[WARNING] fpm_children_bury(), line 215: child 2736 (pool default) exited on signal 15 SIGTERM after 59.588363 seconds from star

web服务器运行了几个月的时间，PHP的日志文件已经有几百M的大小，打开一看，结果基本全部都是一下的错误

Jun 28 18:17:26.991893 [NOTICE] fpm_children_bury(), line 215: child 20529 (pool default) exited with code 0 after 620.989955 seconds from start
Jun 28 18:17:26.993277 [NOTICE] fpm_children_make(), line 352: child 20903 (pool default) started
Jun 28 18:17:27.130828 [NOTICE] fpm_got_signal(), line 48: received SIGCHLD
Jun 28 18:17:27.130917 [NOTICE] fpm_children_bury(), line 215: child 20516 (pool default) exited with code 0 after 621.136287 seconds from start
Jun 28 18:17:27.132367 [NOTICE] fpm_children_make(), line 352: child 20904 (pool default) started
Jun 28 18:17:27.382621 [NOTICE] fpm_got_signal(), line 48: received SIGCHLD
Jun 28 18:17:27.382714 [NOTICE] fpm_children_bury(), line 215: child 20589 (pool default) exited with code 0 after 621.343461 seconds from start
Jun 28 18:17:27.383791 [NOTICE] fpm_children_make(), line 352: child 20905 (pool default) started
Jun 28 18:17:27.400719 [NOTICE] fpm_got_signal(), line 48: received SIGCHLD
Jun 28 18:17:27.400824 [NOTICE] fpm_children_bury(), line 215: child 20446 (pool default) exited with code 0 after 621.445940 seconds from start
Jun 28 18:17:27.401387 [NOTICE] fpm_children_make(), line 352: child 20906 (pool default) started
Jun 28 18:17:27.470649 [NOTICE] fpm_got_signal(), line 48: received SIGCHLD
Jun 28 18:17:27.470757 [NOTICE] fpm_children_bury(), line 215: child 20579 (pool default) exited with code 0 after 621.438139 seconds from start
Jun 28 18:17:27.471236 [NOTICE] fpm_children_make(), line 352: child 20907 (pool default) started
Jun 28 18:17:28.075124 [NOTICE] fpm_got_signal(), line 48: received SIGCHLD
Jun 28 18:17:28.075217 [NOTICE] fpm_children_bury(), line 215: child 20586 (pool default) exited with code 0 after 622.037538 seconds from start
Jun 28 18:17:28.075799 [NOTICE] fpm_children_make(), line 352: child 20908 (pool default) started
Jun 28 18:17:28.358578 [NOTICE] fpm_got_signal(), line 48: received SIGCHLD

查过网上的资源，基本都是认为是php线程打开文件句柄受限导致的错误。具体的解决的办法如下：

1 提升服务器的文件句柄打开打开

/etc/security/limits.conf : (增加)
*    soft    nofile    51200
*    hard    nofile    51200

2. 提升nginx的进程文件打开数

nginx.conf : worker_rlimit_nofile 51200;

3. 修改php-fpm.conf文件，主要需要修改2处。

<value name="max_requests">10240</value>

<value name="rlimit_files">51200</value>

完成以上修改，警告信息即可避免。