php-fpm 没有响应，僵死，求教

xin478

php 5.2.17，用fpm+nginx，运行一段时间后，会出现php没响应的情况，出问题时的fpm日志如下
Aug 22 15:02:33.662270 [WARNING] fpm_request_check_timed_out(), line 146: child 30780, script '/home/php/public_html/interface.php' (pool default) executing too slow (10.093213 sec), logging
Aug 22 15:02:33.676339 [NOTICE] fpm_children_bury(), line 194: child 30780 stopped for tracing
Aug 22 15:02:33.676362 [NOTICE] fpm_php_trace(), line 139: about to trace 30780
Aug 22 15:02:33.676603 [NOTICE] fpm_php_trace(), line 167: finished trace of 30780
Aug 22 15:02:33.677184 [NOTICE] fpm_got_signal(), line 48: received SIGCHLD
Aug 22 15:02:33.807947 [WARNING] fpm_request_check_timed_out(), line 158: child 30780, script '/home/php/public_html/interface.php' (pool default) execution timed out (10.238228 sec), terminating
===============slow.log===============
Aug 22 15:02:33.676418 pid 30780 (pool default)
script_filename = /home/php/public_html/interface.php

Aug 22 15:02:33.676734 pid 30781 (pool default)
script_filename = /home/php/public_html/interface.php

Aug 22 15:02:33.808318 pid 30783 (pool default)
script_filename = /home/php/public_html/interface.php

出问题的时候，连slow里面的堆栈都不打印了，请求能接收，就是没响应，然后nginx超时后就报502了，哪位有遇到过，指点下