PHP Out of Memory Exception

Question

I have a PHP program that will run forever (not a webpage a socket server). After processing over 1000 requests the program eventually crashes due to an out of memory exception.

Here is a link to my project.

Here is a link to my program.

I am not sure why this happens, I have tried using garbage collection functions in the function that processes requests (onMessage) in the program but it does not result in any changes. Any suggestions would be appreciated.

Answer 1

Investing huge amounts of effort, you may be able to mitigate this for a while. But in the end you will have trouble running a non-terminating PHP application.

Check out PHP is meant to die. This article discusses PHP's memory handling (among other things) and specifically focuses on why all long-running PHP processes eventually fail. Some excerpts:

There’s several issues that just make PHP the wrong tool for this. Remember, PHP will die, no matter how hard you try. First and foremost, there’s the issue of memory leaks. PHP never cared to free memory once it’s not used anymore, because everything will be freed at the end — by dying. In a continually-running process, that will slowly keep increasing the allocated memory (which is, in fact, wasted memory), until reaching PHP’s memory_limit value and killing your process without a warning. You did nothing wrong, except expecting the process to live forever. Under load, replace the “slowly” part for "pretty quickly".

There’s been improvements in the “don’t waste memory” front. Sadly, they’re not enough. As things get complex or the load increases, it’ll crash.