httpd is creating large number of shared memory segments.

["Chandranshu ." <chandranshu@xxxxxxxxx>]

Hi

We're running http-2.2.3 with preform MPM and host around 500 sites for many users. We always do a graceful restart of the server lest some users lose their session. The server has created a large number of shared memory segments. We have seen it creating as many as 4030 segments and this number consistently stays above 1500.

Doing ipcs -m shows that many of these segments have been marked for destruction but are still attached to some processes. Doing a grep on the pid of the process that last attached the segment returns nothing. Doing it in a while loop revealed that there were numerous httpd processes being spawned that attached the shm segment for a brief time before vanishing.

Why are there so many shared memory segments and are they not freed up by the main process?Also, could someone please guide me as to why are the processes dying so fast and replaced by new processes? I guess it has something to do with the following config:
<IfModule prefork.c>
  StartServers      2
  MinSpareServers   10
  MaxSpareServers   25
  ServerLimit     1024
  MaxClients      1024
  MaxRequestsPerChild  4000
</IfModule>

Thanks and regards
Chandranshu