Since no one developed a reproducible test case it is, unfortunately,
difficult to say whether this bug is resolved. We moved to a 2.6.35
series kernel and stopped seeing this particular problem (although we
have seen other problems that are eerily similar). All of the
information to reproduce the
Matt,
That's definitely in line with what we're seeing. Not to beat a dead
horse, and I am not a kernel hacker (so I apologize for any naivety),
etc... but that's basically what led me to believe the
CLOCK_PROCESS_CPUTIME_ID timers, top issues, and other CPU time
monitoring may be relevant here.
Hey Matt,
I ran it once while the system was idle:
https://gist.github.com/fb35566354afc442bf2d
And then again in a tight loop with a 50ms sleep while I locked the
system up, in the hopes of catching something interesting just before or
during the period when the system was locked:
https://gist.g
Starting irqbalance (without rebooting) on a node in a state where
fork() will hang does not help.
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https://bugs.launchpad.net/bugs/708920
Title:
Strange 'fork/clone' blocking behavior u
Matt,
Still no way to reproduce deterministically. I've just been running
variations of the test I posted above, writing to /dev/null and setting
timer signals. At some point the tests/system start hanging.
irqbalance is not running on any of the test instances that are hanging
(it appears to be
Also, potentially related, the 2.6.32 kernels seem to sometimes drop
timer signals for CLOCK_PROCESS_CPUTIME_ID and continue to report
unusual process CPU times in system monitoring tools like top and via
the proc filesystem. I can reproduce the signal behavior with this
program: https://gist.githu
Fat fingered that kernel version. Should be 2.6.32-311-ec2.
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https://bugs.launchpad.net/bugs/708920
Title:
Strange 'fork/clone' blocking behavior under high cpu usage on EC2
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I am able to reproduce this behavior on an instance running kernel
version 2.3.32-311 using ami-f8f40591. As with the older kernel, new
instances don't immediately exhibit symptoms.
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https:
We're still working on a way to repro this on a new instance. Meanwhile,
we're moving forward with testing on the newer 2.6.32 kernel and on
Maverick's 2.6.35 kernel.
One observation we have made is that if we run the libctest in a loop
(`while :; do ./libctest; done`) on 2.6.32 it will eventually
We are running ami-fd4aa494 with 2.6.32-305-ec2 in us-east. I'll see
what I can do about setting up a couple nodes with the more recent
2.6.32 kernel build and report back.
We've already started running a few Maverick instances with
2.6.35-24-virtual, and so far they appear to be more stable.
Unfo
The node we were working on this morning was:
vendor_id : GenuineIntel
cpu family : 6
model : 26
model name : Intel(R) Xeon(R) CPU X5550 @ 2.67GHz
stepping: 5
cpu MHz : 2666.760
cache size : 8192 KB
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