What is "<Cycle 1>" an indication of in Xdebug?

profiling xdebug kcachegrind
DTest picture DTest · Sep 15, 2011 · Viewed 9.6k times · Source

I have an xdebug profile on a php script that I parsed with kcachegrind. Here is a screenshot showing that the most time spent inside any given function was spent inside <cycle 1> and the top 'Callers' were made from 'include' and 'include_once' in index.php.

kcachegrind of xdebug profile showing cycle 1

This profile was run during a stress-test using apache 'ab' so there were many concurrent connections occurring.

What does <cycle 1> indicate on an xdebug profile?

Answer

osgx picture osgx · Sep 20, 2011

It is heuristic cycle detection. You can turn it off from toolbar or from menu "View->Detect cycles" or "View->Do cycle detection".

Cycle is something like recursion, both direct ( f() -> f() -> f() where -> means call ) and indirect ( f()->g()->f()->g()->f())

Callgring format (used in kcachegrind) is not saving full call stack, it stores only pairs caller-callee and it may be hard to restore longer cycles from this information

Related questions

Is there any KCacheGrind alternative for Mac Os X outta there?

I'm looking for a KCacheGrind alternative, or at least a binary package for Mac Os X? I'd to use KCacheGrind with XDebug for PHP, but Mac Os X is the right environnement here... Thank you Edit: I know I can …

Read More
How to trigger XDebug profiler for a command line PHP script?

XDebug offers the configuration directive "xdebug.profiler_enable_trigger" that allows to activate profiling by passing the GET or POST parameter "XDEBUG_PROFILE" when calling a script via HTTP. This is handy if you don't want profiling for ALL of …

Read More
Can I manually say on xdebug profiler to start profiling in specific place?

I already have enabled xDebug profiling in my XAMPP installation and it works fine. Now I like to ask if there is a way to say from within my source code when to start profiling with xDebug. More specific, I'd …

Read More