I see you earlier asked in #win32. In your script

    use strict;
    use warnings;
    use threads;
    use IO::Socket::INET;
     
    my $s = IO::Socket::INET->new(PeerAddr => 'localhost',
                                  PeerPort => 80,
                                  Proto => 'tcp') or die "error: $@";
     
    print "create t1\n";
     
    my $t1 = threads->create(sub {
            my ($r) = @_;
            my $data = '';
     
            print "in t1\n";
     
            # this intentionally blocks. if this line is removed the p
+roblem vanishes
            $r->recv($data, 64);
     
            print "recv done\n";
    }, $s);
     
    print "create t2\n";
     
    my $t2 = threads->create(sub {
            print "in t2\n"; # problem: this is never printed
    }, 0);
     
    print "done\n"; # problem: this is never printed, as threads->crea
+te never returns
     
    $t1->join();
    $t2->join();
[download]

Your code freezes like this.

Parent thread.

     ntdll.dll!_KiFastSystemCallRet@0()     
     ntdll.dll!_NtQueryVolumeInformationFile@20()  + 0xc    
     kernel32.dll!_GetFileType@4()  + 0x72    
>    msvcr71.dll!_fstati64(int fildes=3, _stati64 * buf=0x0012fab4)  L
+ine 97 + 0x8    C
     perl519.dll!PerlLIOFileStat(IPerlLIO * piPerl=0x00cdc134, int han
+dle=3, _stati64 * buffer=0x0012fab4)  Line 971 + 0xe    C
     perl519.dll!PerlIOUnix_setfd(interpreter * my_perl=0x00000400, _P
+erlIO * * f=0x0012f9cc, int fd=1029, int imode=0)  Line 2571 + 0x15  
+  C
     perl519.dll!PerlIOUnix_dup(interpreter * my_perl=0x00b4b014, _Per
+lIO * * f=0x00b4bac4, _PerlIO * * o=0x00905b24, clone_params * param=
+0x0012fb9c, int flags=1)  Line 2696 + 0xf    C
     perl519.dll!PerlIOBase_dup(interpreter * my_perl=0x00b4b014, _Per
+lIO * * f=0x00b4bac4, _PerlIO * * o=0x008f5574, clone_params * param=
+0x0012fb9c, int flags=1)  Line 2221    C
     perl519.dll!PerlIO_fdupopen(interpreter * my_perl=0x0012f9cc, _Pe
+rlIO * * f=0x00070023, clone_params * param=0x0012fb9c, int flags=1) 
+ Line 503 + 0x13    C
     perl519.dll!Perl_fp_dup(interpreter * my_perl=0x00b4b014, _PerlIO
+ * * const fp=0x008f5574, const char type=0, clone_params * const par
+am=0x0012fb9c)  Line 11825 + 0xb    C
     perl519.dll!PerlIO_clone(interpreter * my_perl=0x0000006c, interp
+reter * proto=0x00000400, clone_params * param=0x0012fb9c)  Line 617 
++ 0xc    C
     perl519.dll!perl_clone_using(interpreter * proto_perl=0x0036471c,
+ unsigned long flags=6, IPerlMem * ipM=0x00000000, IPerlMem * ipMS=0x
+00cdc028, IPerlMem * ipMP=0x00cdc044, IPerlEnv * ipE=0x00cdc060, IPer
+lStdIO * ipStd=0x00cdc098, IPerlLIO * ipLIO=0x00cdc134, IPerlDir * ip
+D=0x00cdc19c, IPerlSock * ipS=0x00cdc1c8, IPerlProc * ipP=0x00cdc278)
+  Line 13649    C
     perl519.dll!perl_clone_host(interpreter * proto_perl=0x0036471c, 
+unsigned long flags=6)  Line 360    C
     threads.dll!S_ithread_create(interpreter * parent_perl=0x00000400
+, sv * init_function=0x008fcc14, long stack_size=0, int gimme=2, int 
+exit_opt=0, int params_start=3, int num_params=1)  Line 794    C
     threads.dll!XS_threads_create(interpreter * my_perl=0x00000002, c
+v * cv=0x0096de44)  Line 1100 + 0x30    C
     perl519.dll!Perl_pp_entersub(interpreter * my_perl=0x00000000)  L
+ine 2794    C
     perl519.dll!Perl_runops_standard(interpreter * my_perl=0x0036471c
+)  Line 42 + 0x4    C
     perl519.dll!S_run_body(interpreter * my_perl=0x0000006c, long old
+scope=1)  Line 2449 + 0xa    C
     perl519.dll!perl_run(interpreter * my_perl=0x0036471c)  Line 2365
+ + 0x8    C
     perl519.dll!RunPerl(int argc=2, char * * argv=0x01362478, char * 
+* env=0x00362d80)  Line 259 + 0x6    C
     perl.exe!mainCRTStartup()  Line 398 + 0xe    C
     kernel32.dll!_BaseProcessStart@4()  + 0x23
[download]

