Re: subprocesses lifecycle

On 2008-08-29 18:58, Eric Pozharski <whynot@xxxxxxxxxxxxxx> wrote:
C.DeRykus <ced@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
*SKIP*

open my $fd, "/some/task & |"
or die...

However, child subprocesses would then need to be foregrounded with
SIGCONT if the parent wants to kill them before exiting.

Backgrounding doesn't work. I meant it doesn't matter.

time perl -wle '
open my $h, q{(sleep 1 ; /bin/echo -en xyz ) & |} or die $!;
print `ps --cols 60 -O ppid t`;
print <$h>;

You are waiting for input here - of course you can read "xyz\n" only
when the client writes it. So here is your 1 second delay. That has
nothing to do with close.

print `ps --cols 60 -O ppid t`;'
[...]
real 0m1.277s
user 0m0.084s
sys 0m0.080s


If you remove print <$h>; the parent will exit immediately, but the
child will continue to run.

% time perl -wle '
open my $h, q{(sleep 1 ; /bin/echo -en xyz )& |} or die $!;
print `ps --cols 60 -O ppid t`;'
ps --cols 60 -O ppid t
PID PPID S TTY TIME COMMAND
2287 27943 R pts/3 00:00:00 perl -wle ?open my $h, q{(sl
2288 2287 Z pts/3 00:00:00 [sh] <defunct>
2289 2287 R pts/3 00:00:00 ps --cols 60 -O ppid t
2290 1 S pts/3 00:00:00 sh -c (sleep 1 ; /bin/echo -
2291 2290 S pts/3 00:00:00 sleep 1
27943 27942 S pts/3 00:00:00 zsh

perl -wle 0.00s user 0.01s system 71% cpu 0.011 total
PID PPID S TTY TIME COMMAND
2290 1 S pts/3 00:00:00 sh -c (sleep 1 ; /bin/echo -
2291 2290 S pts/3 00:00:00 sleep 1
2292 27943 R pts/3 00:00:00 ps --cols 60 -O ppid t
27943 27942 S pts/3 00:00:00 zsh

hp
.

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