cyrus processes & maxchild

Andrew Morgan morgan at
Thu May 13 00:23:02 EDT 2010

On Wed, 12 May 2010, Maria McKinley wrote:

> Oh, also how are the ulimits different from the maxchild limits?

ulimits are limits the operating system places on processes.  Usually they 
are set via your command shell, such as bash, so you can find 
documentation with "man bash" if you search for ulimit.  These are the 
limits that can be set:

   -c     The maximum size of core files created
   -d     The maximum size of a process’s data segment
   -e     The maximum scheduling priority ("nice")
   -f     The maximum size of files written by the shell and its children
   -i     The maximum number of pending signals
   -l     The maximum size that may be locked into memory
   -m     The maximum resident set size
   -n     The maximum number of open file descriptors (most systems do not allow this  value  to  be
   -p     The pipe size in 512-byte blocks (this may not be set)
   -q     The maximum number of bytes in POSIX message queues
   -r     The maximum real-time scheduling priority
   -s     The maximum stack size
   -t     The maximum amount of cpu time in seconds
   -u     The maximum number of processes available to a single user
   -v     The maximum amount of virtual memory available to the shell
   -x     The maximum number of file locks

It is better to let Cyrus handle resource limits internally, in a 
(relatively) graceful way, rather than hit the process limits.  I only 
mention the ulimits because you can very easily reach the ulimits when you 
have large numbers of connections.


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