Signals in Extensions

19 years ago by Michael B Allen — view source

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I have an extension that interfaces with a library that sets a signal
handler for some common signals. In particular the library forks processes
and does socket writes so it needs to be able to handle SIGCHLD and
SIGPIPE. It also registers some other signals for debugging purposes. Can
I anticipate any kinds of problems from this? Does the Zend engine use
any signals in particular?

Thanks,
Mike

19 years ago by Sara Golemon — view source

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I have an extension that interfaces with a
library that sets a signal handler for some
common signals. In particular the library
forks processes and does socket writes
so it needs to be able to handle SIGCHLD
and SIGPIPE. It also registers some other
signals for debugging purposes. Can I
anticipate any kinds of problems from this?
Does the Zend engine use any signals in particular?

It's not PHP/Zend you should be afraid of... the interpreter goes a long way
towards avoiding the use of signals because it's designed to run on
<whatever> webserver and that webserver may or may not try to use signals in
one way or another. If you're using the CGI SAPI you might be safe, other
than that.... Best of luck to ya.

19 years ago by Rasmus Lerdorf — view source

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Sara Golemon wrote:

I have an extension that interfaces with a
library that sets a signal handler for some
common signals. In particular the library
forks processes and does socket writes
so it needs to be able to handle SIGCHLD
and SIGPIPE. It also registers some other
signals for debugging purposes. Can I
anticipate any kinds of problems from this?
Does the Zend engine use any signals in particular?

It's not PHP/Zend you should be afraid of... the interpreter goes a long way
towards avoiding the use of signals because it's designed to run on
<whatever> webserver and that webserver may or may not try to use signals in
one way or another. If you're using the CGI SAPI you might be safe, other
than that.... Best of luck to ya.

Well, we do need SIGALRM for timeouts, but yes, beyond that we should be
signal-clean. But as Sara says, PHP is usually embedded inside
something else and that something else tends to use signals for all
sorts of stuff.

-Rasmus