locking problem in jdbc driver?

I am seeing the following problem, where a thread holding a java  lock
seems to be blocking another query. I suspect the the thread holding the java lock
may be waiting for a DB lock to be freed by the second one. I am pasting the
relevant parts of the java stack trace. All threads shown here are operating on
the same table, and they are all parts of transactions involving multiple tables.
deadlock detection is set for 1 sec and no dedlocks are reported by postgres.

"http-192.168.0.22-8080-6" daemon prio=10 tid=0x083bcc00 nid=0x2fc4 waiting for monitor entry [0x8c9fd000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:169)
        - waiting to lock <0x959ebed0> (a org.postgresql.core.v3.QueryExecutorImpl)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:351)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:255)
        at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
        at sun.reflect.GeneratedMethodAccessor61.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        ...

"http-192.168.0.22-8080-3" prio=10 tid=0x8ea6e000 nid=0x2f3e runnable [0x8c9ad000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:129)
        at org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:135)
        at org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:104)
        at org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:73)
        at org.postgresql.core.PGStream.ReceiveChar(PGStream.java:255)
        at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1165)
        at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:191)
        - locked <0x959ebed0> (a org.postgresql.core.v3.QueryExecutorImpl)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:351)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:305)
        at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeUpdate(NewProxyPreparedStatement.java:105)
        ...

"http-192.168.0.22-8080-5" daemon prio=10 tid=0x0900c000 nid=0x2f53 runnable [0x8c56d000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:129)
        at org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:135)
        at org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:104)
        at org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:73)
        at org.postgresql.core.PGStream.ReceiveChar(PGStream.java:255)
        at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1165)
        at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:191)
        - locked <0x959e0800> (a org.postgresql.core.v3.QueryExecutorImpl)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:351)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:305)
        at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeUpdate(NewProxyPreparedStatement.java:105)
        at sun.reflect.GeneratedMethodAccessor94.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        ...
"http-192.168.0.22-8080-4" daemon prio=10 tid=0x08eae000 nid=0x2f4f runnable [0x8c5be000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:129)
        at org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:135)
        at org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:104)
        at org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:73)
        at org.postgresql.core.PGStream.ReceiveChar(PGStream.java:255)
        at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1165)
        at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:191)
        - locked <0x98004510> (a org.postgresql.core.v3.QueryExecutorImpl)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:351)
        at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:305)
        at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeUpdate(NewProxyPreparedStatement.java:105)
        at sun.reflect.GeneratedMethodAccessor94.invoke(Unknown Source)
        ...

Sherif