Red Hat Bugzilla – Bug 892212
javac 100% CPU usage with transparent huges pages defrag enable
Last modified: 2013-01-07 08:51:26 EST
Description of problem:
Ever since the 3.5.x kernels, a java build can bring all CPU cores to 100% usage making a system virtually unusable during the build process.
The problem only seems to manifest itself after the system has been running (and used) for some time (a few hours).
Disabling transparent hug page defrag (echo never > /sys/kernel/mm/transparent_hugepage/defrag) fixes the problem.
The problem did not occur with the 3.4.x kernels and since I haven't changed Java versions in some time, it would seem that transparent huge pages are the problem.
Version-Release number of selected component (if applicable):
3.6.x kernels also have this problem
Steps to Reproduce:
1. Run a time-consuming maven build on a system that has been up and used for a few hours.
All CPU cores go to 100%
System "hangs" until build complete
Random CPU usage
System does not "hang"
I have only really noticed the problem with java builds so it may be that the problem only manifests itself with javac and not java.
The java version where I first noticed this was with Oracle's 1.6.0_30.
Please note that I mistakenly stated that the problem started with the 3.5 series of kernels. It actually started with the 3.6 series.
*** This bug has been marked as a duplicate of bug 879801 ***