PK32201; 6.0.2.17: OutOfMemory Due to large DRS messages

Download Description

PK32201 resolves the following problem:

ERROR DESCRIPTION:
In the PUSH replication mode IBM® WebSphere® Application Server Dynacache sends replication messages that are large, which frequently causes the Java Virtual Machines in a clustered environment to exhaust their heaps, resulting in Out Of Memory errors and heap dumps. The fix allows the user to specify a few custom properties enable Dynacache to chunk these messages thereby sending only a few cache entries at a time in a message, resulting in smaller objects and helping these heap exhaustion issues.

LOCAL FIX:

PROBLEM SUMMARY

USERS AFFECTED:
WebSphere Application Server users of dynamic cache who configure cache replication in PUSH mode.

PROBLEM DESCRIPTION:
In the PUSH replication mode Dynacache sends large replication messages which frequently cause the
Java Virtual Machiness in a clustered environment to exhaust their heaps, resulting in OutOfMemory errors and heap dumps.

RECOMMENDATION:
None

In the PUSH replication mode Application Server's, Dynacache service sends replication messages that are large, which frequently causes the servers in a clustered environment to exhaust their java virtual machine heaps, resulting in OutOfMemory errors and heap dumps. PK32201 relieves this issue by allowing the user to control the size (in terms of number of cache entries) of the sent messages.

PROBLEM CONCLUSION:
The batch size of the replication data can now be configured using the following custom properties:

com.ibm.ws.cache.CacheConfig.cachePercentageWindow: Specifies a limit on the number of cache entries sent by the Data Replication Service in terms of the percentage of total cache in memory. Default value: 2% of the no. of entries in the cache Scope: configurable per cache instance.

com.ibm.ws.cache.CacheConfig.cacheEntryWindow: Specifies a limit on the total number of cache entires sent by the Datat Replication Service in terms of number of entries. Default value: 50 entries Scope: configurable per cache instance.

com.ibm.ws.CacheConfig.batchUpdateMilliseconds: Specifies a batch update frequency in terms of milliseconds. Setting this property will result in Dynacache processing updates more frequently, and thus reducing the payload size. Default Value: 1000 ms (1 s).

The fix for this APAR is currently targeted for inclusion in cumulative fix 5.1.1.14, and fixpacks 6.0.2.19, and 6.1.0.7.

Please note that there are two separate iFixes for this APAR:
- 6.0.2.15-17-WS-WASND-IFPK32201.pak for base Application Server version 6.0.2.15.

- 6.0.2.17-WS-WASND-IFPK32201.pak for base Application Server version 6.0.2.17.

Please refer to the recommended updates page for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980