From: Luca Toscano AsyncRequestWorkerFactor
.
MaxRequestWorkers
/ ThreadsPerChild
), meanwhile
- the Scoreboad is a representation of all the running processes and
+ the Scoreboard is a representation of all the running processes and
the status of their worker threads. If the scoreboard is full (so all the
threads have a state that is not idle) but the number of active requests
served is not MaxRequestWorkers
,
@@ -158,17 +158,24 @@ of the AsyncRequestWorkerFactor
.
but that are queued instead (up to the limit imposed by
ListenBacklog
). Most of the times
the threads are stuck in the Graceful state, namely they are waiting to
- finish their work with a TCP connection to terminate and free a
+ finish their work with a TCP connection to safely terminate and free up a
scoreboard slot (for example handling long running requests, slow clients
- or a connection with keep-alive enabled). Two scenarios are very common:
+ or connections with keep-alive enabled). Two scenarios are very common:
MaxSpareThreads
).
This is particularly problematic because when the load increases again,
- httpd will try to start more processes.
- If the pattern repeats, the number of processes can rise quite a bit.
+ httpd will try to start new processes.
+ If the pattern repeats, the number of processes can rise quite a bit,
+ ending up in a mixture of old processes trying to stop and new ones
+ trying to do some work.
From 2.4.24 onward, mpm-event is smarter and it is able to handle