[
https://issues.apache.org/jira/browse/DBCP-595?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Phil Steitz closed DBCP-595.
----------------------------
Resolution: Not A Problem
Don't mean to be blunt / dismissive with the close here. But this does not
look like a DBCP bug and it would be better to discuss on the mailing list any
changes to behavior. See [~ggregory] 's nice summary there on why we do not
force close connections on fatal SQL exceptions - basically drivers don't
consistently return codes that a generic library can count on.
I would definitely recommend reporting or trying to find and patch the code
that checks out connections from the pool and does not close them on fatal
exception paths. That would impact a lot of other users. One way to find this
is to turn abandoned connection logging.
> Connection pool can be exhausted when connections are killed on the DB side
> ---------------------------------------------------------------------------
>
> Key: DBCP-595
> URL: https://issues.apache.org/jira/browse/DBCP-595
> Project: Commons DBCP
> Issue Type: Bug
> Affects Versions: 2.11.0
> Reporter: Dénes Bodó
> Priority: Critical
> Labels: deadlock, robustness
> Attachments: ReproOneThread-jstack-minIdle.txt,
> ReproOneThread-jstack_when_create.txt, ReproOneThread-jstack_when_stuck.txt,
> ReproOneThread-screenshot_when_create-newCreateCount_gt_localMaxTotal.png
>
>
> Apache Oozie 5.2.1 uses OpenJPA 2.4.2 and commons-dbcp 1.4 and commons-pool
> 1.5.4. These are ancient versions, I know.
> h1. Description
> The issue is that when due to some network issues or "maintenance work" on
> the DB side (especially PostgreSQL) which causes the DB connection to be
> closed, it results exhausted Pool on the client side. Many threads are
> waiting at this point:
> {noformat}
> "pool-2-thread-4" #20 prio=5 os_prio=31 tid=0x00007faf7903b800 nid=0x8603
> waiting on condition [0x000000030f3e7000]
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x000000066aca8e70> (a
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
> at
> org.apache.commons.pool2.impl.LinkedBlockingDeque.takeFirst(LinkedBlockingDeque.java:1324)
> {noformat}
> According to my observation this is because the JDBC driver does not get
> closed on the client side, nor the abstract DBCP connection
> _org.apache.commons.dbcp2.PoolableConnection_ .
> h1. Repro
> (Un)Fortunately I can reproduce the issue using the latest and greatest
> commons-dbcp 2.11.0 and commons-pool 2.12.0 along with OpenJPA 3.2.2.
> I've just created a Java application to reproduce the issue:
> [https://github.com/dionusos/pool_exhausted_repro] . See README.md for
> detailed repro steps.
> h1. Kind of solution?
> To be honest I am not really familiar with DBCP but with this change I
> managed to make my application more robust:
> {code:java}
> diff --git a/src/main/java/org/apache/commons/dbcp2/PoolableConnection.java
> b/src/main/java/org/apache/commons/dbcp2/PoolableConnection.java
> index 440cb756..678550bf 100644
> --- a/src/main/java/org/apache/commons/dbcp2/PoolableConnection.java
> +++ b/src/main/java/org/apache/commons/dbcp2/PoolableConnection.java
> @@ -214,6 +214,10 @@ public class PoolableConnection extends
> DelegatingConnection<Connection> impleme
> @Override
> protected void handleException(final SQLException e) throws SQLException
> {
> fatalSqlExceptionThrown |= isFatalException(e);
> + if (fatalSqlExceptionThrown && getDelegate() != null) {
> + getDelegate().close();
> + this.close();
> + }
> super.handleException(e);
> }{code}
> What do you think about this approach?
> Is it a completely dead-end or we can start working on it in this direction?
> Do you agree that the reported and reproduced issue is a real one and nut
> just some kind of misconfiguration?
>
> I am lost at this point and I need to move forward so I am asking for
> guidance here.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
