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#1 2013-01-02 11:00:42

tcn
Member
Registered: 2011-09-30
Posts: 24

random 100% CPU kernel when running java

Hi!

This happens sporadically but far too often to ignore. When running java (1.7.0_10, x64, standard kernel) I notice full utilization of all cores; and it's kernel time.

The machine quickly freezes so it's kind of hard to investigate...

$ strace -p 15775                                                           
Process 15775 attached
futex(0x7f6e7b8ca9d0, FUTEX_WAIT, 15776, NULL) =

Somebody else having this issue?

thx
tcn

Last edited by tcn (2013-01-02 13:09:50)

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#2 2013-01-03 09:47:21

tcn
Member
Registered: 2011-09-30
Posts: 24

Re: random 100% CPU kernel when running java

Appears to be fixed with 3.6.11 (?). Plus: code is running much faster now.

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#3 2013-01-03 15:04:03

tcn
Member
Registered: 2011-09-30
Posts: 24

Re: random 100% CPU kernel when running java

Bummer, just happend again.

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#4 2013-01-03 20:11:55

dr_te_z
Member
From: Zoetermeer, the Netherlands
Registered: 2006-12-06
Posts: 154

Re: random 100% CPU kernel when running java

Sounds like a garbage collecting thing. Gc can log its activities. See if the times match your own observations.


Somewhere between "too small" and "too large" lies the size that is just right.
- Scott Hayes

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#5 2013-01-05 18:16:27

tcn
Member
Registered: 2011-09-30
Posts: 24

Re: random 100% CPU kernel when running java

perf:

65.84%  [kernel]                                            [k] _raw_spin_lock_irqsave

strace:

[pid 24947] futex(0x7f52702edd28, FUTEX_WAKE_PRIVATE, 1) = 0
[pid 24947] futex(0x7f52702edd54, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, {1357409542, 1448000}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
[pid 24947] futex(0x7f52702edd28, FUTEX_WAKE_PRIVATE, 1) = 0
[pid 24947] futex(0x7f52702edd54, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, {1357409542, 11552000}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
[pid 24947] futex(0x7f52702edd28, FUTEX_WAKE_PRIVATE, 1) = 0
[pid 24947] futex(0x7f52702edd54, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, {1357409542, 21683000}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
[pid 24947] futex(0x7f52702edd28, FUTEX_WAKE_PRIVATE, 1) = 0
[pid 24947] futex(0x7f52702edd54, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, {1357409542, 31788000}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
[pid 24947] futex(0x7f52702edd28, FUTEX_WAKE_PRIVATE, 1) = 0
[pid 24947] futex(0x7f52702edd54, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, {1357409542, 41914000}, ffffffff <unfinished ...>
[pid 24938] <... futex resumed> )       = -1 ETIMEDOUT (Connection timed out)
[pid 24938] futex(0x7f5270102428, FUTEX_WAKE_PRIVATE, 1) = 0
[pid 24938] futex(0x7f5270102454, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, {1357409542, 89241000}, ffffffff <unfinished ...>
[pid 24947] <... futex resumed> )       = -1 ETIMEDOUT (Connection timed out)

Last edited by tcn (2013-01-06 17:37:36)

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#6 2013-01-05 18:18:08

tcn
Member
Registered: 2011-09-30
Posts: 24

Re: random 100% CPU kernel when running java

One more googling: https://bugzilla.redhat.com/show_bug.cgi?id=888380

Last edited by tcn (2013-01-06 17:37:48)

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#7 2013-01-15 06:59:01

guy
Member
Registered: 2012-08-25
Posts: 4

Re: random 100% CPU kernel when running java

Same issue here. I experience the same behaviour from kernel version 3.6.8 up to the current one : "3.6.11-1-ARCH #1 SMP PREEMPT Tue Dec 18 08:57:15 CET 2012 x86_64 GNU/Linux".

I tried OpenJDK 1.7 and Oracle JDK with same results. Changing the JVM allocated memory helped a bit by reducing the blocked phase duration. BTW, on Fedora, some users experience the same issue : http://forums.fedoraforum.org/showthrea … 246&page=2

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