Beefy Boxes and Bandwidth Generously Provided by pair Networks Joe
Don't ask to ask, just ask
 
PerlMonks  

Re: Backticks and SIGALRM

by BrowserUk (Pope)
on Aug 20, 2007 at 15:09 UTC ( #633845=note: print w/ replies, xml ) Need Help??


in reply to Backticks and SIGALRM

T'is easy with a thread:

#! perl -slw use strict; use threads; use threads::shared; $|++; our $N ||= 11; my $TIMEOUT = 10; my $extApp = q[ perl -lwe"$|++; print $_ and sleep 1 for 1 .. $ARGV[0] +" ]; my @results :shared; my $pid :shared; async { $pid = open my $fh, "$extApp $N |" or die "$!, $^E"; @results = <$fh>; }->detach; kill 0, $pid while sleep 1 and $TIMEOUT--; kill 3, $pid and warn 'Command timed out' if $TIMEOUT; print "command return \n'@results'"; __END__ c:\test>junk6 -N=8 command return '1 2 3 4 5 6 7 8 ' c:\test>junk6 -N=10 command return '1 2 3 4 5 6 7 8 9 10 ' c:\test>junk6 -N=12 Command timed out at c:\test\junk6.pl line 21. command return '1 2 3 4 5 6 7 8 9 10 11 '

Wrapping that into a sub is left as an exercise.


Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.


Comment on Re: Backticks and SIGALRM
Download Code
Re^2: Backticks and SIGALRM
by nemo (Sexton) on Aug 20, 2007 at 15:35 UTC
    BrowserUk,
    Thanks for your reply, it's a working solution to the problem. :)
    Many thanks for all replies.

    Nemo

      YW. Here's a slightly cleaner implementation. The only caveat is that it abitrarially throws away any output received prior to the timeout occuring. Only you can decide how you want to signal timeout if you also wish to retrieve any partial output.

      I guess this could form the basis of a whole CPAN module, but it just seems altogether too trivial for that?

      #! perl -slw use strict; $|++; my $extApp = q[ perl -lwe"$|++; print $_ and sleep 1 for 1 .. 10" ]; for my $timeout ( map $_*2, 4,5,6 ) { my @results = timedCommand( $extApp, $timeout ); if( @results ) { print "Command returned\n", join '', @results; } else { print "Command timed out after $timeout seconds"; } } sub timedCommand { use threads; use threads::shared; my( $cmd, $timeout ) = @_; my @results :shared; my $pid :shared; async { $pid = open my $fh, "$cmd |" or die "$!, $^E"; @results = <$fh>; }->detach; kill 0, $pid while sleep 1 and $timeout--; kill 3, $pid and return if $timeout; return @results; } __END__ c:\test>junk6 Command timed out after 8 seconds Command returned 1 2 3 4 5 6 7 8 9 10 Command returned 1 2 3 4 5 6 7 8 9 10

      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
        The only problem I had with your code was the sleep delay was too long. :) The script was executing over tens of thousands of files so in the end I used the implementation below.
        sub executeTimed{ my $cmd = shift; $|++; my @results :shared; my $pid :shared; async { $pid = open my $fh, "$cmd |" or die "$!, $^E"; @results = <$fh>; }->detach; select(undef, undef, undef, 0.08); my $test = kill (0, $pid); if($test){ kill (3, $pid); push(@results, "Function timed out."); } return pop(@results); }
        Thanks again for all replies.
        I was looking to use default active state perl package and was unsure if ipc-run would execute.

        Nemo

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://633845]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others wandering the Monastery: (6)
As of 2014-04-21 13:37 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    April first is:







    Results (495 votes), past polls