Edit report at https://bugs.php.net/bug.php?id=72322&edit=1
ID: 72322
Comment by: wym1 at meitu dot com
Reported by: jai at vidyamantra dot com
Summary: High sys CPU usage
Status: Re-Opened
Type: Bug
Package: Performance problem
Operating System: Centos 6.8 x64
PHP Version: 7.0.7
Block user comment: N
Private report: N
New Comment:
set opcache.huge_code_pages = 0 , it will work fine
Previous Comments:
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[2017-01-20 09:16:02] jai at vidyamantra dot com
It has been two days since when we modified following kernel values.
vm.extra_free_kbytes
vm.min_free_kbytes
Since then, we are not facing this problem. It appears the problem is with the way how PHP7
allocates or uses memory.
We were able to reproduce this problem on two entirely different and isolated production servers
that had no problem with php5 but this problem started within few hours after we upgraded to PHP7.
Our servers have 256GB of RAM and this issue appears when free memory is low. Clearing system
buffers/cache (echo 3 > /proc/sys/vm/drop_caches) always fixes this problem but Linux gradually
starts caching files from disk and free memory starts dropping.
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[2016-12-25 04:22:19] php-bugs at lists dot php dot net
No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Re-Opened". Thank you.
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[2016-12-20 07:33:31] jai at vidyamantra dot com
Tested on version 7.0.10 and problem is still present. It happens more often when system memory is
near full (swap still empty), for e.g. system has 256GB of RAM and this happens when about only 10GB
of RAM is used. At this stage, sys time increase significantly.
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[2016-12-17 14:51:26] nikic@php.net
Do you still experience this problem with a current version of PHP 7? I'd assume the issue is
due to huge pages (see https://bugs.php.net/bug.php?id=70984), which are
no longer enabled by default.
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[2016-06-03 06:58:47] jai at vidyamantra dot com
Description:
------------
Upgrade to php 7 and saw high CPU usage.
http://serverfault.com/q/780555/126826 (CPU
graphs and sar output).
==== PHP 7 ====
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
31.24 0.000973 1 1204 munmap
15.25 0.000475 0 1523 3 open
12.52 0.000390 0 4012 216 lstat
7.70 0.000240 0 1363 mmap
5.81 0.000181 0 1528 close
5.36 0.000167 1 219 getdents
5.01 0.000156 0 1618 stat
4.33 0.000135 0 1433 535 access
3.69 0.000115 0 3256 fstat
2.47 0.000077 0 547 write
1.67 0.000052 0 224 uname
1.22 0.000038 0 276 sendto
0.87 0.000027 0 638 read
0.83 0.000026 0 752 flock
0.58 0.000018 0 760 poll
==== PHP 5 ====
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
23.32 0.001103 5 206 sendto
17.45 0.000825 1 1650 getdents
14.95 0.000707 0 4638 651 stat
10.59 0.000501 0 3181 1708 access
7.27 0.000344 0 4918 172 lstat
6.07 0.000287 0 2391 3 open
4.76 0.000225 1 314 poll
3.66 0.000173 0 1526 munmap
2.56 0.000121 0 4633 fstat
2.11 0.000100 0 1704 mmap
1.54 0.000073 1 97 rename
1.40 0.000066 0 923 2 lseek
1.08 0.000051 0 2395 close
0.80 0.000038 0 562 49 ioctl
0.68 0.000032 0 831 read
0.57 0.000027 0 406 write
0.34 0.000016 0 141 mprotect
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Edit this bug report at https://bugs.php.net/bug.php?id=72322&edit=1