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diff --git a/README.md b/README.md new file mode 100644 index 0000000..2d5a721 --- /dev/null +++ b/README.md @@ -0,0 +1,264 @@ +# php-memprof + +php-memprof profiles memory usage of PHP scripts, and especially can tell which +function has allocated every single byte of memory currently allocated. + +This is different from measuring the memory usage before and after a +function call: + +``` php +<?php + +// script 1 + +function a() { + $data = file_get_contents("huge-file"); +} + +a(); + +$profile = memprof_dump_array(); + +``` + +In script 1, a before/after approach would designate file_get_contents() as huge +memory consumer, while the memory it allocates is actually freed quickly after +it returns. When dumping the memory usage after a() returns, the memprof +approach would show that file_get_contents() is a small memory consumer since +the memory it allocated has been freed at the time memprof_dump_array() is +called. + + +``` php +<?php + +// script 2 + +function a() { + global $cache; + $cache = file_get_contents("huge-file"); +} + +a(); + +$profile = memprof_dump_array(); +``` + +In script 2, the allocated memory remains allocated after file_get_contents() +and a() return, and when memprof_dump_array() is called. This time a() and +file_get_contents() are shown as huge memory consumers. + +## How it works + +See [INTERNALS.md][7] + +## Dependencies + + * [Judy Library][3] (e.g. libjudy-dev or judy package) + * C Library with [malloc hooks][1] (optional; allows to track persistent allocations too) + +## Install + +### Using PECL + + pecl install memprof + +### Manually + +Download the source and run the following commands in the source directory: + + phpize + ./configure + make + make install + +## Loading the extension + +The extension can be loaded on the command line, just for one script: + + php -dextension=memprof.so script.php + +Or permanently, in php.ini: + + extension=memprof.so + +## Usage + +Memprof can be enabled during script execution by calling ``memprof_enable()``. + +Then the memory usage can be dumped by calling one of the ``memprof_dump_`` +functions. Both tell which functions allocated all the currently allocated +memory. + +Example: + +``` +<?php + +if (function_exists('memprof_enable')) { + memprof_enable(); +} + +do_some_work(); + +if (function_exists('memprof_enable')) { + memprof_dump_callgrind(fopen("/tmp/callgrind.out", "w")); +} +``` + +### memprof_enabled() + +Returns whether memprof is enabled. + +### memprof_enable() + +Enables memprof and start tracking memory allocations. Note: any memory +allocation made before this call is ignored. + +### memprof_disable() + +Disables memprof and forget previous allocations. + +### memprof_dump_callgrind(resource $stream) + +The memprof_dump_callgrind function dumps the current memory usage to a stream +in callgrind format. The file can then be read with tools such as +[KCacheGrind][2] or [QCacheGrind][6]. + +``` php +<?php +memprof_dump_callgrind(fopen("output", "w")); +``` + +Here is a KcacheGrind screenshot: + +![KCacheGrind screenshot](http://img820.imageshack.us/img820/5530/screenshot3kve.png) + +### memprof_dump_pprof(resource $stream) + +The memprof_dump_pprof function dumps the current memory usage to a stream in +[pprof][4] format. + +``` php +<?php +memprof_dump_pprof(fopen("profile.heap", "w")); +``` + +The file can be visualized using [google-perftools][5]'s [``pprof``][4] tool. + +Display annotated call-graph in web browser or in ``gv``: + +``` +$ pprof --web profile.heap +$ # or: +$ pprof --gv profile.heap +``` + +![pprof call-graph screenshot](http://img707.imageshack.us/img707/7697/screenshot3go.png) + +Output one line per function, sorted by own memory usage: + +``` +$ pprof --text profile.heap +``` + +### memprof_dump_array() + +``` php +<?php +$dump = memprof_dump_array(); +``` + +The dump exposes the following information: + + * Inclusive and exclusive memory usage of functions (counting only the memory + that has is still in use when memprof_dump_array is called) + * Inclusive and exclusive blocks count of functions (number of allocated; + counting only the blocks that are still in use when memprof_dump_array is + called) + * The data is presented in call stacks. This way, if a function is called from + multiple places, it is possible to see which call path caused it to leak the + most memory + +Example output: + + Array + ( + [memory_size] => 11578 + [blocks_count] => 236 + [memory_size_inclusive] => 10497691 + [blocks_count_inclusive] => 244 + [calls] => 1 + [called_functions] => Array + ( + [main] => Array + ( + [memory_size] => 288 + [blocks_count] => 3 + [memory_size_inclusive] => 10486113 + [blocks_count_inclusive] => 8 + [calls] => 1 + [called_functions] => Array + ( + [a] => Array + ( + [memory_size] => 4 + [blocks_count] => 1 + [memory_size_inclusive] => 10485825 + [blocks_count_inclusive] => 5 + [calls] => 1 + [called_functions] => Array + ( + [b] => Array + ( + [memory_size] => 10485821 + [blocks_count] => 4 + [memory_size_inclusive] => 10485821 + [blocks_count_inclusive] => 4 + [calls] => 1 + [called_functions] => Array + ( + [str_repeat] => Array + ( + [memory_size] => 0 + [blocks_count] => 0 + [memory_size_inclusive] => 0 + [blocks_count_inclusive] => 0 + [calls] => 1 + [called_functions] => Array + ( + ) + ) + ) + ) + ) + ) + [memprof_dump_array] => Array + ( + [memory_size] => 0 + [blocks_count] => 0 + [memory_size_inclusive] => 0 + [blocks_count_inclusive] => 0 + [calls] => 1 + [called_functions] => Array + ( + ) + ) + ) + ) + ) + ) + +## Todo + + * Support for tracking persistent (non-zend-alloc) allocations when libc + doesn't have malloc hooks + +[1]: https://www.gnu.org/software/libc/manual/html_node/Hooks-for-Malloc.html#Hooks-for-Malloc +[2]: http://kcachegrind.sourceforge.net/html/Home.html +[3]: http://judy.sourceforge.net/index.html +[4]: https://google-perftools.googlecode.com/svn/trunk/doc/heapprofile.html +[5]: https://google-perftools.googlecode.com/ +[6]: https://www.google.com/search?q=qcachegrind +[7]: https://github.com/arnaud-lb/php-memory-profiler/blob/master/INTERNALS.md + |