Your first regex and Hash usage may be a challange, so here is a complete program, based on a log that looks like this: 
2012-06-01 16:04:46,395 <a href="?node=Thread-12796%20-%20Dispatcher%2
+0thread%20%231">Thread-12796 - Dispatcher thread #1</a> INFO  JMaster
+Protocol  - JMasterProtocol.getMasterPushExitInstance: Asked exit ins
+tance for target 'SPF293R' from dispatcher

[download]
use strict;
use warnings;
use diagnostics;

my $searchfor = shift @ARGV or die "Please specify the search target a
+s an argument";
my (%TargetList, $linecount, @foundThreads);
my $logName = 'test-logfile.txt';

open my $logIn, '<', $logName or die "Can't open $logName: $!\n";

while (defined (my $line = <$logIn>)) {
  $linecount++;
  my ($thread, $target) =  $line=~m/Thread-(\d+).+target\s*'([^']+)'/ 
+or next;
  push @{ $TargetList{$thread}  }, $target;
  if ($target eq $searchfor){
    push @foundThreads, $thread;
  }
}
close $logIn;

if (scalar(@foundThreads)>0){
  print "Target '$searchfor' is in threads " .
            join(",",@foundThreads), "\n";
  print "Targets in these threads are:\n";
  for my $t(sort @foundThreads){
     print "  $t: $_\n" for @{$TargetList{$t}};
  }

}else{
  print "*** Target '$searchfor' was not found in log $logName\n";
}

print "Totals: $linecount lines, ",scalar(keys %TargetList)," Threads.
+\n";

[download]
UpdateRe-read the specifications, and now display context is slightly different.

             I hope life isn't a big joke, because I don't get it.
                   -SNL

In reply to Re: Parsing a logfile. by NetWallah
in thread Parsing a logfile. by concept

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