to unregister the empty mcp and this mcp is no longer used. Then the dead mcp is prefilled in a separate thread by PoolFiller.

      At next getConnection(), the mcp is re-initialized and prefilled.

      I've attached logs, prefill enabled and min-size is 10. Boot server, invoke flush-all-connection-in-pool, getConnection() then killed. The prefill is done 3 times where it should be twice.

      16:26:04,254 DEBUG [org.jboss.jca.core.connectionmanager.pool.strategy.OnePool] (management-handler-thread - 1) ExampleDS: flush(true)
      16:26:04,255 TRACE [org.jboss.jca.core.connectionmanager.pool.strategy.OnePool] (management-handler-thread - 1) Destroying flushed connection org.jboss.jca.core.connectionmanager.listener.TxConnectionListener@1d298ed8[state=NORMAL managed connection=org.jboss.jca.adapters.jdbc.local.LocalManagedConnection@4ae26a1b connection handles=0 lastUse=1434353148384 trackByTx=false pool=org.jboss.jca.core.connectionmanager.pool.strategy.OnePool@56a43905 pool internal context=SemaphoreArrayListManagedConnectionPool@5cbd770e[pool=ExampleDS] xaResource=LocalXAResourceImpl@379ba3b3[connectionListener=1d298ed8 connectionManager=4b18594a warned=false currentXid=null productName=H2 productVersion=@PROJECT_VERSION@ (2012-07-13) jndiName=java:jboss/datasources/ExampleDS] txSync=null]
      (repeat 10 times)
      16:02:20,666 TRACE [org.jboss.jca.core.connectionmanager.pool.strategy.OnePool] (management-handler-thread - 7) Shutdown - Pool: ExampleDS MCP: 2f5a2102
      16:02:20,666 TRACE [org.jboss.jca.adapters.jdbc.local.LocalManagedConnectionFactory] (JCA PoolFiller) Using properties: {user=sa, password=--hidden--}
      16:02:20,666 DEBUG [org.jboss.jca.core.connectionmanager.pool.idle.IdleRemover] (management-handler-thread - 7) Unregister pool: SemaphoreArrayListManagedConnectionPool@2f5a2102[pool=ExampleDS]
      16:26:04,259 TRACE [org.jboss.jca.core.connectionmanager.pool.strategy.OnePool] (JCA PoolFiller) Filling pool cl=org.jboss.jca.core.connectionmanager.listener.TxConnectionListener@34f0bb27[state=NORMAL managed connection=org.jboss.jca.adapters.jdbc.local.LocalManagedConnection@288f1898 connection handles=0 lastUse=1434353164259 trackByTx=false pool=org.jboss.jca.core.connectionmanager.pool.strategy.OnePool@56a43905 pool internal context=SemaphoreArrayListManagedConnectionPool@5cbd770e[pool=ExampleDS] xaResource=LocalXAResourceImpl@4a97b7f5[connectionListener=34f0bb27 connectionManager=4b18594a warned=false currentXid=null productName=H2 productVersion=@PROJECT_VERSION@ (2012-07-13) jndiName=java:jboss/datasources/ExampleDS] txSync=null]
      (repeat 10 times)
      16:26:11,342 TRACE [org.jboss.jca.core.connectionmanager.TxConnectionManager] (http-/127.0.0.1:8080-1) getManagedConnection interleaving=false , tx=null
      16:26:11,343 DEBUG [org.jboss.jca.core.connectionmanager.pool.idle.IdleRemover] (http-/127.0.0.1:8080-1) Register pool: SemaphoreArrayListManagedConnectionPool@1d4ae61f[pool=ExampleDS] (interval=1800000)
      16:26:11,344 TRACE [org.jboss.jca.core.connectionmanager.pool.strategy.OnePool] (JCA PoolFiller) Filling pool cl=org.jboss.jca.core.connectionmanager.listener.TxConnectionListener@1c706b4d[state=NORMAL managed connection=org.jboss.jca.adapters.jdbc.local.LocalManagedConnection@18949ad1 connection handles=0 lastUse=1434353171343 trackByTx=false pool=org.jboss.jca.core.connectionmanager.pool.strategy.OnePool@56a43905 pool internal context=SemaphoreArrayListManagedConnectionPool@1d4ae61f[pool=ExampleDS] xaResource=LocalXAResourceImpl@44401bf2[connectionListener=1c706b4d connectionManager=4b18594a warned=false currentXid=null productName=H2 productVersion=@PROJECT_VERSION@ (2012-07-13) jndiName=java:jboss/datasources/ExampleDS] txSync=null]
      (repeat 10 times)
      

      In 1.0.31.Final:

      > if (mcp.isEmpty())
      > clearMcpPools.add(mcp);

      In 1.2 branch it looks like already fixed within commit 956af09c8494d4187db24a253e7e37b5ba5d9779 for JBJCA-1135:

      > if (mcp.isEmpty() && !isPrefill() && size > 1)
      > clearMcpPools.add(mcp);

      We probably need to backport "!isPrefill()" to the 1.0/1.1 branch.

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            jpederse@redhat.com Jesper Pedersen
            rhn-support-tkimura Takayoshi Kimura
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              Updated:
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