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pmie_check starts too many pmie processes when /var/log/pcp is a symboli

To: pcp@xxxxxxxxxxx
Subject: pmie_check starts too many pmie processes when /var/log/pcp is a symbolic link
From: Micah Altman <Micah_Altman@xxxxxxxxxxx>
Date: Mon, 26 Nov 2001 00:26:10 -0500 (EST)
Reply-to: Micah_Altman@xxxxxxxxxxx
Sender: owner-pcp@xxxxxxxxxxx
Under RH 6.2 and PCP 2.2.1...

When /var/log/pcp is a symbolic link, pmie_check fails to detect that a
pmie  process exists, even when it already running, and starts another
one. This leads to an accumulation of pmie processes and eventually to
proc-table overflow.

The is a patch for pmie_check that eliminates the problem of pmie_check
failing to detect run. The fix works for our case, but is probably
incorrect -- so please consider it an illustration. The problem seems to
be that the symlink makes $logfile <> $p_logfile when they both, in fact,
refer to the same file.


*** /usr/share/pcp/bin/pmie_check       Sun Aug 12 00:44:16 2001
--- pmie_check  Sun Nov 25 23:50:38 2001
***************
*** 1,4 ****
! #! /bin/sh
  #Tag 0x00010D13
  #
  # Copyright (c) 1998-2000 Silicon Graphics, Inc.  All Rights Reserved.
--- 1,4 ----
! #! /bin/sh 
  #Tag 0x00010D13
  #
  # Copyright (c) 1998-2000 Silicon Graphics, Inc.  All Rights Reserved.
***************
*** 473,479 ****
  NR == 2       { printf "p_logfile=\"%s\"\n", $0; next }
  NR == 3       { printf "p_pmcd_host=\"%s\"\n", $0; next }
        { next }'`
!           if [ "$p_logfile" = $logfile -a "$p_pmcd_host" = "$fqdn" ]
            then
                pid=$p_id
                break
--- 473,481 ----
  NR == 2       { printf "p_logfile=\"%s\"\n", $0; next }
  NR == 3       { printf "p_pmcd_host=\"%s\"\n", $0; next }
        { next }'`
! 
!           ##if [ "$p_logfile" = $logfile -a "$p_pmcd_host" = "$fqdn" ]
!           if [ $logfile -a "$p_pmcd_host" = "$fqdn" ] # fixes problem when 
/var/log/pcp is a symlink , but not sure if it's correct
            then
                pid=$p_id
                break

______________________________________________________________________________
Micah Altman, Ph.D.             Associate Director, Harvard-MIT Data Center
                Director, Virtual Data Center Project, Harvard U. Library
 Research Associate, Center for Basic Research in the Social Science,
        Faculty of Arts & Sciences, Harvard University
micah_altman@xxxxxxxxxxx           http://data.fas.harvard.edu/micah_altman/
"Entia non sunt multiplicanda sine necessitate" - Doctor Invincibilis
                ("Ad indicia spectate." - Micah's corollary)
Disclaimer: This is an unofficial, unsigned, document.  (Copyright 2001)



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