[ This was meant as a reply to Re: How I'm sure syswrite has finished? ]

if the parent is doing something after the for loop to cause the ssh processes to terminate.

I think it's simpler than that. When the parent exits, doesn't that kill the children? Calling wait_all_children is still the solution as that would make sure the children are done.

Many thanks ikegami,

I tried wait_all_children (see answer below) but without success.

Somehow the $pm->finish (I also tried a plain exit) with the same result aborts the whole writing?.

I guess that somehow the call to syswrite produces a decoupled process in the remote machine than is in charge of fulfilling the writing (since it is a huge message). When the exit of the forked local child occurs the remote process is aborted?

I think your issue is that the open of ssh on the local end is also a fork. I'm guessing that maybe close isn't waiting for the child to finish when using open2 the way it does for open. perlipc says open does but doesn't mention this regarding open2. I would wait for the ssh processes to finish before calling $pm->finish. See the waitpid function as well as perlipc.

153 foreach (@str_handles) {
154   my $pid = $pm->start and next;
155
156   $b = syswrite $_->{handle},
157            join(" ",
158                   $_->{chunksize},
159                   $_->{A_cols},
160                   @A_lines[$_->{start}.. $_->{end}],
161                   @B_lines,
162                   "\cN"
163                );
164   # Wait until the writing has finished
165   #sleep(1);
166   $pm->finish;
167 }
168 $pm->wait_all_children;
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Only the sleep seems to work.

My guess is that

$pm->finish;
[download]

I think you need to show us more of your program - especially the part wher eyou create the ssh connections.

Also, the output of strace or truss would help.