Apache 挂了:Invalid argument: couldn't grab the accept mutex

如题，启动一段时间后，进程数减少，最后剩10个左右，并报错:

[emerg] (22)Invalid argument: couldn't grab the accept mutex

以前貌似也没改过什么，没有出过问题。难道是最近访问量大了造成的（httpd 进程数最高 800左右）？

StackOverflow 上有类似问题，另百度找到一些文章，主要有两个方法:

1. MaxRequestsPerChild 参数设置问题;

2. 添加一行 AcceptMutex posixsem

尚未尝试，先来提问，等尝试完了看看能不能解决。
看看有没有遇到过这个问题的人。

参考:

1. Sf搜索结果

2. apache的MaxRequestsPerChild指令设置不合理导致apache崩潰

3. 求助！apache 不停的挂

4. Invalid argument: couldn't grab the accept mutex with apache

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今天又出现这个问题了。。。50天后出现第二次。。。

[Wed Dec 09 10:12:33 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:35 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:35 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:35 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:35 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:36 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:37 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:39 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:41 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:12:56 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:13:04 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Wed Dec 09 10:14:58 2015] [emerg] (22)Invalid argument: couldn't grab the accept mutex