It's that comma on line 11.

s{line 11}{line 11i}. Although you'll need Math::Complex for that.

-- 
Human history becomes more and more a race between education and catastrophe. -- HG Wells

Your narrative is conflicting, in that you say the threads are started, then obtain IP's. Later your error message says the "thread failed to start".

FYI - if you need working thread code, it is available here.

Hello, Sorry if you didn't understand but i couldn't show you code at that time. Now i can. First of all i have this variables:

use SNMP;
use Net::MAC;
my $ip_address : shared= "";
my $pool : shared = 0;
my $nthreads = 10; # Number of threads in pool
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Then i have the code to create a pool of threads like this:

 
foreach (1..$nthreads) {
    threads->create(\&getIP);
}
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Then i have a main thread, the main program if you will, that passes, from a list of ip addresses, an ip to each of the threads on the poool. The code is something like this:

foreach $ip (@ip_addresses) {

   $ip_address = $ip;

   if ($pool==0) {
        print "Main thread has no service threads available, yielding\
+n";
        threads->yield until $pool>0;
   }

   print "Main thread has $pool service threads available\n";

   # signal that a new line is ready
   {
     lock $pool;
     cond_signal $pool;
   }

   print "Main thread sent signal, waiting to be signaled\n";

   # wait for whichever thread wakes up to signal us
   {
     lock $ip_address;
     cond_wait $ip_address;
   }

   print "Main thread received signal, reading next line\n";


}
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Then i have my sub for each thread which is something like this:

sub getIP {

  while (1) {

                print "Thread ",$self->tid," waiting\n";
                {
                        lock $pool;
                        $pool++;
                        print "Pool incrementada : $pool\n";
                        cond_wait $pool; #all threads wait here for si
+gnal
                        $pool--;
                        print "Pool decrementadas : $pool \n";
                }

                # Here i get the ip address
                my $t_ip = $ip_address;

                sleep 1;

               # now let's tell main that we already have the ip addre
+ss
                print "Thread ",$self->tid," retrieved data, signaling
+ main\n";
                {
                        lock ($ip_address);
                        cond_signal ($ip_address);
                }

               #now i do the snmp session in the thread plus a snmpget
               my $sess = new SNMP::Session (DestHost => $t_ip, Commun
+ity => ..., Version => '2c', UseSprintValue => '1')
or die "couldn't open a session";

               #The oid
               my $itens = new SNMP::VarList(['sometextthing', $oid]) 
+or die "couldn't create a varlist";
               $info = $sess->get($itens) or die "couldn't get info";
...
}
}
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The threads start ok but when they try to do the snmpget it appears something like "thread failed to start at "line of the get". Couldn't get info" blablabla. I printed every variable that there was to print. I tried testing the snmpget in another script with the same oid and it worked. I don't know if this has anything to do with snmpsession not being thread safe because i create a session inside each thread. Sorry if all of this seems confusing but it's my first post in here. I usually find the solution to my problems by browsing this site. All problems except this one. Also i had to arrange a similar code to exemplify the problem since i can't post here the real code. Cheers.

The "thread failed to start" is a red-herring/badly chosen error message. It simple means that the thread died.

The reason the thread dies is because you are asking it to:

$info = $sess->get($itens) or die "couldn't get info";
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There are many reasons why the get() could fail. The first thing to do is get some more information than your error message gives. Appending $sess->error to your message would be a good start.

If that doesn't help you resolve the problem, try enabling debug:

$session->debug( DEBUG_ALL );
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See the POD for details.

Once you know why that call is failing, you have a chance to do something about it.

---

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.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."