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Re^2: Program Hangs

by anbarasans85 (Initiate)
on Dec 05, 2010 at 04:14 UTC ( #875457=note: print w/ replies, xml ) Need Help??


in reply to Re: Program Hangs
in thread Program Hangs

Hi All, Thanks for the reply. I read the comment about minimum sample code to be presented. But I am posting all here. (I am not able to edit). The comments will be useful in understanding the code.

#!/usr/bin/perl # #Program to calculate end to end delay. # #1. Program reads the trace file, finds for combination of 's' source +event and 'AGT' packet type. #2. For this combination, the program takes the packet id and timestam +p. #3. Within the same file, the program searches for a combination of 'r +' receive event and 'AGT' packet type. #4. For this combination, the program takes the packet id and compares + with previous packet id. If they are same, timestamp is noted. #5. Difference between step 4 timestamp and step 3 timestamp gives the + end to end delay for that packet. #6. Delays are aggregated and average delay is found. # #use strict; use warnings; $SIG{INT} = sub { my (@stack, $level); while(1) { my ($pkg, $fn, $ln, $sub) = caller($level++); if (!($pkg or $fn or $ln or $sub)) { for (my $i = 0; $i < @stack; $i++) { print " " x $i, $stack[$i], "\n"; } exit; } unshift @stack, "-> $pkg: $fn (line $ln) sub $sub"; } }; #Input trace file my($infile) =$ARGV[0]; #Keep track of variables my($enqueue_time) = 0; my($receive_time) = 0; my($packet_id) = 0; my($delay) = 0; my($total_receive_count) = 0; my($sum_of_delay) = 0; my($average_delay) = 0; my($simulation_time) = 0; my($file_position) = 0; my (@x); open(DATA,"<","$infile" ) || die "could't open $infile$!"; while(<DATA>) { @x=split(' '); if(($x[0] eq 's') && ($x[3] eq 'AGT')) { $file_position = tell(DATA); $enqueue_time = $x[1]; $packet_id = $x[5]; while(<DATA>) { ===LINE 58: @x=split(' '); if(($x[0] eq 'r') && ($x[3] eq 'AGT')) { if(($x[5] == $packet_id)) { $receive_time = $x[1]; $total_receive_count++; $delay = $receive_time - $enqueue_time; $sum_of_delay = $sum_of_delay + $delay; #Following is for debug. $delay = $delay * 1000; print("\nDelay:$delay"); last; } } } #Continue to search for next 's' event from where the previous + 's' was found. #So move to the same line where previous 's' event was found. ====LINE 78: seek(DATA,$file_position,SEEK_SET); } #While(<DATA>) takes care of moving to the next line. } $simulation_time = $x[1]; print("\n Simulation Time = $simulation_time seconds"); print("\n Total Receive Count = $total_receive_count"); if($total_receive_count != 0 ) { $average_delay = $sum_of_delay / $total_receive_count; $average_delay = $average_delay * 1000; print("\n Average End to End Delay = $average_delay milliseconds") +; } else { print("\n No packet received."); } print("\n"); print("\n"); close DATA; exit(0);

About the statements like "very quickly" "for some more time"...:
1. When I use a trace file with 800 lines, the script successfully completes without any problem.
2. When I use 80 MB trace file, it hangs. It stops within 12.456 seconds after invoking the script. stops at line 58. main: e2edelay.pl (line 58) sub main::__ANON__
3. When I use 100MB trace file, it hangs. It stops within 1.982 seconds after invoking the script. Stops at line 58. Same stack message.
4. When I use 107 MB trace file, it hangs. It stops within 0.4 seconds after invoking the script. Stops at line 58. Same stack message.

One comment: If the program works for small trace file, why it does not work for larger file?
Using "use strict" command throws error "Bareword "SEEK_SET" not allowed while "strict subs" in use at e2edelay.pl line 78."

I have marked line number in the code: LINE <num>


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Re^3: Program Hangs
by liverpole (Monsignor) on Dec 05, 2010 at 04:28 UTC
    Hi anbarasans85,

    It's not easy to tell without access to your specific data.

    However, one thing that strikes me as dangerous is:

    while(<DATA>) { #... if(($x[0] eq 's') && ($x[3] eq 'AGT')) { $file_position = tell(DATA); #... while(<DATA>) { #... } seek(DATA,$file_position,SEEK_SET); } }

    Which just has "infinite loop" written all over it.  As soon as you're done reading from <DATA>, you jump back to the marked $file_position which you previously saved.

    Try putting a print statement in the outer loop, and see if that isn't the problem.


    s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/
Re^3: Program Hangs
by AnomalousMonk (Abbot) on Dec 05, 2010 at 10:20 UTC
    Using "use strict" command throws error "Bareword "SEEK_SET" not allowed ...

    SEEK_SET is a constant imported from Fcntl (see seek, first paragraph):
        use Fcntl qw(SEEK_SET);
    or
        use Fcntl qw(:seek);

    Import it and restore use strict;

    Update: So, WHENCE are you seeking if SEEK_SET is not defined in your program? My guess is it's the same as using 0, but that's not tested.

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