nginx被卡在里这里？check模块的问题么？

[fankeke]

#0 0x00007f1a73c46930 in sem_wait () from /lib64/libpthread.so.0
#1 0x000000000042749c in ngx_shmtx_lock ()
#2 0x00000000004b08e2 in ngx_http_upstream_check_begin_handler ()
#3 0x0000000000433f82 in ngx_event_expire_timers ()
#4 0x0000000000433df8 in ngx_process_events_and_timers ()
#5 0x000000000043c078 in ngx_worker_process_cycle ()
#6 0x0000000000439505 in ngx_spawn_process ()
#7 0x000000000043cb8a in ngx_master_process_cycle ()
#8 0x000000000041c5d4 in main ()

上面是pstack 的输出，nginx不知道什么原因被陷入了这里不再服务了。大家有啥建议么？

[gfrankliu]

问题可重复吗？nginx版本是多少？