| Subject: | Possible bug on Parallel ForkManager |
| Date: | Mon, 30 Jun 2014 07:38:47 +0000 |
| To: | "bug-Parallel-ForkManager [...] rt.cpan.org" <bug-Parallel-ForkManager [...] rt.cpan.org> |
| From: | <gilles.xiberras [...] orange.com> |
Hello guys,
First of all I want to thank you for this magic library that allows me to use the performances of my hardware the best I can and reduces the processing time of my programs.!
Ok here is my problem ....
I use :
-On Windows 7 Profesionnal
-Active Perl 5.16.3 build 1603
-Parallel Fork Manager 1.06
I've this kind of message : (Program stopped !)
Free to wrong pool 2c49f50 not 3882c0 at c:\perl64\site\lib\Parallel\ForkManager.pm line 513.
My initial PROGRAM :
use strict;
use Parallel::ForkManager;
use warnings;
my $dir_src_data_master_DBM = "../../../DATABASES/MASTER/DBM/";
#open Hash table stored on the Hard disk
my %h_probe_matrix_gxi_original;
dbmopen(%h_probe_matrix_gxi_original, "${dir_src_data_master_DBM}PROBE_MATRIX_GXI", 0444);
my $MAX_PROCESSES = 10; # nb process.
my $pm = Parallel::ForkManager->new ($MAX_PROCESSES);
my $i;
for ($i = 0 ; $i < 100 ; $i++)
{
my $pid = $pm->start and next;
print "Hello\n";
$pm->finish;
}
print "End\n";
Description :
When You open a Hash table that has been stored on your hard drive and if you do not close it before launching the parallel process then you have the error message.
So I suppose that the fact that the Hash table still opened before running the parallel processes is the problem.
How to Solve the issue :
If you want to use this hash table .... You have to do something like that (associate the initial hash table to a new one and close the initial one).
my %h_probe_matrix_gxi;
%h_probe_matrix_gxi = %h_probe_matrix_gxi_original;
dbmclose(%h_probe_matrix_gxi_original);
PERFORMANCE ISSUE :
Loading the hash table as a global var ... degrades the performance drastically.
My Solution :
This does not look fine, as every child will allocate specific memory to load the hash table, however this solves the error message and the performance issue.
use strict;
use Parallel::ForkManager;
use warnings;
my $dir_src_data_master_DBM = "../../../DATABASES/MASTER/DBM/";
my $MAX_PROCESSES = 10 ;
my $pm = Parallel::ForkManager->new ($MAX_PROCESSES);
my $i;
for ($i = 0 ; $i < 100 ; $i++)
{
my $pid = $pm->start and next;
my %h_probe_matrix_gxi_original;
dbmopen(%h_probe_matrix_gxi_original, "${dir_src_data_master_DBM}PROBE_MATRIX_GXI", 0444);
print "Hello\n";
dbmclose(%h_probe_matrix_gxi_original);
$pm->finish;
}
print "End\n";
Do not hesitate to contact me should you require any additional elements.
Best regards Gilles.
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