From 8c5828c922b5eb6979ceb32e11e32e1abe8c71fd Mon Sep 17 00:00:00 2001
From: Jim Jagielski
The following Mutex types are available:
none
+none | no
This is the default where no Mutex is used at all. Use it at your own risk. But because currently the Mutex is mainly used for synchronizing write access to the SSL Session Cache you can live without it as long as you accept a sometimes garbled Session Cache. So it's not recommended to leave this the default. Instead configure a real Mutex.
file:/path/to/mutex
+posixsem
+ + This is an elegant Mutex variant where a Posix Semaphore is used when possible. + It is only available when the underlying platform + and APR supports it.
sysvsem
+ + This is a somewhat elegant Mutex variant where a SystemV IPC Semaphore is used when + possible. It is possible to "leak" SysV semaphores if processes crash before + the semaphore is removed. It is only available when the underlying platform + and APR supports it.
sem
+ + This directive tells the SSL Module to pick the "best" semaphore implementation + available to it, choosing between Posix and SystemV IPC, in that order. It is only + available when the underlying platform and APR supports at least one of the 2.
pthread
- This is the portable and (under Unix) always provided Mutex variant where
- a physical (lock-)file is used as the Mutex. Always use a local disk
- filesystem for /path/to/mutex
and never a file residing on a
- NFS- or AFS-filesystem. Note: Internally, the Process ID (PID) of the
+ This directive tells the SSL Module to use Posix thread mutexes. It is only available
+ if the underlying platform and APR supports it.
fcntl:/path/to/mutex
+
+ This is a portable Mutex variant where a physical (lock-)file and the fcntl()
+ fucntion are used as the Mutex.
+ Always use a local disk filesystem for /path/to/mutex
and never a file
+ residing on a NFS- or AFS-filesystem. It is only available when the underlying platform
+ and APR supports it. Note: Internally, the Process ID (PID) of the
Apache parent process is automatically appended to
/path/to/mutex
to make it unique, so you don't have to worry
about conflicts yourself. Notice that this type of mutex is not available
under the Win32 environment. There you have to use the semaphore
mutex.
sem
+flock:/path/to/mutex
+
+ This is similar to the fcntl:/path/to/mutex
method with the
+ exception that the flock()
function is used to provide file
+ locking. It is only available when the underlying platform
+ and APR supports it.
file:/path/to/mutex
+
+ This directive tells the SSL Module to pick the "best" file locking implementation
+ available to it, choosing between fcntl
and flock
,
+ in that order. It is only available when the underlying platform and APR supports
+ at least one of the 2.
default | yes
- This is the most elegant but also most non-portable Mutex variant where a - SysV IPC Semaphore (under Unix) and a Windows Mutex (under Win32) is used - when possible. It is only available when the underlying platform - supports it.