It is known that XDebug has a negative impact on performance, but what happens when you try to debug a Flow3 application can be something between absolutely surprising and totally annoying. But one after another.
XDebug is my every day tool. I use it not only for debugging, but for regular development as well. I simply enjoy the benefit to always know which variables are available in the current scope (Typo3 globals, anyone?), I don’t need to recall nested array structures, I can evaluate my code on the fly and so on. So naturally, on my dev XDebug is always enabled and listening, both for PHP SAPI or Webserver.
Working on my first Flow3 project, I suddenly found myself waiting over 30 minutes for the Cache to rebuild after flushing it manually. Running the application on a different machine worked ok, so it was obvious that the issue was somewhere in my setup. Wtf?
So I did what a normal XDebug user would do – let’s profile that damn thing! I realized the core problem as I found dozends of sometimes quite huge Cachegrind files in my output directory. What the heck, there must be really some serious action going on (and it does – see box below)! So I disabled XDebug for the moment, and voilà – the Cache was rebuild within seconds.
If you have not worked with Flow3 before you have to know that Flow3 actually requires cached class files because of the use of Aspect-oriented programming (AOP). In short, Flow3 scans the code files of the packages whether certain rules (the so called Aspects, defined via Annotations) apply, and changes the code in the classes according to the Aspect. Doing this for every request would be obviously insane, so the results are cached. We suddenly find our good old PHP scripts in some way being compiled.
There is a nice article about Flow3 and AOP to be found here which describes it more in detail.
Flow3 luckily has some advanced file monitoring which, when you work in Development context, makes it unnecessary to clear the whole cache manually every time you change a class, and rebuilding the cache for one class only will work within a reasonable amount of time even with XDebug turned on. Nevertheless sometimes you will need to flush the whole cache, and then you’re doomed. En-/Disabling XDebug in the php.ini manually would be too cumbersome (for me). So there has to be a more convenient solution.
How to debug Flow3 applications and stay sane
Here’s with what I ended up: I disabled XDebug for PHP via CLI by default, and enable it only when I need it using the “php -d” switch:
php -dxdebug.remote_autostart=On -dxdebug.remote_enable=On ./flow
Not a very easy one to remember, but we’re getting close. Why not put this into a separate shell script? Yes, why not. I called it “flowdebug”, and it is located in the project root (where the original flow command is located).
php -dxdebug.remote_autostart=On -dxdebug.remote_enable=On ./flow "$@"
As you can see I also put the environment variables needed to start the debugging session in that script.
So from now on, when I want to debug my Flow3 application, I simply use