(gdb) thread apply all bt

Thread 2 (Thread 0x7ffff730e700 (LWP 17814)):
#0  0x00007ffff7bce10c in __lll_lock_wait () from /usr/lib/libpthread.so.0
#1  0x00007ffff7bc8902 in pthread_mutex_lock () from /usr/lib/libpthread.so.0
#2  0x000000000044a9e1 in _D4core4sync5mutex5Mutex51__T9lock_implTC4core4sync9exception13SyncExceptionZ9lock_implMFNeZv ()
#3  0x000000000044a8a9 in core.sync.mutex.Mutex.lock() ()
#4  0x0000000000434ff2 in _d_monitorenter ()
#5  0x0000000000435dba in core.thread.Thread.add(core.thread.Thread.Context*) ()
#6  0x0000000000435a19 in thread_entryPoint ()
#7  0x00007ffff7bc6314 in start_thread () from /usr/lib/libpthread.so.0
#8  0x00007ffff73f73ed in clone () from /usr/lib/libc.so.6

Thread 1 (Thread 0x7ffff7fca780 (LWP 17810)):
#0  0x00007ffff7bcd910 in sem_wait () from /usr/lib/libpthread.so.0
#1  0x000000000044eec8 in core.thread.suspend(core.thread.Thread) ()
#2  0x0000000000449898 in thread_suspendAll ()
#3  0x000000000043fe8a in gc.gc.Gcx.fullcollect() ()
#4  0x000000000043e4bb in gc.gc.GC.fullCollect() ()
#5  0x000000000042de5b in gc_collect ()
#6  0x000000000042cca9 in core.memory.GC.collect() ()
#7  0x000000000042a4b0 in D main ()