Fixes are available
8.0.0.3: WebSphere Application Server V8.0 Fix Pack 3
8.0.0.4: WebSphere Application Server V8.0 Fix Pack 4
8.0.0.5: WebSphere Application Server V8.0 Fix Pack 5
8.0.0.6: WebSphere Application Server V8.0 Fix Pack 6
8.0.0.7: WebSphere Application Server V8.0 Fix Pack 7
8.0.0.8: WebSphere Application Server V8.0 Fix Pack 8
8.0.0.9: WebSphere Application Server V8.0 Fix Pack 9
8.0.0.10: WebSphere Application Server V8.0 Fix Pack 10
8.0.0.11: WebSphere Application Server V8.0 Fix Pack 11
8.0.0.12: WebSphere Application Server V8.0 Fix Pack 12
8.0.0.13: WebSphere Application Server V8.0 Fix Pack 13
8.0.0.14: WebSphere Application Server V8.0 Fix Pack 14
8.0.0.15: WebSphere Application Server V8.0 Fix Pack 15
APAR status
Closed as program error.
Error description
Websphere Application Server Version 8.0.0.0 Java Version 1.6.0 Linux, version 2.6.18-238.el5 Problem Description: Webcontainer leaks memory when application uses the Asynchronous invocation API. From the heapdumps we see the Webcontainer code is holding these scheduled threadpool Executor objects. com/ibm/ws/webcontainer/async/AsyncContextImpl$ExecutorFieldHold er 1,036,864,512 (77%) [88] 6 java/util/concurrent/ScheduledThreadPoolExecutor 1,036,863,920 (77%) [16] 1 java/util/concurrent/ScheduledThreadPoolExecutor$DelayedWorkQueu e 1,036,863,904 (77%) [24] 3 java/util/concurrent/DelayQueue 1,036,863,720 (77%) [24] 1 java/util/PriorityQueue 1,036,863,696 (77%) [213,000] 36,537 array of java/lang/Object 191,923,400 (14%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task Basically, the webcontainer code: com/ibm/ws/webcontainer/async/AsyncContextImpl$ExecutorFieldHold er is holding around 53,008 of these scheduled threadpool Executor objects. Expanding one of these out we see the composition: 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 53,008 (0%) [40] 2 java/util/concurrent/ScheduledThreadPoolExecutor$ScheduledFuture Task 52,968 (0%) [48] 2 java/util/concurrent/FutureTask$Sync 52,920 (0%) [16] 1 java/util/concurrent/Executors$RunnableAdapter 52,904 (0%) [16] 2 com/ibm/ws/webcontainer/async/AsyncTimeoutRunnable 52,832 (0%) [104] 10 com/ibm/ws/webcontainer/async/WSAsyncContextImpl 26,600 (0%) [56] 7 com/ibm/ws/webcontainer/srt/SRTServletRequest 25,920 (0%) [144] 10 com/ibm/ws/webcontainer/srt/SRTServletRequest$SRTServletRequestH elper 24,824 (0%) [48] 3 java/io/BufferedReader 16,400 (0%) [16,400] 0 char[] 8,376 (0%) [24] 2 java/io/InputStreamReader 8,376 (0%) [24] 2 java/io/InputStreamReader 648 (0%) [40] 1 java/util/HashMap 200 (0%) [40] 1 java/util/Hashtable 104 (0%) [40] 1 java/util/Hashtable
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: IBM WebSphere Application Server version * * 8.0 user of Asynchronous Servlet. * **************************************************************** * PROBLEM DESCRIPTION: Heavy usage of asynchronous servlet * * applications can cause an Out of * * Memory (OOM) exception. * **************************************************************** * RECOMMENDATION: * **************************************************************** A scheduled task is created and added to a queue before dispatching to a different resource in the asynchronous servlet application. When the dispatched asynchronous servlet is completed or timed out, its task is canceled and supposedly removed from the queue by the Java Virtual Machine (JVM) worker threads. When the application server is under load, the worker threads might be too busy and do not remove the canceled tasks in a timely manner; thus causing them to be accumulated in the queue and holding up the memory. Eventually the OOM can occur.
Problem conclusion
The WebContainer code was modified to actively remove the canceled tasks from the queue instead of waiting for the JVM worker threads to purge them. There are two new WebContainer custom properties which are introduced by this APAR: com.ibm.ws.webcontainer.asyncMaxSizeTaskPool = 5000 (default) com.ibm.ws.webcontainer.asyncPurgeInterval = 30000 (default in milliseconds) The WebContainer will purge the queue once per interval when the size of the queue is greater than the max pool size. Please refer to the following technote for instructions on enabling WebContainer custom properties: http://www.ibm.com/support/docview.wss?rss=180&uid=swg21284395 The fix for this APAR is currently targeted for inclusion in fixpack 8.0.0.3 Please refer to the recommended updates page for delivery information: http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
Temporary fix
Comments
APAR Information
APAR number
PM51151
Reported component name
WEBS APP SERV N
Reported component ID
5724H8800
Reported release
800
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2011-10-28
Closed date
2011-11-30
Last modified date
2012-03-09
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
WEBS APP SERV N
Fixed component ID
5724H8800
Applicable component levels
R800 PSY
UP
[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.0","Line of Business":{"code":"LOB45","label":"Automation"}}]
Document Information
Modified date:
28 October 2021