WebSphere High CPU

High CPU on WebSphere Application Server WebSphere Support Team technical resolutions to common problems with High CPU.

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High CPU

High CPU occurs when the total available CPU resources on a system are utilized above a specific threshold (generally >80%) or to the point that system operations and/or application performance are significantly and negatively impacted. A system running WebSphere Application Server may experience high CPU usage from one or more applications running on WebSphere, from other standalone applications, or from system operations. High CPU from anywhere on the system can impact performance everywhere on the system. To determine the cause of high CPU, several factors must first be well understood:

How much CPU usage is being observed/reported (and by what tool)?

How much CPU usage is expected during normal behavior?

Is the CPU high for a brief period (spike) or sustained for a longer time?

Is the CPU being used by a single process or multiple processes?How much CPU usage is being observed/reported (and by what tool)?

Within the process(es) utilizing CPU, is the CPU being used by a single thread or multiple threads?

The high CPU MustGather scripts included in the links below offer a convenient way to collect system data and thread data from WebSphere processes during a high CPU event. Using the output from these scripts, WebSphere support can determine how much CPU is in use on the system, and track usage to specific processes and/or threads. Then, the call stacks of the threads can be used to identify which code is executing and responsible for the increased CPU usage. See the MustGather page specific to your operating system for more information.

CPU Starvation

A message in the WebSphere SystemOut.log like the one below may indicate that JVM thread scheduling delays are occurring for this process:

[10/15/20 12:34:56:789 EDT] 0000047a CoordinatorCo W HMGR0152W: CPU Starvation detected. Current thread scheduling delay is 9 seconds.

This message may occur even when plenty of CPU resources are available. Please see the following technical note for additional information and steps to resolving the problem:

HMGR0152W: CPU Starvation detected messages in SystemOut.log

MustGathers

MustGather: Performance, hang, or high CPU issues with WebSphere Application Server on Linux

MustGather: Performance, hang, or high CPU issues with WebSphere Application Server on AIX

MustGather: Performance, Hang, or High CPU Issues on Windows

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