shmem release

Tim Traver tt-list at
Tue Mar 30 12:34:41 PST 2004

Thanks Sean,

that points me more in the right direction...

I have changed the mutex values for mod_ssl, and we'll see if that causes 
the problem to go away, and I'll look into the amount of shmmaxpgs is set 
up on the box...


At 12:10 PM 3/30/2004, Sean Chittenden wrote:
>>Ok, I am running a 4.7 FreeBSD box that is a web server running apache.
>>It looks like some module that I have is leaking memory, and
>>eventually, apache crashes on restarts becuase of this error :
>>shmget() failed:  No space left on device
>Look in your logs and see if there's an error message being logged that
>could help you identify what module it is.  Otherwise, get a crash dump
>of a crashed process and run gdb on it to see if the module that's
>crashing is obvious from the back trace.
>>which means it can't get any more memory, which I understand.
>>When I look at the top list, it shows me something like this :
>>Mem: 140M Active, 879M Inact, 151M Wired, 181M Cache, 199M Buf, 660M
>>But when you look at the processes that are still up, they hardly take
>>up any memory.
>>So, my question is this.
>>Is there a way to free up Inactive memory from crashed processes ???
>You don't need to worry about that.
>There's a better article that I remember reading that went into great
>detail explaining this, but I can't seem to dig it up.
>>Without just rebooting the box ???
>Inactive, buffered, cached, and free memory is memory that the system
>will use to fulfill memory allocation requests (ie, don't worry about
>it, your box has plenty of memory available).
>>I know that I need to find the source of the leaking and crashing to
>>begin with, but in the mean time, if it happens, I'd like to free up
>>the memory manually, so I can get the box running again...
>shmget() means you've run out of semaphores, not RAM.  From
>postgresql's post-install-notes:
>To allow many simultaneous connections to your PostgreSQL server, you
>should raise the SystemV shared memory limits in your kernel. Here are
>example values for allowing up to 180 clients (tinkering in
>postgresql.conf also needed, of course):
>   options         SYSVSHM
>   options         SYSVSEM
>   options         SYSVMSG
>   options         SHMMAXPGS=65536
>   options         SEMMNI=40
>   options         SEMMNS=240
>   options         SEMUME=40
>   options         SEMMNU=120
>You don't have a RAM issue or memory leak, but you're running into a
>limit for the number semaphores.  Dime to dollar you've got mod_ssl
>installed and its using semaphore locking and not using a file.  Google
>is your friend, this is a pretty common configuration problem/task that
>many run into.  -sc
>Sean Chittenden
>freebsd-performance at mailing list
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