PQ74639; 4.0.7: Hanging or Lost Threads or wait on writeLock()
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Abstract
When using StatefulSessionBeans to communicate with EJB, the ORB communication with the EJB halts. The JVM™ must be stopped and restarted to get communication resumed.
 
Download Description
PQ74639 resolves the following problem:

USERS AFFECTED:
WebSphere Application Server Developers using the Object Request Broker (ORB) for communications.

PROBLEM DESCRIPTION:
ORB worker threads stay around and do not go away. Sometimes they seem to hang.

This problem can affect the AdminServer or the AppServer, since each of these jvm processes uses ORB communication. The external symptom is that the AppServer or AdminServer jvm process appears to be hung and does not complete ORB communication. If it is the AdminServer process that is experiencing the symptom, the AdminConsole does not start and wscp will not be able to connect to the AdminServer.

The internal symptoms are that the Java™ thread dump will show two or more threads blocked in ORB calls. What is meant by blocked is that the ORB call does not finish. The threads that are typically noticed having this problem are ORB.thread.pool threads. The calls that are usually seen are:

  • IIOPConnection.writeLock
  • IIOPConnection.send

Here is an example of the writeLock:

"ORB.thread.pool:80" (TID:0x3187FBE8, sys_thread_t:0x3CBBBF18, state:CW, native ID:0x614C) prio=5
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java(Compiled Code))
at com.ibm.rmi.util.Condition.wait(Condition.java(Compiled Code))
at com.ibm.CORBA.iiop.IIOPConnection.writeLock(IIOPConnection.java(Compiled Code))
at com.ibm.CORBA.iiop.IIOPConnection.writeLock(IIOPConnection.java:1381)

The hang in send can also be caused if the Orb timeout is infinite. It is also advisable to apply PQ70054 if it is not already included in the WebSphere Application Server version.

Below is an example of a thread with the problem in send:

"ORB.thread.pool:2" daemon prio=5 tid=0x7eeb20 nid=0x16 waiting on monitor 0xecd80000..0xecd819e0
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:415)
at com.ibm.rmi.util.Condition.wait(Condition.java:32)
at com.ibm.CORBA.iiop.IIOPConnection.send(IIOPConnection.java:1501)
at com.ibm.CORBA.iiop.ClientRequestImpl.invoke(ClientRequestImpl.java:522)

RECOMMENDATION:
When WriteLock() receives the state of ABORT, the lock is not released correctly, causing the hanging symptom.
 
Prerequisites
NONE
 
 
Installation instructions
Please review the readme.txt for detailed installation instructions.
 
URL LANGUAGE SIZE(Bytes)
Readme US English 1993
 
Download package
What is DD?
DOWNLOAD RELEASE DATE LANGUAGE SIZE(Bytes) Download Options
PQ74639_Fix 7/15/2004 US English 1077013 FTP DD
 
Technical support
1-800-IBM-SERV (U.S. Only)
 
Problems (APARs) fixed
PQ74639
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Object Request Broker (ORB)
Operating system(s): HP-UX
Software version: 4.0.7
Software edition:
Reference #: 4007484
IBM Group: Software Group
Modified date: Aug 17, 2004