我们的mongodb在制作中多次挂起，在我看来有一个僵局。
使用gdb，我们可以看到大多数线程都挂在pthread_cond_timedwait。
有没有办法找出哪个线程持有锁？
(gdb) bt full
#0 pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
No locals.
#1 0x0000000000bba269 in mongo::CondVarLockGrantNotification::wait(unsigned int) ()
No symbol table info available.
#2 0x0000000000bbdd37 in mongo::LockerImpl<false>::lockComplete(mongo::ResourceId, mongo::LockMode, unsigned int, bool) ()
No symbol table info available.
#3 0x0000000000bb3ff9 in mongo::Lock::ResourceLock::lock(mongo::LockMode) ()
(gdb) info args
No symbol table info available.
(gdb) info locals
No locals.
(gdb) info registers
rax 0xfffffffffffffdfc -516
rbx 0x7fb988055700 140434827728640
rcx 0xffffffffffffffff -1
rdx 0x35a49 219721
rsi 0x189 393
rdi 0x636d752d4 26689884884
rbp 0x0 0x0
rsp 0x7fb988054a40 0x7fb988054a40
r8 0x636d752a8 26689884840
r9 0xffffffff 4294967295
r10 0x7fb988052990 140434827717008
r11 0x206 518
r12 0x0 0
r13 0x7fb9c9728060 140435925401696
r14 0xb9b0 47536
r15 0x7fb988055700 140434827728640
rip 0x7fb9c80a787d 0x7fb9c80a787d <clone+109>
eflags 0x206 [ PF IF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0