Undertow multi-part upload can potentially leak file descriptors

Solution Verified - Updated

Environment

  • Red Hat JBoss Enterprise Application Platform (EAP)
    • 7.1.x
    • 7.2.1

Issue

  • When Too many open files occurred, there are a lot of FDs like as follows in lsof results. And those continues to remain.
COMMAND    PID  USER   FD      TYPE             DEVICE  SIZE/OFF      NODE NAME
...
java    14293 jboss 2022r      REG              253,0         0 123123411 /PATH_TO/undertow3910449410434351231upload (deleted)
java    14293 jboss 2023r      REG              253,0     12311 321232114 /PATH_TO/undertow1123943802489403213upload (deleted)
java    14293 jboss 2024r      REG              253,0     12311 298237411 /PATH_TO/undertow3190321842317483219upload (deleted)

Resolution

Upgrading EAP 7.2.1 or later.

As a temporary measure, increasing FD and restart EAP periodically.
But it needs to upgrade 7.2.1 to resolve fundamentally.

Root Cause

This issue has reported as Content from issues.jboss.org is not included.JBEAP-16176 / Content from issues.jboss.org is not included.UNDERTOW-1474.
If using multi-part file uploading in web application, Undertow has potential to leak file descriptor by this bug.
This issue was fixed on 7.2.1 and later.

Diagnostic Steps

When getting lsof -p <PID>, you can see the following FD increasing and remaining.

/PATH_TO/undertow1123943802489403213upload (deleted)
SBR
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