Red Hat Bugzilla – Bug 119216
Massive slowdown, disk activity in CPU bound Java program
Last modified: 2007-11-30 17:07:01 EST
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Description of problem:
The document given by the URL has a complete description of the
problem. (I will also try to attach this file to the bug report.)
Briefly, a particular CPU intensive Java program that ran fine under
Redhat 9 using a variety of Java versions exhibits *massive* slowdowns
under RHEL. Also, when using Sun JDKs, there is tons of disk activity
when the program runs. (It should be almost entirely CPU bound, and
is CPU bound on Redhat 9.)
I have tried setting the LD_ASSUME_KERNEL environment variable to
2.4.1, and it does not help. The program in question is single threaded.
I listed the IBM JDK in this bug report, but the program doesn't run
correctly on RHEL with any JVM I have tried.
The same program runs perfectly well on other architectures (such as
Mac OS X and Solaris), so I do not believe that it is a bug in the
The problem seems to be partially affected by SMP - on a two processor
system, the program makes almost no progress, while on a uniprocessor
system running the same version of RHEL, the slowdown is about 3x, but
it eventually completes.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
Steps to reproduce are given in the problem description file referred
to by the URL.
Actual Results: Massive slowdown, tons of disk activity, interactive
responsiveness of other processes greatly reduced, process extremely
slow to respond to interrupt signal from tty.
Expected Results: The program should be CPU bound, and complete in a
few minutes (given the run parameters and input described).
Created attachment 98883 [details]
Complete description of the problem, and how to reproduce.
Sometime between March 26th (when I posted this bug
originally) and June 22nd, the problem went away.
I'm pretty sure one of the kernel updates must have
fixed it, although I have no idea which one.
Java programs execute fine now.