Re: Threads and print

[gone2015]

my @threads = map {
    ## create the workers passing the log file handle and semaphore
    threads->create( \&worker, $log, \$logSem,$_*$N, $_*$N + $N -1);
} 0 .. 5; ## 5 threads each processing 100 "files"

...<hem>that's 6 threads, shirly ?

To process $from..$to in $t threads, how about:

my @threads = map{
  threads->create( \&worker, $log, \$logSem, $from + ($_ - 1), $t, $to
+) ;
} 1 .. $t ;

and in the thread:

  my( $log, $semRef, $from, $step, $to ) = @_;
  for (my $file = $from ; $file <= $to ; $file += $step) {
  ......
  } ;

which deals with the number of files not being an exact multiple of the number of threads, and copes with $from..$to range where $from is not zero and $to is included in the range...

[sandy1028]

Can you please tell me how to create single log file per thread and the values are in sequence order.

[cdarke]

'ang about gov'ner, I thought you wanted to have all the threads writing to the same log file? No? OK, then open a new log file in the worker function. Use some unique value passed as a parameter as part of the file name.

[sandy1028]

Hi, Here I used the code for writing into single log file.
But the threads are not printing the "Processesing file" in sequence order and the lines overlap even if I use lock. How can i avoid this?

#! perl -slw
use strict;
use threads;
use threads::shared;

our $from=1;
our $to=400020;
our $t=5;
sub worker {
    my $tid = threads->tid;
   # my( $log, $semRef, $from, $to ) = @_;

  my( $log, $semRef, $from, $step, $to ) = @_;
  for (my $file = $from ; $file <= $to ; $file += $step) {
        lock $$semRef;
 printf $log "The threads is [%2d] Processesing file%3d\n",$tid, $file
+;
        }

}

## A shared variable used as a semaphore for the log file resource
my $logSem :shared;
## Open the log file in the main thread
open my $log, '>', 'myLog' or die $!;

my @threads = map{
  threads->create( \&worker, $log, \$logSem, $from + ($_ - 1), $t, $to
+) ;
} 1 .. $t ;
## Wait till they are done
$_->join for @threads;

## close the log
close $log;

The threads is [ 1] Processesing file16436
The threads is [ 1] Processesing file16441
The threads is [ 1] Processesing file 2] Processesing file2462
The threads is [ 2] Processesing file2467
The threads is [ 2] Processesing file2472

[sandy1028]

In place of print $log ("The threads is $tid Processing file, $file"); How to print the file names of the directory.

#! perl -slw
use strict;
use threads;
use threads::shared;

our $N ||= 100;

our $t=5;
our $from=1;

our $filenames;

sub worker {
    my $tid = threads->tid;
   # my( $log, $semRef, $from, $to ) = @_;
  my( $log, $semRef, $from, $step, $to ) = @_;
  for (my $file = $from ; $file <= $to ; $file += $step) {
        lock $$semRef;
print $log ("The threads is $tid Processing file, $file");
        }

}

## A shared variable used as a semaphore for the log file resource
my $logSem :shared;
## Open the log file in the main thread
open my $log, ">myLog" or die $!;

my @threads = map{
  threads->create( \&worker, $log, \$logSem, $from + ($_ - 1), $t, $to
+) ;
} 1 .. $t ;
## Wait till they are done
$_->join for @threads;

## close the log
close $log;