IBM Support

High CPU / Hang on java.util.HashMap.findNonNullKeyEntry() due to non-thread-safe usage of HashMap

Troubleshooting


Problem

High CPU or hang symptoms may be observed on java.util.HashMap.findNonNullKeyEntry when a HashMap is utilized in a non-thread-safe manner. This is an unsafe coding practice that can occur at any level of development when using the HashMap API: application, application server, third party module, etc. The following will outline how to identify the problematic code and some possible methods to resolve the issue.

Symptom

High CPU or hung threads with an executing stack similar to the following:


    at java.util.HashMap.findNonNullKeyEntry()
    at java.util.HashMap.getEntry()
    at java.util.HashMap.get()
    at com.xyz.methodABC()
    ...
or
    at java.util.HashMap.findNonNullKeyEntry()
    at java.util.HashMap.putImpl()
    at java.util.HashMap.put()
    at com.xyz.methodABC()
    ...

The specific stack may vary.

As a more general symptom of this issue, the executing stack will show the problematic code calling a method within the HashMap API which will in turn call the findNonNullKeyEntry() method.

[{"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Business Unit":{"code":"BU048","label":"IBM Software"},"Component":"Not Applicable","Platform":[{"code":"PF002","label":"AIX"},{"code":"PF010","label":"HP-UX"},{"code":"PF016","label":"Linux"},{"code":"PF027","label":"Solaris"},{"code":"PF033","label":"Windows"}],"Version":"8.0;7.0","Edition":"Base;Express;Network Deployment","Line of Business":{"code":"LOB77","label":"Automation Platform"}}]

Log InLog in to view more of this document

This document has the abstract of a technical article that is available to authorized users once you have logged on. Please use Log in button above to access the full document. After log in, if you do not have the right authorization for this document, there will be instructions on what to do next.

Document Information

Modified date:
03 March 2025

UID

swg21597581

Page Feedback