Child thread

     ntdll.dll!_KiFastSystemCallRet@0()     
     ntdll.dll!_ZwDeviceIoControlFile@40()  + 0xc    
     mswsock.dll!_WSPRecv@36()  + 0xd1    
     mswsock.dll!_WSPRecvFrom@44()  + 0xe099    
     ws2_32.dll!_recvfrom@24()  + 0x87    
>    perl519.dll!win32_recvfrom(unsigned int s=3, char * buf=0x00b376f
+4, int len=64, int flags=0, sockaddr * from=0x0117fa10, int * fromlen
+=0x0117fe50)  Line 481 + 0x34    C
     perl519.dll!PerlSockRecvfrom(IPerlSock * piPerl=0x00aad5e0, unsig
+ned int s=3, char * buffer=0x00b376f4, int len=64, int flags=0, socka
+ddr * from=0x0117fa10, int * fromlen=0x0117fe50)  Line 1389 + 0x17   
+ C
     perl519.dll!Perl_pp_sysread(interpreter * my_perl=0x00000400)  Li
+ne 1699    C
     perl519.dll!Perl_runops_standard(interpreter * my_perl=0x0090865c
+)  Line 42 + 0x4    C
     perl519.dll!Perl_call_sv(interpreter * my_perl=0x00158018, sv * s
+v=0x003b92b0, volatile long flags=18348252)  Line 2764 + 0xc    C
     threads.dll!S_ithread_run(void * arg=0x00905c24)  Line 520 + 0x14
+    C
     kernel32.dll!_BaseThreadStart@8()  + 0x37
[download]

Using Process Explorer, which can give a kernel side stack dump (but its HIGHLY INACCURATE since I've never figured out how to make Proc Exp use symbol files).

ntoskrnl.exe!ZwAlertThread+0x28
ntoskrnl.exe!SeAssignSecurityEx+0x13f
ntoskrnl.exe!MmGrowKernelStack+0x61a
ntoskrnl.exe!IoPageRead+0xaf0
ntoskrnl.exe!MmGrowKernelStack+0x659
ntoskrnl.exe!RtlGenerate8dot3Name+0x1ca
ntoskrnl.exe!IoCheckFunctionAccess+0xf841
ntoskrnl.exe!ZwSetSystemInformation+0x23
ntdll.dll!KiFastSystemCallRet
MSVCR71.dll!fstati64+0x63
perl519.dll!win32_stderr+0x302
perl519.dll!PerlIO_teardown+0x3ea
perl519.dll!PerlIOBase_dup+0x33
perl519.dll!PerlIO_allocate+0x8b
perl519.dll!Perl_fp_dup+0x32
perl519.dll!perl_clone_using+0x74f
perl519.dll!perl_clone_host+0x6f
threads.dll+0x2647
[download]

IDK why a GetFileType on a socket while its doing a recv in another thread blocks the GetFileType. If I kill the child OS thread doing the recv (and therefore the ithread with it), the GetFileType/NtQueryVolumeInformationFile unblocks and execution in the parent thread continues.