#20745 [Opn->Fbk]: socket_accept() in blocking mode doesn't handle signal interrupts
ID: 20745
Updated by: sniper@php.net
Reported By: polone@townnews.com
-Status: Open
+Status: Feedback
Bug Type: Sockets related
Operating System: Linux
PHP Version: 4.2.3
New Comment:
Please try using this CVS snapshot:
http://snaps.php.net/php4-latest.tar.gz
For Windows:
http://snaps.php.net/win32/php4-win32-latest.zip
Previous Comments:
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[2002-12-01 07:59:34] polone@townnews.com
The socket_accept() function doesn't appear to handle kernel level
system interrupts. This is a problem because PHP scripts written to use
pcntl_signal() won't be executed while socket_accept() is in blocking
mode. THAT is a problem because the script can't be killed with:
kill -s SIGUSR1 [pid]
and can't reap zombie processes when SIGCHLD is given (not that is much
of a problem on Linux, since you can use SIG_IGN).
A workaround I've made is to set a socket to non-blocking mode:
socket_set_nonblock($hSocket);
And then use a while loop like so:
while (($hClient = @socket_accept($hSocket)) === false) {
// If this is a real error, we need to handle it. Unfortunately,
in this
// event we just die() essentially.
if (!is_resource($hSocket)) {
error_log(socket_strerror(socket_last_error($hSocket)));
exit;
}
// We need to sleep for one second so that CPU isn't absorbed
with this
// process. This may seem clunky, but select() doesn't appear to
work
// correctly with accept() in PHP in blocking mode (that is
EINTR does
// not appear to work correctly), thus preventing signals from
being
// received. This, in effect, makes the process unkillable. This
is the
// workaround, for the moment.
sleep(1);
}
While this works, it would be much better if it just returned when a
system interrupt is given like the C-equivalent does. This works
because the system can't receive messages from the kernel because it
isn't blocking.
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Thread (10 messages)