Unresponsive thread in Tomcat

Question

Env: Tomcat 5.x on Java 1.5.x on Windows using OracleJDBC driver on Oracle 9i

The problem: I have a thread which is in RUNNABLE state. It doesn't seem to complete -ever.

How do I investigate this further ? This is reproducible quite easily.

This thread is basically trying to insert some data

Update: This insert is happening in a synchronized block

This is what I got from the thread dump...

"http-9080-Processor24" daemon prio=6 tid=0x0b20bc00 nid=0x1274 runnable [0x0d55e000..0x0d55fc94]
java.lang.Thread.State: RUNNABLE
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.read(Unknown Source)
    at oracle.net.ns.Packet.receive(Unknown Source)
    at oracle.net.ns.DataPacket.receive(Unknown Source)
    at oracle.net.ns.NetInputStream.getNextPacket(Unknown Source)
    at oracle.net.ns.NetInputStream.read(Unknown Source)
    at oracle.net.ns.NetInputStream.read(Unknown Source)
    at oracle.net.ns.NetInputStream.read(Unknown Source)
    at oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1099)
    at oracle.jdbc.driver.T4CMAREngine.unmarshalSB1(T4CMAREngine.java:1070)
    at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:478)
    at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:216)
    at oracle.jdbc.driver.T4CPreparedStatement.executeForRows(T4CPreparedStatement.java:955)
    at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:10580)
    - locked <0x02c10078> (a oracle.jdbc.driver.T4CPreparedStatement)
    - locked <0x03dceb08> (a oracle.jdbc.driver.T4CConnection)
    at org.apache.commons.dbcp.DelegatingStatement.executeBatch(DelegatingStatement.java:294)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)

Answer 1

RN:

If you have a java core dump file, did you try to use HPROF tools from Java SE 5 ? I usually used this tool as a simple way to find out where a problem was in the source codes. If it does not help, I will probably use a profiler tool. Please correct me if it is wrong for your question.

I hope it helps.

Tiger.

Answer 2

Looks like your application is executing oracle.jdbc.driver.OraclePreparedStatement.executeBatch(), which seems to be waiting (forever?) for a NetInputStream to actually return something.

So, is it possible the query/statement being run is never returning? Is it possible your database is hanging? Or it could be possible you've encountered some sort of bug in the Oracle JDBC driver - are you on the most up-to-date version?

You should probably also check if your JDBC driver allows you to specify configurations for connection/query timeouts, etc, to prevent the driver for waiting forever and ever.

Answer 3

One of the reasons why the batch statement may not return is because of locks on table - held because the changes were not properly committed by previous running queries.

If that is the case - you should review the code where all autoCommit(true) / autoCommit(false) has been set and if rollback has been used in exception handling clauses and commit otherwise.

You could also check the profile dump from Visual VM tool - that comes in handy while doing testing for a running application in development env. It gives a complete drill down of method call execution.