PM09935; 7.0.0.9: high cpu usage with dynacache disk offload

Download Description

PM09935 resolves the following problem:

ERROR DESCRIPTION:
High CPU usage with dynaCache disk offload

When a customer tested with dynacache disk offload, the CPU usage was very high for managing dependenceId. Tprof shows that the CPU usage on HTODDependencyTable is increasing a lot.

LOCAL FIX:
N/A

PROBLEM SUMMARY

USERS AFFECTED:
All users of IBM WebSphere Application Server V7.0 using the disk offload feature of dynacache along with dependency IDs.

PROBLEM DESCRIPTION:
Performance decreases as the size of the disk cache increases.

RECOMMENDATION:
None

Dynacache uses a HashMap to maintain the relationship between dependency IDs and the associated cache entry on disk. As the size of the disk cache grows the HashMap also grows and the longer it takes to iterate through the HashMap.

PROBLEM CONCLUSION:
The algorithm that iterates through the HashMap has been modified to perform better.

The fix for this APAR is currently targeted for inclusion in
fix pack 7.0.0.11. Please refer to the Recommended Updates
page for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980