I have been trying to get rid of an error that keeps dumping the following
messages in my Tomcat server logs for sometime now. I posted it on this list
but no one has responded, which I take to mean that this probably is not a
problem for many.
org.*postgresql*.util.PSQLException: An I/O *error* occured while sending to
the backend.
at org.*postgresql*
.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:214)
at org.*postgresql*
.jdbc2.AbstractJdbc2Connection.executeTransactionCommand(AbstractJdbc2Connection.java:621)
at org.*postgresql*
.jdbc2.AbstractJdbc2Connection.rollback(AbstractJdbc2Connection.java:658)
at
org.apache.commons.dbcp.DelegatingConnection.rollback(DelegatingConnection.java:328)
at
org.apache.commons.dbcp.DelegatingConnection.rollback(DelegatingConnection.java:328)
at
org.apache.commons.dbcp.PoolingDriver$PoolGuardConnectionWrapper.rollback(PoolingDriver.java:377)
at org.*dspace*.core.Context.abort(Context.java:356)
at org.*dspace*.core.Context.finalize(Context.java:499)
at java.lang.ref.Finalizer.invokeFinalizeMethod(Native Method)
at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:83)
at java.lang.ref.Finalizer.access$100(Finalizer.java:14)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:160)
Caused by: java.io.IOException: Stream closed
at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:26)
at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:121)
at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:212)
at org.*postgresql*.core.PGStream.flush(PGStream.java:531)
at org.*postgresql*
.core.v3.QueryExecutorImpl.sendSync(QueryExecutorImpl.java:672)
at org.*postgresql*
.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:187)
... 11 more
java.sql.SQLException: Already closed.
at
org.apache.commons.dbcp.PoolableConnection.close(PoolableConnection.java:84)
at
org.apache.commons.dbcp.PoolingDriver$PoolGuardConnectionWrapper.close(PoolingDriver.java:269)
at org.*dspace*
.storage.rdbms.DatabaseManager.freeConnection(DatabaseManager.java:566)
at org.*dspace*.core.Context.abort(Context.java:365)
at org.*dspace*.core.Context.finalize(Context.java:499)
at java.lang.ref.Finalizer.invokeFinalizeMethod(Native Method)
at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:83)
at java.lang.ref.Finalizer.access$100(Finalizer.java:14)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:160)
*dspace*: System startup complete.
In digging I have located what I think is the culprit. In the Context.java
abort method, the connection is rolled back and freed without checking if it
is already closed.
try
{
connection.rollback();
}
catch (SQLException se)
{
log.error(se.getMessage());
se.printStackTrace();
}
finally
{
DatabaseManager.freeConnection(connection);
connection = null;
events = null;
}
If I change the code so that I first check whether the connection is closed,
then I eliminate the errors.
try
{
if (!connection.isClosed())
connection.rollback();
}
catch (SQLException se)
{
log.error(se.getMessage());
se.printStackTrace();
}
finally
{
try
{
if (!connection.isClosed())
DatabaseManager.freeConnection(connection);
}
catch (Exception ex)
{
ex.printStackTrace();
}
connection = null;
events = null;
}
I don't know whether the system performance is improved but I can't imagine
that it can be a good thing to have exceptions thrown regularly. At the
least my Tomcat server log is now more readable.
John
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