ajayguptab has asked for the wisdom of the Perl Monks concerning the following question:

Hi All, I have a query on the usage of Open3(). Can somebody tell me how can I make the HIS_OUT to be interactive? 

sub executeJcas(){

    my @clipListFromInputFile = @_;
    
    # Execute the script and generate log and error files
    local(*HIS_IN, *HIS_OUT, *HIS_ERR);
    my $cmd = "export LD_LIBRARY_PATH=$path;$javapath -jar $jcassPath"
+;
    my $childpid = open3(*HIS_IN, *HIS_OUT, *HIS_ERR, $cmd);
    print HIS_IN "po $authenticationString\n";
    if($mode eq "set"){
        foreach $clipId (@clipListFromInputFile){
            print HIS_IN "co $clipId\n";
            print HIS_IN "clipSetRetentionHold true $retentionhold_Id\
+n";
            print HIS_IN "cw\n";
            print HIS_IN "cc\n";
        }    
    }else{
        foreach $clipId (@clipListFromInputFile){
            print HIS_IN "co $clipId\n";
            print HIS_IN "clipSetRetentionHold false $retentionhold_Id
+\n";
            print HIS_IN "cw\n";
            print HIS_IN "cc\n";
        }
    }    
    print HIS_IN "pc\n";
    print HIS_IN "quit\n";
    close(HIS_IN);            # Give end of file to kid.
    my @outlines = <HIS_OUT>;    # Read till EOF.
    my @errlines = <HIS_ERR>;    # XXX: block potential if massive
    close(HIS_OUT);
    close(HIS_ERR);
    waitpid($childpid, 0);
    if ($?) {
        print STDERR "Unable to execute $jcassPath: @errlines";
        return 1;
    }
    return(\@outlines, \@errlines);
    
}

[download]

The above function executes a Jar file which has it's own prompt. I get as many as 4 million clips(lines) as input to the function. I need to execute the jar file and then the "po $authenticationString" only once. But the next lines needs to be executed 4 million times as the input contains those many lines. every time a command is executed the output is stored in HIS_OUT. If I execute the script with 4 million lines as input the HIS_OUT is going to be huge which will not fit into the @outlines array. I need a solution to make the execution interactive inside the for loop. Can somebody help me in this regard? Thanks, -Ajay

Replies are listed 'Best First'.
Re^5: IPC::Open3 woes
by Corion (Patriarch) on May 25, 2010 at 07:04 UTC

    If you want the output earlier, don't read it into memory all at once.

    @outlines = <HIS_OUT>;

    [download]

    will read the output all at once.

    You can try using a while loop:

    while (defined (my $line = <HIS_OUT>)) {
    chomp;
    print "Read: '$line'\n";
};

    [download]
[reply]
[d/l]
[select]

      Thanks Corion, Is there a way to make it interactive to get the contents of HIS_OUT and HIS_ERR after each execution of the while loop?

[reply]

        What do you mean by "make it interactive" ?

[reply]
Re^5: IPC::Open3 woes
by ikegami (Patriarch) on May 25, 2010 at 14:35 UTC
    By using IPC::Run3 or IPC::Run if possible. If not, you'll need some complicated select code or threads.
[reply]
[d/l]

Back to Seekers of Perl Wisdom