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From gnath <gautam_exquis...@yahoo.com>
Subject Dead lock with tomcat-jdbc.jar on Tomcat 6.0.35
Date Fri, 27 Jan 2012 05:38:04 GMT
Hello all,

So we have 2 Linux servers running our application with  Tomcat-6.0.35, JDK 1.6.30. We are
using:
tomcat-jdbc.jar (Verison 1.1.1), 

mysql-connector-java-3.1.12-bin.jar

We have 'removeAbandoned' flag to true in our configuration. We initially had commons-dbcp.jar
1.3 version and as it gave problems, we started using tomcat-jdbc.jar. One of the servers
is working normally, but we saw one issue on the second server. it hasn't been releasing the
connections 
and was consistently growing slowly. So i collected thread dump and i 
saw a deadlock :

Found one Java-level deadlock:
=============================
"catalina-exec-1":
  waiting to lock monitor 0x000000005d7944b8 (object 0x00000005bd522568, a com.mysql.jdbc.Connection),
  which is held by "[Pool-Cleaner]:Tomcat Connection Pool[1-1015483951]"
"[Pool-Cleaner]:Tomcat Connection Pool[1-1015483951]":
  waiting to lock monitor 0x000000005dcdea28 (object 0x00000005bd659ce8, a com.mysql.jdbc.ResultSet),
  which is held by "catalina-exec-1"

Java stack information for the threads listed above:
===================================================
"catalina-exec-1":
        at com.mysql.jdbc.Connection.getCharsetConverter(Connection.java:3177)
        - waiting to lock <0x00000005bd522568> (a com.mysql.jdbc.Connection)
        at com.mysql.jdbc.Field.getStringFromBytes(Field.java:583)
        at com.mysql.jdbc.Field.getName(Field.java:487)
        at com.mysql.jdbc.ResultSet.buildIndexMapping(ResultSet.java:593)
        at com.mysql.jdbc.ResultSet.findColumn(ResultSet.java:926)
        - locked <0x00000005bd659ce8> (a com.mysql.jdbc.ResultSet)
        at com.mysql.jdbc.ResultSet.getInt(ResultSet.java:2401)

"[Pool-Cleaner]:Tomcat Connection Pool[1-1015483951]":
        at com.mysql.jdbc.ResultSet.close(ResultSet.java:736)
        - waiting to lock <0x00000005bd659ce8> (a com.mysql.jdbc.ResultSet)
        at com.mysql.jdbc.Statement.realClose(Statement.java:1606)
        - locked <0x00000005bd522568> (a com.mysql.jdbc.Connection)
        - locked <0x00000005bd5e81c0> (a com.mysql.jdbc.ServerPreparedStatement)
        at com.mysql.jdbc.PreparedStatement.realClose(PreparedStatement.java:1703)
        at com.mysql.jdbc.ServerPreparedStatement.realClose(ServerPreparedStatement.java:901)
        - locked <0x00000005bd525ba0> (a java.lang.Object)
        - locked <0x00000005bd522568> (a com.mysql.jdbc.Connection)
        - locked <0x00000005bd5e81c0> (a com.mysql.jdbc.ServerPreparedStatement)
        at com.mysql.jdbc.Connection.closeAllOpenStatements(Connection.java:2126)
        at com.mysql.jdbc.Connection.realClose(Connection.java:4422)
        at com.mysql.jdbc.Connection.close(Connection.java:2098)
        - locked <0x00000005bd522568> (a com.mysql.jdbc.Connection)
        at org.apache.tomcat.jdbc.pool.PooledConnection.disconnect(PooledConnection.java:320)



Please help us on this. Could it be a problem with tomcat-jdbc.jar? What should be our next
steps? I have read some article saying tomcat-jdbc.jar would give better performance than
commons dbcp pool.


Thanks
Mime
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