Re: Perl syntax for enforcing time limits

Very useful!

I have a suggestion: I would mention in the PODs that the sigalrm is used to establish the timeout. Almost every module that has a timeout uses a sigalrm to accomplish the task, and when they're used in combination, strange things happen. (Usually, the last assignment to $SIG{ALRM} overriders any former assignments.)

This would pose problems to those who use Net::Ping, for example, and less seasoned coders may not be aware of what is happening.

I'm going to keep this in my toolkit. I think it will see good use.

Comment on Re: Perl syntax for enforcing time limits

Replies are listed 'Best First'.
Re: Re: Perl syntax for enforcing time limits by ncw (Friar) on Apr 22, 2001 at 05:08 UTC
Glad you like it! Yes I should make the fact that it uses $SIG{ALRM} explicit in the documentation. However note that TimeLimit always uses local $SIG{ALRM} which means that it gets reset to its previous value when it goes out of scope. The answer to Net::Ping of course is that it should use TimeLimit too if it uses alarm(), or if you have some code that you think might be using alarm() &or $SIG{ALRM} and not resetting it then bracket it in a time_limit { } block and that will reset the alarm() & $SIG{ALRM} properly. Ideally I should submit TimeLimit so CPAN so everyone who uses alarm() anywhere should use it instead!	[reply]

Replies are listed 'Best First'.

Re: Re: Perl syntax for enforcing time limits
by ncw (Friar) on Apr 22, 2001 at 05:08 UTC

Yes I should make the fact that it uses $SIG{ALRM} explicit in the documentation. However note that TimeLimit always uses local $SIG{ALRM} which means that it gets reset to its previous value when it goes out of scope.

The answer to Net::Ping of course is that it should use TimeLimit too if it uses alarm(), or if you have some code that you think might be using alarm() &or $SIG{ALRM} and not resetting it then bracket it in a time_limit { } block and that will reset the alarm() & $SIG{ALRM} properly.

Ideally I should submit TimeLimit so CPAN so everyone who uses alarm() anywhere should use it instead!

[reply]