Re: [Gluster-devel] GlusterFS FUSE client leaks summary — part I

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Hi,

On 01/02/16 09:54, Soumya Koduri wrote:


On 02/01/2016 01:39 PM, Oleksandr Natalenko wrote:
Wait. It seems to be my bad.

Before unmounting I do drop_caches (2), and glusterfs process CPU usage
goes to 100% for a while. I haven't waited for it to drop to 0%, and
instead perform unmount. It seems glusterfs is purging inodes and that's
why it uses 100% of CPU. I've re-tested it, waiting for CPU usage to
become normal, and got no leaks.

Will verify this once again and report more.

BTW, if that works, how could I limit inode cache for FUSE client? I do
not want it to go beyond 1G, for example, even if I have 48G of RAM on
my server.

Its hard-coded for now. For fuse the lru limit (of the inodes which are
not active) is (32*1024).

This is not exact for current implementation. The inode memory pool is configured with 32*1024 entries, but the lru limit is set to infinite: currently inode_table_prune() takes lru_limit == 0 as infinite, and the inode table created by fuse is initialized with 0.

Anyway this should not be a big problem in normal conditions. After having fixed the incorrect nlookup count for "." and ".." directory entries, when the kernel detects memory pressure and sends inode forgets, the memory will be released.

One of the ways to address this (which we were discussing earlier) is to
have an option to configure inode cache limit.

I think this will need more thinking. I've made a fast test forcing lru_limit to a small value and weird errors have appeared (probably from inodes being expected to exist when kernel sends new requests). Anyway I haven't spent time on this. I haven't tested in on master either.

Xavi

If that sounds good, we
can then check on if it has to be global/volume-level, client/server/both.

Thanks,
Soumya


01.02.2016 09:54, Soumya Koduri написав:
On 01/31/2016 03:05 PM, Oleksandr Natalenko wrote:
Unfortunately, this patch doesn't help.

RAM usage on "find" finish is ~9G.

Here is statedump before drop_caches: https://gist.github.com/
fc1647de0982ab447e20

[mount/fuse.fuse - usage-type gf_common_mt_inode_ctx memusage]
size=706766688
num_allocs=2454051


And after drop_caches: https://gist.github.com/5eab63bc13f78787ed19

[mount/fuse.fuse - usage-type gf_common_mt_inode_ctx memusage]
size=550996416
num_allocs=1913182

There isn't much significant drop in inode contexts. One of the
reasons could be because of dentrys holding a refcount on the inodes
which shall result in inodes not getting purged even after
fuse_forget.


pool-name=fuse:dentry_t
hot-count=32761

if  '32761' is the current active dentry count, it still doesn't seem
to match up to inode count.

Thanks,
Soumya

And here is Valgrind output:
https://gist.github.com/2490aeac448320d98596

On субота, 30 січня 2016 р. 22:56:37 EET Xavier Hernandez wrote:
There's another inode leak caused by an incorrect counting of
lookups on directory reads.

Here's a patch that solves the problem for
3.7:

http://review.gluster.org/13324

Hopefully with this patch the
memory leaks should disapear.

Xavi

On 29.01.2016 19:09, Oleksandr

Natalenko wrote:
Here is intermediate summary of current memory

leaks in FUSE client

investigation.

I use GlusterFS v3.7.6

release with the following patches:
===

Kaleb S KEITHLEY (1):
fuse: use-after-free fix in fuse-bridge, revisited

Pranith Kumar K

(1):
mount/fuse: Fix use-after-free crash

Soumya Koduri (3):
gfapi: Fix inode nlookup counts

inode: Retire the inodes from the lru

list in inode_table_destroy

upcall: free the xdr* allocations
===


With those patches we got API leaks fixed (I hope, brief tests show

that) and

got rid of "kernel notifier loop terminated" message.

Nevertheless, FUSE

client still leaks.

I have several test

volumes with several million of small files (100K…2M in

average). I

do 2 types of FUSE client testing:
1) find /mnt/volume -type d
2)

rsync -av -H /mnt/source_volume/* /mnt/target_volume/

And most

up-to-date results are shown below:
=== find /mnt/volume -type d

===

Memory consumption: ~4G

Statedump:
https://gist.github.com/10cde83c63f1b4f1dd7a

Valgrind:
https://gist.github.com/097afb01ebb2c5e9e78d

I guess,

fuse-bridge/fuse-resolve. related.

=== rsync -av -H

/mnt/source_volume/* /mnt/target_volume/ ===

Memory consumption:
~3.3...4G

Statedump (target volume):
https://gist.github.com/31e43110eaa4da663435

Valgrind (target volume):
https://gist.github.com/f8e0151a6878cacc9b1a

I guess,

DHT-related.

Give me more patches to test :).

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