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

[Xavier Hernandez]

Hi Oleksandr,

On 01/02/16 09:09, 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.

That's the expected behavior after applying the nlookup count patch. As 
it's configured now, gluster won't release memory until the kernel 
requests it. Forcing a drop caches causes this to be made massively, 
consuming a lot of CPU. On normal circumstances, when memory is low, 
kernel will start releasing cached entries. This will include requests 
to gluster to release memory associated with those inodes in an 
incremental way as it's needed.

> 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.

I've made the same experiment and I ended with only 4 inodes still in 
use (probably the root directory and some other special entries) after 
having had several tens of thousands.

Xavi

>
> 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.
>
> 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 :).
>>>>
>>>> _______________________________________________
>>>>
>>>>> Gluster-devel mailing
>>>>
>>>> list
>>>>
>>>>> Gluster-devel at gluster.org
>>>>
>>>> http://www.gluster.org/mailman/listinfo/gluster-devel
>>>
>>>
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