High CPU usage in io.undertow.servlet.spec.ServletPrintWriter.close() on JBoss EAP 7.x/8.0.x

Solution Verified - Updated 28 Mar 2025

Environment

Red Hat JBoss Enterprise Application Platform (EAP)
- 7.x
- 8.0.x

Issue

JBoss EAP reaches a point of high CPU and we have to restart to clear it. High CPU consumers are shown on default task request processing threads in calls like below:

"default task-1" #175 prio=5 os_prio=0 tid=0x000055ff6ad45800 nid=0x23858c runnable [0x00007f89967fd000]
   java.lang.Thread.State: RUNNABLE
    at sun.nio.cs.UTF_8$Encoder.encodeLoop(UTF_8.java:693)
    at java.nio.charset.CharsetEncoder.encode(CharsetEncoder.java:579)
    at io.undertow.servlet.spec.ServletPrintWriter.close(ServletPrintWriter.java:104)
    at io.undertow.servlet.spec.ServletPrintWriterDelegate.close(ServletPrintWriterDelegate.java:81)
    at io.undertow.servlet.spec.HttpServletResponseImpl.closeStreamAndWriter(HttpServletResponseImpl.java:491)
    at io.undertow.servlet.spec.HttpServletResponseImpl.responseDone(HttpServletResponseImpl.java:586)
    at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:328)
    ...(snip)...

Resolution

Update to EAP 7.4.20+ and EAP 8.0.5+

Root Cause

This issue has been reported as the following JIRAs:
- For EAP 7.4.x: This content is not included.JBEAP-27599 fixed in EAP 7.4.20
- For EAP 8.0.x: This content is not included.JBEAP-27703 fixed in EAP 8.0.5
- Upstream Undertow: This content is not included.UNDERTOW-2425

SBR

Webservers

Product(s)

Red Hat JBoss Enterprise Application Platform

Components

jbossas

Category

Troubleshoot

Tags

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