[Gluster-users] Memory usage high on client

Krzysztof Strasburger strasbur at chkw386.ch.pwr.wroc.pl
Wed Apr 14 08:16:26 UTC 2010

On Wed, Apr 14, 2010 at 06:33:15AM +0200, Krzysztof Strasburger wrote:
> On Wed, Apr 14, 2010 at 09:22:09AM +1000, Chris Jin wrote:
> > Hi, I got one more test today. The copying has already run for 24 hours
> > and the memory usage is about 800MB, 39.4% of the total. But there is no
> > external IP connection error. Is this a memory leak?
> Seems to be, and a very persistent one. Present in glusterfs at least 
> since version 1.3 (the oldest I used).
> Krzysztof
I corrected the subject, as the memory usage is high on the client side
(glusterfs is the client process, glusterfsd is the server and it never
used that lot of memory on my site).
I did some more tests with logging. Accordingly to my old valgrind report,
huge amounts of memory were still in use at exit, and these were allocated
in __inode_create and __dentry_create. So I added log points in these functions
and performed the "du test", ie. mounted the glusterfs directory containing
a large number of files with log level set to TRACE , ran du on it,
then echo 3 > /proc/sys/vm/drop_caches, waiting a while until the log file
stopped growing, finally umounted and checked the (huge) logfile:
prkom13:~# grep inode_create /var/log/glusterfs/root-loop-test.log |wc -l
prkom13:~# grep inode_destroy /var/log/glusterfs/root-loop-test.log |wc -l
prkom13:~# grep dentry_create /var/log/glusterfs/root-loop-test.log |wc -l
prkom13:~# grep dentry_unset /var/log/glusterfs/root-loop-test.log |wc -l

Do you see? Everything seems to be OK, a number of inodes created, 1 less
destroyed (probably the root inode), same number of dentries created and
destroyed. The memory should be freed (there are calls to free in inode_destroy
and dentry_unset functions), but it is not. Any ideas, what is going on?
Glusterfs developers - is something kept in the lists, where inodes
and dentries live, and interleaved with these inodes and entries, so that
no memory page can be unmapped? 
We should also look at the kernel - why it does not send forgets immediately,
even with drop_caches=3?

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