apache 服务启动失败，信号量未释放
1. apache故障现象
因为之前一直用reload热部署apache，可能有些mutex信号量没有释放，造成无法申请。有时会导致apache 启动/加载失败，并且报一些如下的错误 -->
[Mon Jul 04 14:13:59.260922 2016] [core:emerg] [pid 27103] (28)No space left on device: AH00023: Couldn\'t create the rewrite-map mutex
[Mon Jul 04 14:13:59.260946 2016] [:emerg] [pid 27103] AH00020: Configuration Failed, exiting
2. 解决办法
则执行下面语句，释放同步信号量
ipcs | grep apache | awk \'{print $2}\' > signal.txt
for i in `cat signal.txt` ; do { ipcrm -s $i; } ; done;
3. 再次重启apache即可解决