APAR status
Closed as program error.
Error description
PMI infrastructure does not scale well when the URL grows unbounded. When PMI StatisticSet is set to Custom, which enables the PMI webAppModule counters by default. In some cases the high CPU usage may be driven by the PMI webAppModule counters (RequestCount, ConcurrentRequests, and ServiceTime).
Local fix
Disable equestCount, ConcurrentRequests, and ServiceTime URL related Web Application PMI counters, they will not have this problem. It is not usually common, as many customers do not enable these counters in PMI, as it is known to have a performance impact. For more information, please refer to the following Knowledge Center documentation, which lists the impact on enabling Web application counters: https://www.ibm.co m/support/knowledgecenter/en/SSAW57_8.5.5/com.ibm.websphere.nd.m ultiplatform.doc/ae/rprf_datacounter10.html Hence, if the customer wants to continue using PMI, and not experience high CPU usage, without disabling IM, we recommend them to disable the above webAppModules, by following the steps below: 1) In the admin console, on the left hand side, select the following: Monitoring and Tuning -> Performance Monitoring Infrastructure (PMI) 2) Choose the correct application server. 3) Ensure Enable PMI is checked. (I assume it is since you're even seeing an issue with PMI) 4) Click on Custom. (This is a link to a customization area) 5) On the left hand side of the customization area, choose Web Applications. 6) Select URIConcurrentRequests (ID=16), URIServiceTime (ID=17), URIRequestCount (ID=15) and AsyncContext Response Time (ID=19) Choose Disable. 7) Save the changes , re-sync all nodes and restart the server.
Problem summary
**************************************************************** * USERS AFFECTED: All users of IBM WebSphere Application * * Server * **************************************************************** * PROBLEM DESCRIPTION: A high CPU issue may be seen when PMI * * URL * * statistic counters grow unbounded. * **************************************************************** * RECOMMENDATION: * **************************************************************** When the PMI URL statistic counters are enabled for unbounded URLs, a high CPU issue may be encountered. It is not recommended for users to have individual URL statistics enabled for increasing and unbounded URLS (and users may not be able to pinpoint the source of their high CPU issue), so a warning message has been added telling users to disable specific PMI statistic counters after the counter has tracked over 5000 (as a default) different URLs. The value of the default can be changed by setting the system property com.ibm.ws.pmi.maxUniquePmiMetricCount. An example of the warning: CWPMI0109W: Over {0} stats are being tracked for {1}, PMI module {2} id {3}. By tracking a high number of PMI metrics, performance issues can occur. Disable {1}, PMI module {2} ID {3} in the administrative console.
Problem conclusion
The fix for this APAR is targeted for inclusion in fix packs 8.5.5.24 and 9.0.5.15. For more information, see 'Recommended Updates for WebSphere Application Server': https://www.ibm.com/support/pages/node/715553
Temporary fix
Comments
APAR Information
APAR number
PH35234
Reported component name
WEBS APP SERV N
Reported component ID
5724H8800
Reported release
850
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2021-03-10
Closed date
2023-01-05
Last modified date
2023-01-05
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
[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.5","Line of Business":{"code":"LOB45","label":"Automation"}}]
Document Information
Modified date:
06 January 2023