Proc::ProcessTable::Process returning negative rss?

jimsearle has asked for the wisdom of the Perl Monks concerning the following question:

I have a process using about 11g as reported by ps:

  PID USER        SZ       RSS      COMMAND
 6548 someuser    12339104 12210376 someprocess

But when I use Proc::ProcessTable::Process it returns a big negative number for rss.

          bless( {
                   'cmajflt' => 0,
                   'cminflt' => 18193,
                   'cmndline' => '/tools/atoptech/AP_09.02.rel.5.1/Lin
+ux/bin/rhel4-64/AP -4 -batch scripts/apPNR/droute_opt.scr -wait -tmp_
+dir APTempDir/droute_opt.tmp -adc_dir APTempDir/droute_opt.adc -cmd_l
+og APTempDir/droute_opt.cmd.log -log logs/apPNR/droute_opt.log ',
                   'cstime' => '120000',
                   'ctime' => '320000',
                   'cutime' => '200000',
                   'cwd' => undef,
                   'egid' => 20,
                   'euid' => 9331,
                   'exec' => undef,
                   'fgid' => 20,
                   'flags' => 0,
                   'fname' => 'AP',
                   'fuid' => 9331,
                   'gid' => 20,
                   'majflt' => 12,
                   'minflt' => 3062104,
                   'pctcpu' => '135.55',
                   'pctmem' => '344.00',
                   'pgrp' => 4725,
                   'pid' => 6548,
                   'ppid' => 6541,
                   'priority' => 0,
                   'rss' => -381493248,
                   'sess' => 3879,
                   'sgid' => 20,
                   'size' => 4102443008,
                   'start' => '1260511632',
                   'state' => 'run',
                   'stime' => '547210000',
                   'suid' => 9331,
                   'time' => '53885980000',
                   'ttydev' => '',
                   'ttynum' => 0,
                   'uid' => 9331,
                   'utime' => '53338770000',
                   'wchan' => -1
                 }, 'Proc::ProcessTable::Process' ),
[download]

Is this a bug, or some kind of overflow? I'm going to look at the Process code and try to figure it out, but thought I'd ask here as well. Thanks, Jim

Comment on Proc::ProcessTable::Process returning negative rss? Download Code

Replies are listed 'Best First'.
Re: Proc::ProcessTable::Process returning negative rss? by dwm042 (Priest) on Dec 11, 2009 at 20:47 UTC
Offhand, and without looking at the code, I'd suspect a twos complement overflow. David.	[reply]
Re^2: Proc::ProcessTable::Process returning negative rss? by jimsearle (Initiate) on Dec 12, 2009 at 17:36 UTC
David, Thanks. After further investigation in the XS extension, I see this in `func bless_into_proc ... case 'l': /* long */ l_val = va_arg(args, long); hv_store(myhash, key, strlen(key), newSVnv(l_val), 0);` [download] Which stores the rss (long) as numeric (float) with implicit casting, so it is still a bit of mystery why negative value shows up? - Jim	[reply] [d/l]