record-child-memory-usage.pl

#!/usr/bin/env perl

use strict;
use warnings;
use autodie;
use feature qw(say);

use Fcntl;
use File::Slurp qw(read_file);

my @command = @ARGV;

open my $fh, '>', '/tmp/mem-usage';
my $pid = fork();

my ( $sentinel_read, $sentinel_write );

pipe $sentinel_read, $sentinel_write;

fcntl($sentinel_write, F_SETFD, FD_CLOEXEC);

if($pid) {
    close $sentinel_write;
    do {
        my $buffer;
        sysread $sentinel_read, $buffer, 1;
    };

    while(1) {
        my @statm = split /\s+/, scalar(read_file("/proc/$pid/statm", chomp => 1));
        last if $statm[1] == 0;
        say {$fh} $statm[1];
        sleep 1;
    }
    waitpid $pid, 0;
} else {
    close $sentinel_read;
    exec @command;
    die "couldn't execute command";
}

close $fh;