phpstorm - enabling xdebug remote debug makes apache server very slow

Question

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 1

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.