Apache shutdown - Couldn't grab mutex

Question

For some reasons unknow to me, Apache is crashing.

This is the apache log at the moment of the crash:

[Sat Jun 02 02:38:05.196006 2018] [mpm_prefork:         


        

Answer 1

I was experiencing the same error on Ubuntu 17.10 with Apache 2.4.27.

It appears to have to do with Apache talking to the OS about file locking. When I went into /etc/apache2/apache2.conf and added Mutex flock to the Mutex section (near the ServerRoot section), it seems to have solved the problem.

Unfortunately, all I can say is that this uses the flock() function (a system call?) to handle file locking. Per https://httpd.apache.org/docs/2.4/mod/core.html#mutex

So it's a bit of a black magic fix in that I personally am not familiar enough with Apache's file locking behavior to say why it works, and I can only say it works because the Apache crash seems to have stopped, but only thus far. Nevertheless, it may help you and seems fairly low-risk.