Edit report at https://bugs.php.net/bug.php?id=72322&edit=1
ID: 72322
Updated by: nikic@php.net
Reported by: jai at vidyamantra dot com
Summary: High sys CPU usage
-Status: Re-Opened
+Status: Feedback
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:
Is anyone still seeing this issue? At some point we also disabled the use of transparent huge pages
(via madvise rather than mmap), which I think may have been the cause here.
Previous Comments:
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[2017-12-06 11:44:08] pavel2000 at ngs dot ru
Catch the same issue with high sys CPU usage.
Opcache module completely disabled, only php-cli is in use when we see this issue.
Sys CPU usage reduced to "normal" state after command
#echo "never" >/sys/kernel/mm/transparent_hugepage/enabled
OS: Debian 8, PHP packages are from Debian testing.
Current kernel version is
# uname -a
Linux web 3.2.0-4-amd64 #1 SMP Debian 3.2.82-1 x86_64 GNU/Linux
# php7.1 -v
PHP 7.1.11-1 (cli) (built: Oct 27 2017 13:47:15) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2017 Zend Technologies
# php7.1 -m
[PHP Modules]
bcmath
calendar
Core
ctype
curl
date
dom
enchant
exif
fileinfo
filter
ftp
gd
gearman
gettext
gmp
hash
iconv
igbinary
intl
json
libxml
mbstring
mcrypt
memcached
msgpack
mysqli
mysqlnd
openssl
pcntl
pcre
PDO
pdo_mysql
pdo_pgsql
pgsql
Phar
posix
readline
Reflection
session
shmop
SimpleXML
soap
sockets
SPL
standard
sysvmsg
sysvsem
sysvshm
tidy
tokenizer
wddx
xml
xmlreader
xmlwriter
xsl
zip
zlib
[Zend Modules]
------------------------------------------------------------------------
[2017-09-21 03:07:30] jai at vidyamantra dot com
opcache.huge_code_pages is already 0. If we don't use high values at vm.extra_free_kbytes and
vm.min_free_kbytes we face this problem.
------------------------------------------------------------------------
[2017-09-21 02:32:15] wym1 at meitu dot com
set opcache.huge_code_pages = 0 , it will work fine
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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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