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Date: Tue, 5 Feb 2008 06:32:09 -0800 (PST)
From: "Andrus Adamchik (JIRA)" <jira@apache.org>
To: issues@commons.apache.org
Subject: [jira] Commented: (DBCP-244) Connection socket hangs sporadically
 in DBCP 1.2.2 but not 1.2.1
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    [ https://issues.apache.org/jira/browse/DBCP-244?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12565756#action_12565756 ] 

Andrus Adamchik commented on DBCP-244:
--------------------------------------

I am observing a similar behavior with MySQL 5.0, dbcp-1.2.1, pool-1.2.... Also no visible deadlock in a thread dump. It happens once every few weeks, but usually simultaneously on multiple applications, so I suspect it is caused by temporary network outages... The problem of course is that the pool never recovers.

Stuck threads look like this:

btpool0-873" prio=10 tid=0x01001c50 nid=0x26a3 runnable [0x679fc000..0x679ffaf0]
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:129)
        at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:113)
        at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:160)
        at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:188)
        - locked <0xab4f6b20> (a com.mysql.jdbc.util.ReadAheadInputStream)
        at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1902)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2351)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2862)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1571)
        at com.mysql.jdbc.ServerPreparedStatement.serverExecute(ServerPreparedStatement.java:1124)
        - locked <0xac8430b0> (a java.lang.Object)
        at com.mysql.jdbc.ServerPreparedStatement.executeInternal(ServerPreparedStatement.java:676)
        at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1030)
        - locked <0xac8430b0> (a java.lang.Object)
        - locked <0xa69343f0> (a com.mysql.jdbc.ServerPreparedStatement)
        at org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:92)
        at org.apache.cayenne.access.jdbc.SelectAction.performAction(SelectAction.java:72)


DBCP pool is wrapped in a Cayenne decorator, but this is still a DBCP pool with the following settings:

cayenne.dbcp.maxActive=8
cayenne.dbcp.minIdle=1
cayenne.dbcp.maxIdle=4
cayenne.dbcp.validationQuery=select 1 from nhldb.division limit 1;
cayenne.dbcp.testWhileIdle=true

Can't even say that DBCP is here to blame, but still figured I provide this data point.


> Connection socket hangs sporadically in DBCP 1.2.2 but not 1.2.1
> ----------------------------------------------------------------
>
>                 Key: DBCP-244
>                 URL: https://issues.apache.org/jira/browse/DBCP-244
>             Project: Commons Dbcp
>          Issue Type: Bug
>    Affects Versions: 1.2.2
>         Environment: Fedora Core 3, MySQL 4.1.22. with the latest driver (5.07). Exceptions only occur in the "job processing" JVM, which sits idle for long periods of time and occasionally wakes up to interact with the database.
>            Reporter: ori
>             Fix For: 1.3
>
>
> I think I've traced an exception to DBCP's code.
> Communication with the database is hanging sporadically in a production environment. If I don't set the socketTimeout property on the underlying connection, it will hang forever. With the socketTimeout property, I get the following exception:
> -------
> com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception:
> ** BEGIN NESTED EXCEPTION **
> java.net.SocketTimeoutException
> MESSAGE: Read timed out
> STACKTRACE:
> java.net.SocketTimeoutException: Read timed out
>        at java.net.SocketInputStream.socketRead0(Native Method)
>        at java.net.SocketInputStream.read(SocketInputStream.java:129)
>        at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:113)
>        at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:160)
>        at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:188)
>        at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1994)
>        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2411)
>        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2916)
>        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1631)
>        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1723)
>        at com.mysql.jdbc.Connection.execSQL(Connection.java:3250)
>        at com.mysql.jdbc.Statement.executeUpdate(Statement.java:1355)
>        at com.mysql.jdbc.Statement.executeUpdate(Statement.java:1270)
>        at org.apache.commons.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:228)
> ...
> -------
> It always happens in an infrequently used JVM (not an app server handling frequent connections). So it's likely the offending connection was asleep for a long time before the exception occurs. 
> I've confirmed that this issue only occurs using 1.2.2 and not 1.2.1. I've been looking through the changelogs but can't find anything that would cause this behavior.
> Does somebody familiar with the codebase have any idea what change (1.2.1->1.2.2) could be causing this behavior? 
> Thanks

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