Memory leak in TcpServer due to PHP stream_context_create memory leak

[lucasnetau]

Hi @clue @WyriHaximus @SimonFrings , I wanted to bring to your attention an internal PHP memory leak (php/php-src#10885) I found which has been affecting me with TcpServer (Specifically through react-child-process-messenger + react/filesystem).

Essentially for each instance of TcpServer, PHP was allocating 720+ bytes that was never released until shutdown, seems to have always existed since PHP4 days https://3v4l.org/XBaaP

The good news is the PHP team quickly provided a patch which has been merged into PHP8.1, 8.2, Master so the next releases will have a fix. It may be useful to add some documentation to TcpServer of this issue for memory constrained environments where there is a high churn of TcpServer instances.

[WyriHaximus]

So this only becomes an issue if you rapidly create temporary socket servers and shut them down again, correct? Also looking at that PHP issue, well done!

[lucasnetau]

@WyriHaximus Yes, In my use case the services are writing out a state file every 1 second. So each second there is a Filesystem putContents to a temp file followed by a rename. This is using Reach Filesystem Child Process, EIO is unusable per the previous tickets opened.

react-child-process-messenger makes good use of TcpServer to do the RPC work, so when doing file operations you rapidly leak memory.

[WyriHaximus]

@lucasnetau Thank you for confirming my thoughts on how this was leaking 👍.

[SimonFrings]

@lucasnetau I agree with @WyriHaximus, thanks for your work on this one 👍

In my opinion it is not necessary to add documentation for this to the TcpServer, this is not your everyday use case when it comes to creating and running a socket server, so it might be misleading to some users.

Great job on the memory leak tho!

[SimonFrings]

Update: The memory leak on PHP's side has been fixed via PHP 8.2.5 and PHP 8.1.18. This doesn't seem to be a bug in ReactPHP, so I will change the label of this ticket and close it, as it seems like everything in here has been answered.

Thanks again to @lucasnetau for reporting this 👍