Hi!

I have a problem with using threads and sockets on Windows: threads->create() blocks. The following code is a simplified part of a bigger project in which I found this problem:

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

my $s = IO::Socket::INET->new(PeerAddr => 'www.google.com',
                              PeerPort => 80,
                              Proto => 'tcp') or die "error: $@";

print "create t1\n";

my $t1 = threads->create(sub {
    my ($r) = @_;
    my $data = '';

    print "in t1\n";

    while (1) {
        $r->recv($data, 64);
        #print ">>> $data\n";
    }
}, $s);

# give t1 a moment to execute and to block in the recv call
print "sleep 3s\n";
sleep(3);
print "sleep done\n";

print "create t2\n";

my $t2 = threads->create(sub {
    # problem: this is never printed
    print "in t2\n";

    $s->send("GET / HTTP/1.1\r\n\r\n");
}, 0);

# problem: this is never printed, as threads->create never returns
print "done\n";

$t1->join();
$t2->join();
[download]

The code opens a socket to www.google.com. Google is just used for demonstration purpose. The actual project connects to a special server using a simple request/response protocol. Then thread t1 is created to receive all incoming data. After that I injected a sleep(3) to ensure that t1 is blocking in the recv() call before going on. This is important, the problem of threads->create() hanging only occurs if t1 is blocking in recv(). Finally t2 is created and should send a request. But this never happens on Windows, because threads->create() for t2 never returns.

This problem only occurs on Windows (tested with Strawberry and Active Perl 5.18.2). It doesn't occur on Linux, there this just works as expected.

Am I doing something wrong here? Is there some general problem with this approach that could explain the problem? Or is this a bug in perl itself?

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