Re: Threaded UDP Communication

If you create the socket on the "main" thread and then when creating the "child" threads you pass the socket object as parameter it works as expected as sockets survive thread cloning.
You don't even need shared variables for this to work:

use warnings;
use strict;
use threads;
use IO::Socket;

my $socket = IO::Socket::INET->new(); # pass your parameters

threads->create(\&do_stuff, $socket);

sleep(0xffffffff); # ;-)

sub do_stuff {
  my ($socket) = @_;
  # play happily ever after with $socket in your new thread
}
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Note that this is code is untested, but I'm sure it works because I've got production code like this at work. Actually, it's slightly different, the thread creation doesn't use the "standard parameter passing procedure", so although I can't guarantee the above will work, I'm completely sure that this works:

threads->create(sub { do_stuff($socket) });
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But I guess it should work both ways.

acid06
perl -e "print pack('h*', 16369646), scalar reverse $="

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Re^2: Threaded UDP Communication by valhalla418 (Novice) on Feb 17, 2006 at 13:36 UTC
Thank you, this seems to work perfectly. I guess I was trying to be too clever! However, I've now come across another problem. I need the call to socket->recv to be non-blocking. I see that there is a flags parameter and I'm wondering whether I need to set a flag to make the recv call return immediately but I can't find any documentation for the flags, all I can find it a very old post 129590 which doesn't really help a lot. I've added my code so you can see what I'm trying to do but it's in no way finish yet hence all the print's to help me find out whats going on. Read more... Here's my code (4 kB)	[reply] [d/l]
Re^3: Threaded UDP Communication by valhalla418 (Novice) on Feb 17, 2006 at 15:41 UTC
I've just found a solution to my own problem... I'm quite new to perl and I've just discovered IO:Select after looking at 133389, which solves all my problems! Thanks!	[reply]
Re^2: Threaded UDP Communication by BrowserUk (Patriarch) on Feb 25, 2006 at 09:05 UTC
If you create the socket on the "main" thread and then when creating the "child" threads you pass the socket object as parameter it works as expected as sockets survive thread cloning. You don't even need shared variables for this to work As you point out, you can only get away with this if the filehandle/socket exists prior to creating the thread that will subsequently use it. Which means that everything created in the spawning thread gets cloned into the new thread. Then the next time you spawn a thread, everything that has been created since spawning the previous thread, plus all the stuff created prior to spawning it, get cloned into the new thread. And so on ad nausuem. So each thread you spawn, the time spent cloning gets longer and the memory taken by the thread gets bigger. And as is easily demonstrated, a large proportion of what gets cloned is never recovered when the thread dies. So, each thread created costs more and more in memory (most of which it has no interest in and can never use), and when it dies, it leaves ever bigger chunks of ram behind unusable and unrecoverable. This style of coding, and the reliance upon everything in the parent thread being cloned into the child just so that it may gain access to the one thing it actually needs chews memory like it was an all-you-can-eat buffet. And only being able to pass handles to threads if they were created prior to thread spawning prevents the whole class of solutions that use thread pools. Almost all the problems that dog iThreads exist "by design". The only thing preventing iThreads being fixed and finally made properly useful is the inane, dogged adherance to the 'fork model' of operation. And, if my opinion on this is so wrong, where are all the 'experts' showing us all how it should be done? Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal? "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]