in reply to Re^2: System call doesn't work when there is a large amount of data in a hash
in thread System call doesn't work when there is a large amount of data in a hash
Using the memory gobbling technique by Corion here, let's do some testing. I divided by 2 to reflect the actual memory consumption desired.
My virtual CentOS 7 machine has 4 GB of RAM allocated to it. This creates a 3 GB scalar key-value pair to consume 75%. The system command called by the main process fails, no ls output on the 2nd time. Calling syscmd succeeds due to the background worker spun early.
syscmd
use strict; use warnings; use MCE::Child; use MCE::Channel; my $chnl = MCE::Channel->new( impl => 'Simple' ); # spin up worker early before creating big hash mce_child { local $SIG{__WARN__} = sub {}; while ( my ($cmd, @args) = $chnl->recv ) { local ($?, $!); system($cmd, @args); $chnl->send2($?, $!); } }; sub syscmd { my $cmd = shift; return unless $cmd; $chnl->send($cmd, @_); my ($status, $errmsg) = $chnl->recv2; if ($status == -1) { print "SYSTEM: failed to execute ($cmd): $errmsg\n"; } elsif ($status & 127) { printf "SYSTEM: $cmd died with signal %s, %s coredump\n", ($status & 127), ($status & 128) ? 'with' : 'without'; } else { printf "SYSTEM: $cmd exited with status %d\n", $status >> 8; } } # My CentOS VM has 4 GB of RAM # create big hash my $memory_eaten = 3 * 1024*1024*1024 / 2; # 3 GB, adjust to fit my %memory_eater = ( foo => scalar( ' ' x $memory_eaten ), ); # pass command and optionally args syscmd('ls'); # this one works; see status that it succeeded system('ls'); # this one fails; no ls output the 2nd time # attempt to run a command not found syscmd('something'); # sleep for 2 seconds syscmd('sleep', '2'); # busy loop, see top output in another terminal # notice the memory consumption (i.e. RES) # press Ctrl-C to exit or let it finish 1 for 1..3e8; # notify no more work, then reap worker $chnl->end; MCE::Child->waitall;
output:
ls output from syscmd SYSTEM: ls exited with status 0 SYSTEM: failed to execute (something): No such file or directory SYSTEM: sleep exited with status 0
Regards, Mario
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Re^4: System call doesn't work when there is a large amount of data in a hash (testing)
by Nicolasd (Acolyte) on May 01, 2020 at 00:33 UTC | |
Re^4: System call doesn't work when there is a large amount of data in a hash (testing)
by Nicolasd (Acolyte) on Apr 30, 2020 at 00:44 UTC | |
Re^4: System call doesn't work when there is a large amount of data in a hash (testing)
by Nicolasd (Acolyte) on Apr 30, 2020 at 00:19 UTC | |
by marioroy (Prior) on Apr 30, 2020 at 00:43 UTC |
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