Edit report at https://bugs.php.net/bug.php?id=73265&edit=1
ID: 73265
User updated by: spam2 at rhsoft dot net
Reported by: spam2 at rhsoft dot net
Summary: PHP7 dramatically slower in some cases
Status: Open
Type: Bug
Package: Performance problem
Operating System: Linux
-PHP Version: 7.0.11
+PHP Version: 7.0.14
Block user comment: N
Private report: N
New Comment:
what i can assure you is that with 7.0.14 things got *much* worser and the system dropped down below
4 per second with "ab -c 20" and is raising OOM killers because each apache preforker in
htop is showing 120 MB to 160 MB RES memory usage in htop while with PHP5.6 it was constantly around
50 MB
this can not be opcache (or at least should not be) because shared memory typically is not counted
as "resident" for each process
Requests per second: 3.85 [#/sec] (mean)
Time per request: 5198.089 [ms] (mean)
Time per request: 259.904 [ms] (mean, across all concurrent requests)
Transfer rate: 55.88 [Kbytes/sec] received
Previous Comments:
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[2016-10-07 14:05:31] spam2 at rhsoft dot net
configuration is 100% identical, even the CFLAGS and ./configure as well as RPM sub-pckaging, two
days before the upgrade i "backported" the RPM-SPEC and deployed a new 5.5.26 build
something eats twice CPU it seems
a second VM on the same host has exactly twice requests per second with PHP7 which is caused by the
fact the VM has 12 instead of only 6 cores
well, we will downgrade a developer machine on monday and try to compare xdebug outputs with PHP5
and PHP7, IMHO that should show changes in how expensive parts of the application are and lead to
find the critical code paths
hopefully we can nail that down to specific native php-functions which would lead in isolted loop
cases and reprocuder-sample code, i guess the php developers are also curious in which bordercases
the results go in the exactly wrong direction
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[2016-10-07 13:40:08] nikic@php.net
Assuming you've already considered all the obvious causes (configuration and especially
opcache), I'd suggest running your CMS through "perf record" + "perf
report" and see what the top elements look like (on both versions). Additionally it
wouldn't hurt to use strace to check whether there are any significant differences in
IO/syscalls.
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[2016-10-07 11:58:40] spam2 at rhsoft dot net
Description:
------------
we have two different inhouse cms-systems, while one is 46% faster with PHP7 the other one sucks
terrible - are there things known by developers which are internally slower now while most other
become afster and should be avoided?
my first guess was mbstring but it's not, i have setup a cli environment with both php-versions
+ modules and a shell wrapper "php5" and "php7" and until now i am not able to
find any isolted peice of code with a PHP7 slowdown
it looks like others see similar results
https://laracasts.com/discuss/channels/general-discussion/is-it-just-me-or-is-php-7-slow
unluckily the cms developed by me is the faster one and now both have a difference of factor 30-36
Requests per second: 107.24 [#/sec] (mean)
Time per request: 279.741 [ms] (mean)
Time per request: 9.325 [ms] (mean, across all concurrent requests)
Transfer rate: 1531.03 [Kbytes/sec] received
Requests per second: 56.30 [#/sec] (mean)
Time per request: 532.864 [ms] (mean)
Time per request: 17.762 [ms] (mean, across all concurrent requests)
Transfer rate: 803.75 [Kbytes/sec] received
Test script:
---------------
impossible to provide :-(
Expected result:
----------------
have at least the same performance but not half
Actual result:
--------------
massive slowdown
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Edit this bug report at https://bugs.php.net/bug.php?id=73265&edit=1