Deadlock on S32-io/IO-Socket-Async.t

gistfile1.txt

$ uname -a
Linux nifftuk.dev 4.6.4-201.fc23.x86_64 #1 SMP Tue Jul 12 11:43:59 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
$ ./perl6 --version
This is Rakudo version 2016.08.1-22-g597052f built on MoarVM version 2016.08-11-gedd5839
implementing Perl 6.c.
$ for i in `seq 1 100`; do ./perl6 t/spec/S32-io/IO-Socket-Async.t ; done
1..7 # hangs :-o
$ ps ax | grep moar 
10834 pts/4    tl+    0:00 /home/bart/usr/bin/moar --execname=./perl6 --libpath=/home/bart/usr/share/nqp/lib --libpath=. /home/bart/Code/rakudo/perl6.moarvm t/spec/S32-io/IO-Socket-Async.t
$ gdb /home/bart/usr/bin/moar 108394
GNU gdb (GDB) Fedora 7.10.1-31.fc23
(gdb) thread apply all where
Thread 3 (Thread 0x7f951b3d9700 (LWP 10862)):
#0  0x00007f951da82b20 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00007f951e5f6c25 in uv_cond_wait (cond=0x40268c0, mutex=0x4026870) at 3rdparty/libuv/src/unix/thread.c:380
#2  0x00007f951e558a43 in shift (tc=0x408e480, st=0x2c8f100, root=0x7f951bc340f0, data=0x7f951bc34108, value=0x34d9df8, kind=8) at src/6model/reprs/ConcBlockingQueue.c:178
#3  0x00007f951e4bd58a in MVM_interp_run (tc=0x408e480, initial_invoke=0x7f951e4e9bb3 <thread_initial_invoke>, invoke_data=0x408e7b0) at src/core/interp.c:2220
#4  0x00007f951e4e9d05 in start_thread (data=0x408e7b0) at src/core/threads.c:77
#5  0x00007f951e5f66b4 in uv__thread_start (arg=0x408e7d0) at 3rdparty/libuv/src/unix/thread.c:49
#6  0x00007f951da7d61a in start_thread () from /lib64/libpthread.so.0
#7  0x00007f951e09859d in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7f9519f79700 (LWP 10863)):
#0  0x00007f951e0927a9 in syscall () from /lib64/libc.so.6
#1  0x00007f951e5e3f9d in uv__epoll_wait (epfd=21, events=0x7f9519f747c0, nevents=1024, timeout=-1) at 3rdparty/libuv/src/unix/linux-syscalls.c:321
#2  0x00007f951e5e0f20 in uv__io_poll (loop=0x3fb9d20, timeout=-1) at 3rdparty/libuv/src/unix/linux-core.c:243
#3  0x00007f951e5e74fe in uv_run (loop=0x3fb9d20, mode=UV_RUN_DEFAULT) at 3rdparty/libuv/src/unix/core.c:351
#4  0x00007f951e514e50 in enter_loop (tc=0x36d1300, callsite=0x7f951ea32020 <null_args_callsite>, args=0x0) at src/io/eventloop.c:63
#5  0x00007f951e534211 in invoke_handler (tc=0x36d1300, invokee=0x7f951bc38020, callsite=0x7f951ea32020 <null_args_callsite>, args=0x0) at src/6model/reprs/MVMCFunction.c:9
#6  0x00007f951e4e9c89 in thread_initial_invoke (tc=0x36d1300, data=0x36d16b0) at src/core/threads.c:56
#7  0x00007f951e4ad06e in MVM_interp_run (tc=0x36d1300, initial_invoke=0x7f951e4e9bb3 <thread_initial_invoke>, invoke_data=0x36d16b0) at src/core/interp.c:61
#8  0x00007f951e4e9d05 in start_thread (data=0x36d16b0) at src/core/threads.c:77
#9  0x00007f951e5f66b4 in uv__thread_start (arg=0x4481b90) at 3rdparty/libuv/src/unix/thread.c:49
#10 0x00007f951da7d61a in start_thread () from /lib64/libpthread.so.0
#11 0x00007f951e09859d in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7f951ec27700 (LWP 10834)):
#0  0x00007f951da82b20 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00007f951e5f6c25 in uv_cond_wait (cond=0x3fd0030, mutex=0x44833c0) at 3rdparty/libuv/src/unix/thread.c:380
#2  0x00007f951e557b93 in MVM_conditionvariable_wait (tc=0x6c47c0, cv=0x7f951bc25070) at src/6model/reprs/ConditionVariable.c:135
#3  0x00007f951e4cb27d in MVM_interp_run (tc=0x6c47c0, initial_invoke=0x7f951e5c98b5 <toplevel_initial_invoke>, invoke_data=0x734848) at src/core/interp.c:4043
#4  0x00007f951e5c99d8 in MVM_vm_run_file (instance=0x6c4010, filename=0x7fff315c9066 "/home/bart/Code/rakudo/perl6.moarvm") at src/moar.c:304
#5  0x00000000004011ef in main (argc=6, argv=0x7fff315c8958) at src/main.c:191