Nginx worker 100% CPU: SIGALRM/rt_sigreturn loop

[Батогов Евгений]

Привет всем.

У нас подвисает nginx worker и потребляет 100% СPU.
stace показывает следующее:
...
rt_sigreturn(0xe)                       = 2
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 165986344
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 1510
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 108
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 5
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 3
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 856814698
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 6
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 4
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 11
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 15
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 7
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 13
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 12
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = 15
...

В чём может быть причина?