CPU hogs ignoring SIGTERM (unkillable processes)

From: Ulrich Windl
Date: Mon Nov 15 2004 - 07:01:47 EST


Hello,

today I've discovered a programming error in one of my programs (that's fixed
already). When trying to replace the binary, I found out that the processes seem
unaffected by a plain "kill": They just continue to consume CPU. However, a "kill
-9" terminates them. ist that intended behavior? I guess not. Here are some facts:

top - 12:51:33 up 145 days, 22:20, 1 user, load average: 8.06, 8.77, 9.51
Tasks: 85 total, 9 running, 76 sleeping, 0 stopped, 0 zombie
Cpu(s): 57.4% user, 1.9% system, 0.0% nice, 40.6% idle
Mem: 191192k total, 90716k used, 100476k free, 19004k buffers
Swap: 132088k total, 29140k used, 102948k free, 37580k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ Command
28042 daemon 25 0 92 32 28 R 13.2 0.0 163:59.44 extractMIME
29435 daemon 25 0 92 32 28 R 13.2 0.0 156:34.27 extractMIME
31211 daemon 25 0 92 32 16 R 13.2 0.0 145:12.22 extractMIME
156 daemon 25 0 92 32 16 R 13.2 0.0 135:24.49 extractMIME
4079 daemon 25 0 92 32 16 R 13.2 0.0 109:48.36 extractMIME

This is about 3 minutes after executing this command:
kill 27176 27457 28042 29435 31211 156 4079

This happened for both SUSE kernels, old and new:
m1 2.4.20-4GB #1 Mon Mar 17 17:54:44 UTC 2003
m2 2.6.5-7.111-default #1 Wed Oct 13 15:45:13 UTC 2004

And no, the C program does not install any signal handler. If interested I can
provide the binary together with sample parameters to execute the loop.

Regards,
Ulrich

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