Increasing nesting function calls limit

Question

There is one very bad limit in PHP: if you call some function a1() that calls a2(), that calls a3... so when a99() will call a100() you will see

Fatal error: Maximum function nesting level of '100' reached, aborting!

Is there any way to increase the limit of 100 nesting calls to 500 or 10000?

This is critical for me because I'm developing an event-based system with a lot of callbacks.

• Ignacio Vazquez-Abrams: 100 seems a little excessive, even for an event framework.
• Abel: @Ignacio: it's quite simple, even if the focus is on an event framework, to have a recursive function that needs a much higher nesting level. Tens of thousands (or even millions) is not uncommon in such scenario's.
• Gujarat Santana: stackoverflow.com/a/36440027/2652524 I solve mine using this answer
• lilHar: @IgnacioVazquez-Abrams If you're doing functional programming instead of object-oriented or procedural, 100 easily is a drop in the bucket. And considering many PHDs in the field recommend using functional over OOP or proc, really, you should always be prepared to have lots of recursive functions.

Answer 1

This error message comes specifically from the XDebug extension. PHP itself does not have a function nesting limit. Change the setting in your php.ini:

xdebug.max_nesting_level = 200

or in your PHP code:

ini_set('xdebug.max_nesting_level', 200);

As for if you really need to change it (i.e.: if there's a alternative solution to a recursive function), I can't tell without the code.

• SkaJess: I had the same problem. My max_nesting_level was set to 100 but in my case, in some cases, it's possible to have 1000 recursive calls. So, I set to 10000 to avoid this xdebug error. In all cases, it always better than let PHP with no limit.
• M. Reza Nasirloo: If you don't have this xdebug.max_nesting_level = 100 option in your php.ini just paste that in.
• Enrique Quero: @Pedram The correct way to copy that in a php ini file is in /etc/php5/apache2/conf.d/20-xdebug.ini, not in the normal php.ini. Just a good practice
• netcoder: @EnriqueQuero Depends on the system and OS.
• user2928048: It works! No matter if you use XDebug or not, neither if you comment out line in php.ini. I explicitly used: ini_set('xdebug.max_nesting_level', -1)

Answer 2

Do you have Zend, IonCube, or xDebug installed? If so, that is probably where you are getting this error from.

I ran into this a few years ago, and it ended up being Zend putting that limit there, not PHP. Of course removing it will let you go past the 100 iterations, but you will eventually hit the memory limits.

Answer 3

Personally I would suggest this is an error as opposed to a setting that needs adjusting. In my code it was because I had a class that had the same name as a library within one of my controllers and it seemed to trip it up.

Output errors and see where this is being triggered.