memory fragmentation issues in 1.2?

[Paul T]

Turn off the OOM killer and see what happens?

If you are running Linux, you might be surprised with
the behaviour of it's memory manager on memcached node
dedicated to memcached.

By the way - univca (that does many things what
memecached does) is using standard malloc with no
pooling, runs for months, serves billions of hits and
never got any 'memory fragmentation' issues. 

If you see the Linux box 'freezing' - check out Linux
'swappiness' parameter, the default setting of that
parameter makes no sense when running something like
dedicated memcached node, you don't want it to swap. I
think that  parameter is what caused the infamous
linux swapping and 'memory fragmentation' myth in the
first place.

Rgds.Paul.

PS. In the absense of a test that can cleary reproduce
a 'memory fragmentation' effect I suggest to call the
'memory fragmentation' and urban legend.

--- George Schlossnagle <george at omniti.com> wrote:

> Hi,
> 
> I'm seeing some weird behavior on my memcached 1.2
> instances.  Overtime
> the RSS of my processess is growing and growing.  I
> start out at around
> 800M (my configured memory size), and it
> monotonically grows (over a
> period of a couple weeks) until it is over double
> that size and gets
> killed by the OOM killer.

> Trying to duplicate this behavior under valgrind
> hasn't been very
> fruitful, which makes me suspect it's system memory
> fragmentation.
> 
> Has anyone else seen this sort of behaviour?  Is
> there some likely EBKAC
> that I might be engaging in that could cause this? 
> I have some ideas
> for working around this, but I'd much rather just be
> told I'm stupid. :)
> 
> George
> 


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