Re: spawning a process that uses pipes - doesn't terminate when webpage download is canceled

On Sun, 2009-05-31 at 08:52 -0500, flint wrote: > sent this before, don't know if it went through... someone please reply if > it went, even if they don't know answer?... > > so here's the scenario.. > > I have a site that uses php with a database to offer sound files to > users using streaming methods. > > the request page has options, allowing the user to modify the sound > file in various ways, before having it sent to them > > Here's the problem: > > The method i'm using to feed the data to the user is to run the source > file through various piped commands, with the resulting audio being > dumped to stdout, and then using passthru in php to get that data to > the enduser. > > here's an example, for serving an MP3 with its pitch/speed changed by sox: > > passthru("lame --quiet --decode \"" . $in_file . "\" - | " . > "sox -V -S -t wav - -t wav - speed " . $speed_factor . " | " . > "lame --quiet " . $lame_params . " - -"); > > This works just fine, except the problem is if the end user aborts the > transfer (e.g. stops playback in the media player, cancels download of > the mp3, whatever) then it leaves behind both the sox process and the > decoder LAMe process along with the sh that's running them. the only > process that exits is the final encoding lame process. If the sound > file runs to completion, everythign exits properly. > > But this obviously means enough "cancelling" of downloads means the > server ends up with a huge batch of stuck processes! And I even tried > simply killing the 'host' sh process, and the lame and sox processes > remain anyway. The only way I've been able to deal with this is > manually killing the lame and sox processes directly. > > is there any way I can make this work, such so that if the user > cancels the transfer, all relavent processes are killed rather than > just the single process that's feeding output into php? Use something else to pass the data back to the user... popen() comes to mind or proc_open(). Then disable auto abort on user disconnect via ignore_user_abort(). Then after sending periodic data chunks, check the user connection status via connection_aborted(). If your script finds that the user has aborted, then kill all the processes in the pipeline from the PHP script before finally aborting the PHP script itself. Cheers, Rob. -- http://www.interjinn.com Application and Templating Framework for PHP