enabling xdebug remote debug makes apache server very slow
If I enable xdebug by settting xdebug.remote_enable=1, the apache server becomes very slow; once I change the setting to 0, it's normal.
I found a same question here: XDebug really slow, but the answer isn't helpful. I didn't enable profiling:
xdebug.profiler_enable=0
xdebug.auto_trace = 0
xdebug.trace_output_dir = /tmp/xdebug
xdebug.trace_output_name = trace.%c
I checked there's nothing under /tmp/xdebug folder.
When xdebug remote debug is enabled and I enable debug listening in PHPStorm, it takes a short while to stop at the breakpoint, but not as slow as disabling phpstorm debug listening.
My environment is: php + apache + xdebug on local centos VM, my mysql db and PHPStorm are on Windows desktop for development. MySQL is not slow.
Appreciate for help.
Answer
In my case this was caused by having
xdebug.remote_autostart = 1
set in php.ini. That causes xdebug to try to connect to remote debugger on every request. I had some PHP handled styles, auto_preppend_file and other PHP files in the request and for each of them it waited approximately 2secs, which added up to sth. like 15 seconds or so. Setting
xdebug.remote_autostart = 0
solved the problem completely. xdebug connects only when debug cookie is present. Please note you need to remove the debug cookie/param if you are not in debug session for this fix to work.
Here is my config that I use to setup xdebug.