Hello,
We are using PERL 5.8 and some multithread functions.
Unfortunately we have stability issues.
Has anyone heard about similar issues and if yes which workaround solutions have been used?
Let me know if you need more information on the issues.
Many Thanks in advance,
JC
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Here is an update of the question:*
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First of all thanks a lot for all the comments you already made.
At last, I can come back with more details and more ...questions.
I aplogise in advance for this long email.
1/ Perl 5.8.2 was built from source, using gcc 2.95.3, on a SUN E420 (Solaris 7) with multithreading support and ithreads options selected.
The following modules were added in order to get the scheduler.pl script to run:

HTML::Tagset
HTML::Parser
URI
LIBWWW
Date::Calc
Tie::DBI
MIME::Lite
DBI * This issues a warning that multithreaded Perl is not suitable for production environments *
DBD:Oracle


So when setting up the script this warning message came up.
Sould we ignore this meesage?
Because on the other hand when looking at the PERL doc on this site http://www.perldoc.com/perl5.8.0/pod/perlthrtut.html#Status
it is said "The ithreads code has been available since Perl 5.6.0, and is considered stable".
Who should we trust?

2/ Here is the error message generated:

"Attempt to free unreferenced scalar: SV 0x12289c at /opt/ActivePerl-5.8.2/lib/site_perl/5.8.2/sun4-solaris-thread-multi/DBI.pm line 626.
Attempt to free unreferenced scalar: SV 0x12289c at /opt/ActivePerl-5.8.2/lib/5.8.2/sun4-solaris-thread-multi/IO/Socket.pm line 46."

3/ I am going to try to generate a report using perl -d as kindly suggested by Zaxo.

4/ When a error happens within the programme the following function is executed:

sub mydie{
kill "SIGTERM", $$; # suicide!
}

Could someone tell me if it means that all the child threads are immediately killed or only the process where the kill function.
If this mydie function is used in the parent process:
- will it free the ressources allocated to the child thread?
- Will it terminated eventually the child thread as well?

5/ The Threads need to write in a table in an Oracle Database.
Even though a DB connection has been opened in the main programme, we need for each Thread to reopen.
Is it a normal behavior?

6/ Looking at the code below do you foresee any likely issue?
The points that concern me are:
- The database connection is never properly closed.
Then database connection should remain pending till Oracle clear them.
- It is possible to go more than 2 times in the main loop.
But the maximum thread is 2 so after two be created what happens?
Does the program hang on the down() method of the do_job function until one is released.
- In the do_job function, the Thread is created and then the method detach() is called.
Will this call be sequential? Isn't there a risk the thread be cleared before the thread process be properly finished?
- It might be possible to have 2 threads running. Suppose one is going in the exception case of the the_job function.
Then what happens there? Is the Kill function killing the current child or everything?
- Supposing the programme runs correctly till the end.
Then when the instruction "$childs->down($maxchilds)" is executed, will the memory used by the Threads be released?

my ($data, $dbh);
my %locks : shared = ();
my $childs = new Thread::Semaphore(2);
my $db; # Database-Hash

# my %results; # Hash for results-db
my %jobs; # additional information

# if marked here, job will not be tryed again today
my %jobs_done : shared = (); 

# associate hash with Database
$db = tiedb();

my $jobs = 0;

while(1){
    # which job to do next?
    my ($id,$time) = get_next_job_Id_And_Frequency(); /* look up into 
+a table */
    last unless $id;
    $jobs++;
    do_job($id, $time);   
}

# cleaning up
$childs->down($maxchilds);
close LOCK or mydie("cant close $lockfile: $!");
unlink $lockfile or mydie("cant delete $lockfile: $!");

sub do_job {
    my ($id, $time) = @_;
    $childs->down();
    my $thread = threads->create(\&the_job, $id, $time);
    $thread->detach();
}

sub the_job {
    lock(%jobs_done);
    $jobs_done{$id} = 1;
    // Some Job is made here
    If Failure then kill "SIGTERM", $$; # suicide!    
    $childs->up(); # increment semaphore

}

sub tiedb{
    my %db;
    tie %db, 'Tie::DBI', { 
    db => $db_source,
      table => $db_table,
      key => 'id',
      user => $db_user,
      password => $db_passwd,
      CLOBBER => 1,
      AUTOCOMMIT => 1,
      # DEBUG => 1,
    };
    # set DATE-format from Database
    my $dbh = tied(%db)->dbh;
    my $handle = $dbh->prepare($db_setdate);
    $handle->execute();
    $handle->finish();
    return \%db;
}
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THANKS!

Edited by Chady -- added code tags.