[DBCP-298] CLONE -Connection socket hangs sporadically in DBCP 1.2.2 but not 1.2.1

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.2.2
• Fix Version/s: 1.3

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.

• Assignee: Unassigned
• Reporter: Denson Kim
• Created: 27/Jul/09 18:49
• Updated: 03/Aug/09 18:32
• Resolved: 03/Aug/09 18:32

Description

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

Issue Links

• is a clone of: DBCP-244 Connection socket hangs sporadically in DBCP 1.2.2 but not 1.2.1