Re^3: Print inside SIGNALS

in reply to Re^2: Print inside SIGNALS
in thread Print inside SIGNALS

I'm on a Debian box as well, and the behaviour is like this:

Your original code doesn't print anything because the program finishes before the timer rings. That's quite normal.
With Corion's example, I get the print - but not the full sleep time, the code immediately resumes after the alarm. I didn't know that, but the alarm documentation gives a hint: It is usually a mistake to intermix "alarm" and "sleep" calls, because "sleep" may be internally implemented on your system with "alarm".

If your C library's print function isn't re-entrant (many aren't), then there's always a chance that weird things happen when the signal goes off while your code is printing something.

Comment on Re^3: Print inside SIGNALS

Replies are listed 'Best First'.
Re^4: Print inside SIGNALS by ikegami (Patriarch) on Jul 16, 2018 at 14:21 UTC
If your C library's print function isn't re-entrant (many aren't), then there's always a chance that weird things happen when the signal goes off while your code is printing something. That's not true for two reasons: `print` doesn't use clib. Since Perl 5.8.1, signals are deferred to be handled between Perl ops.	[reply] [d/l]
Re^5: Print inside SIGNALS by haj (Vicar) on Jul 16, 2018 at 14:41 UTC
Thanks for the correction! The rule "don't print in signal handling" stuck with me for too long, I should have checked this.	[reply]

In Section Seekers of Perl Wisdom