Perl - Hash of Arrays across Threads

Question

I’m a beginner in Perl but have to develop some script to parse TCP-dump. Here it is (I truncated it and leave the relevant code only):

I get the following error: Thread 1 terminated abnormally: Invalid value for shared scalar at TestThread1.pl line 16, This is because of this string: %input = (%input, $fix_ClOrdID => [$FrameTime_epoch,$fix_MsgType]);

From many similar topics I’ve read I understand that I cannot share a nested references using threads::shared. And I also found some workaround how to do it. But due to lack of experience I can’t apply examples for my case.

Could you please advise how to fix my script to make it work!

use threads;
use threads::shared;
my %input:shared = ();
threads->new(\&FixParser)->detach();

sub FixParser{  
 open(InFile, 'myFix.dmp') || die;
 while(InFile>){
  ($FrameTime_epoch,$fix_MsgType,$fix_ClOrdID) = split(';',);
  if(exists($input{$fix_ClOrdID})){
   $ExecDelay=$FrameTime_epoch-$input{$fix_ClOrdID}[0];
   print "MsgType: $input{$fix_ClOrdID}[1] ExecDelay: $ExecDelay us\n";
   delete($input{$fix_ClOrdID});
  }
  else{
   %input = (%input, $fix_ClOrdID => [$FrameTime_epoch,$fix_MsgType]);
  }
 }
}

Did you copy/paste the actual code from your application? I can't help but notice you didn't use strict; use warnings;, and the code as listed wouldn't compile. For example, I'm just eyeballing it but this line while(InFile>) should say while(<InFile>). Try adding use strict; use warnings; and fix those errors. If there's still a problem you should ask again. — dms
– dms, Commented Jan 27, 2014 at 8:46

mpapec · Accepted Answer · 2014-01-27 09:05:19Z

1

Lock your shared variable and clone structure before adding to hash,

sub FixParser {  
  open(my $InFile, "<", 'myFix.dmp') || die $!;
  while(<$InFile>) {

    ADVISORY_LOCK: {
      lock(%input);
      # ..
      if(exists($input{$fix_ClOrdID})) {
        # ..
      }
      else{
       # %input = (%input, $fix_ClOrdID => [$FrameTime_epoch,$fix_MsgType]);
       $input{ $fix_ClOrdID } = threads::shared::shared_clone( [$FrameTime_epoch,$fix_MsgType] );
      }
    }

  }
}

answered Jan 27, 2014 at 9:05

mpapec

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1 Comment

user3239496 Over a year ago

Thanks a lot!! It seems working! But this $input{ $fix_ClOrdID } = threads::shared::shared_clone( [$FrameTime_epoch,$fix_MsgType] ); just replaces the last entry of hash but I need to add entries into %input..

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