Red Hat Bugzilla – Bug 104724
top occasionally consumes 1 CPU
Last modified: 2007-11-30 17:06:53 EST
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User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)
Description of problem:
At random intervals, maybe once a month across 30 servers, I'm alerted to high
CPU utilization on a server, and find a "top" command using 100% of a CPU.
Typically the command has been running for several hours, and is running as a
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Can't reproduce. Happens randomly, infrequently.
Servers are Compaq DL360-G2s w/ 2 CPUs, 4 GB RAM. Running 2.4.9-e.9smp.
Can you reproduce this using 3.1.15 version?
It appears that sometimes the kernel will fail to sent SIGHUP
to the foreground process group when the session leader dies.
I've seen it after doing "su" in an xterm and then killing
the xterm. This is one way to cause the problem you're seeing.
This also happens with procps-2.0.17-10 from RHEL AS 3 U3.
The primary problem is that top(1) doesn't terminate when a read of stding
returns an EOF indication. Specifically, after a "read(0, buf, 1)" returns
zero top(1) continues running. The secondary problem is that certain login
shells (such as the real ksh, not pdksh) don't propagate SIGHUP correctly.
This bug is filed against RHEL2.1, which is in maintenance phase.
During the maintenance phase, only security errata and select mission
critical bug fixes will be released for enterprise products. Since
this bug does not meet that criteria, it is now being closed.
For more information of the RHEL errata support policy, please visit:
If you feel this bug is indeed mission critical, please contact your
support representative. You may be asked to provide detailed
information on how this bug is affecting you.