ulimit settings 2

[mohmin]

Hey guys,
One user is having problems running his application, whats happening is that it is giving "Heap Allocation Failed error(which indicates the job could not page data in memory)".

The user now requesta the ulimit settings on memory to be made infinite for him.

I understand its good for him, but how bad is it for the system? What are its implications?


Thank you.
Mohmin.

 

[RMGBELGIUM]

if his application has memory leaks, your system's memory wil be totally consumed, causing your machine to hang eventually...

rgrds,

R.

 

[DSMARWAY]

hi ,
It may also be worth looking at

1. hardware spec of server i.e. how much memory do you have , no. of cpus ,
2. what resources i.e. memory / server spec , does the application need in order to be run successfully
( may be worth consulting the application manual/ team )
3. It may not be a simple task just to increase the ulimit parameter , it could be the system is running out of resources , the application is not closing properly therefore not releasing large chunks of memory segments
( ipcs -a ,look for NATTACH see how many processes are attached to the memory segment , if 0 then it hasn't cleared
)

Has this problem just started to happen , or was this happen since install stage ?

ref:- umlimit man page, read below

" Note: Raising the data ulimit does not necessarily raise the program break value. If the proper memory segments are not initialized at program load time, raising your memory limit will not allow access to this memory. Also,
without these memory segments initialized, the value returned after such a change may not be the proper break value. If your data limit is RLIM_INFINITY, this value will never advance past the segment size, even if
that data is available. Use the -bmaxdata flag of the ld command to set up these segments at load time.


I would do more investigation , and see how your system is performing in general.