Re^15: Print inside SIGNALS (updated)

Thank you very much for your reply! As I replied to pryrt, I also now see the different behavior on Windows.

During all my earlier testing I was actually reminded of an interaction between sleep and alarm: "You probably cannot mix alarm and sleep calls, because sleep is often implemented using alarm." Note how the second and third times are the same:

$ perl -wMstrict -e '$SIG{ALRM}=sub{print time." Timeout"};print time.
+" Before\n";alarm 2;sleep 10;print time." After\n"'
1532118865 Before
1532118867 Timeout1532118867 After
[download]

But if you emulate sleep with polling, you see the same buffering issue as in the other cases - here, the second line of output isn't printed until after the 10 seconds are up:

$ perl -wMstrict -e '$SIG{ALRM}=sub{print time." Timeout"};print time.
+" Before\n";alarm 2;$a=time+10;1 while time<$a;print time." After\n"'
1532118963 Before
1532118965 Timeout1532118973 After
[download]

Update: And on Windows:

> perl -wMstrict -e "$SIG{ALRM}=sub{print time.qq{ Timeout}};print tim
+e.qq{ Before\n};alarm 2;sleep 10;print time.qq{ After\n}"
1532119202 Before
1532119204 Timeout1532119212 After

> perl -wMstrict -e "$SIG{ALRM}=sub{print time.qq{ Timeout}};print tim
+e.qq{ Before\n};alarm 2;$a=time+10;1 while time<$a;print time.qq{ Aft
+er\n}"
1532119272 Before
1532119274 Timeout1532119282 After
[download]

Where each second line of output isn't printed until after 10 seconds.

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Re^16: Print inside SIGNALS (updated) by Veltro (Hermit) on Jul 20, 2018 at 21:26 UTC
Ah yes, that explains stuff. On Linux I noticed that the sleep got interrupted and not on Windows I just finished my tests on Windows and I was just about to post the same results Where each second line of output isn't printed until after 10 seconds. Exactly Note: My head is still spinning around the suspended sleep (previous post) I think that the first sleep actually got suspended, I am actually pretty amazed by that, jee, think about it, it must almost be something like a process context switch...	[reply]

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Re^16: Print inside SIGNALS (updated)
by Veltro (Hermit) on Jul 20, 2018 at 21:26 UTC

Ah yes, that explains stuff. On Linux I noticed that the sleep got interrupted and not on Windows

I just finished my tests on Windows and I was just about to post the same results

Where each second line of output isn't printed until after 10 seconds.

Exactly

Note: My head is still spinning around the suspended sleep (previous post) I think that the first sleep actually got suspended, I am actually pretty amazed by that, jee, think about it, it must almost be something like a process context switch...

[reply]