View Issue Details
|ID||Project||Category||View Status||Date Submitted||Last Update|
|0001668||Xdebug||Profiling||public||2019-05-20 14:34||2019-07-12 09:49|
|Status||resolved||Resolution||no change required|
|Target Version||Fixed in Version|
|Summary||0001668: Just installing xdebug slows php (both apache OR cli) down 6 to 12 x|
|Description||On a Centos 7.x machine, php7.3.|
The mere installation of xdebug has the effect described in subject. When installing, the file /etc/php.d/xdebug.ini is created, which loads libxdebug.so. However, all of xdebug debug and tracing functions are still disabled. The overhead incurred is dramatic, from 6 x up to almost two orders of magnitude, both in web AND CLI execution. strace-ing a CLI script shows an unordinate amount of time is spent syscalling getimeofday - so it may be related to profiling.
This also happens on CentOS6, php56...
|Steps To Reproduce||(1) Run the attached script. Record the output|
(2) yum install php-pecl-xdebug
(3) rerun script, note the increased execution time
Actual slowdown is code dependent - 10-20 times is not uncommon for wordpress sites.
bench.php (3,167 bytes)
||A debugger does work, so that makes it slow down the request. The benchmark you provided is not representative of a real workload of PHP, and might give skewed results. I hope to address some of the performance impacts in Xdebug 3, but as there is no actionable point in this issue report, I am closing it.|
||I agree that any debug code/extension will have a impact. What this issue points at, however, is that the its mere presence (module installed, unconfigured) slows down a site of amounts that can be above 10x. Slow downs of this magnitude are (in my experience) unexpected when not actively tracing/debugging the code. The benchmark is obviously a toy, but the effect is consistent with what can be witnessed on live sites. At the moment, I have been forced to nuke xdebug from all the servers under my company's administration (the production ones, at least).|
|2019-05-20 14:34||alforg||New Issue|
|2019-05-20 14:34||alforg||Tag Attached: performance|
|2019-05-20 14:34||alforg||File Added: bench.php|
|2019-06-28 11:22||derick||Assigned To||=> derick|
|2019-06-28 11:22||derick||Status||new => resolved|
|2019-06-28 11:22||derick||Resolution||open => no change required|
|2019-06-28 11:22||derick||Note Added: 0005043|
|2019-07-12 09:49||alforg||Note Added: 0005057|