[Gluster-users] Gluster High CPU/Clients Hanging on Heavy Writes

[Yuhao Zhang]

This is a semi-production server and I can't bring it down right now. Will try to get the monitoring output when I get a chance. 

As I recall, the high CPU processes are brick daemons (glusterfsd) and htop showed they were in status D. However, I saw zero zpool IO as clients were all hanging.

> On Aug 5, 2018, at 02:38, Raghavendra Gowdappa <rgowdapp at redhat.com> wrote:
> 
> 
> 
> On Sun, Aug 5, 2018 at 12:44 PM, Yuhao Zhang <zzyzxd at gmail.com <mailto:zzyzxd at gmail.com>> wrote:
> Hi,
> 
> I am running into a situation that heavy write causes Gluster server went into zombie with many high CPU processes and all clients hangs, it is almost 100% reproducible on my machine. Hope someone can help.
> 
> Can you give us the output of monitioring these processes with High cpu usage captured in the duration when your tests are running?
> 
> MON_INTERVAL=10 # can be increased for very long runs
> top -bd $MON_INTERVAL > /tmp/top_proc.${HOSTNAME}.txt # CPU utilization by process
> top -bHd $MON_INTERVAL > /tmp/top_thr.${HOSTNAME}.txt # CPU utilization by thread
> 
> 
> I started to observe this issue when running rsync to copy files from another server and I thought it might be because Gluster doesn't like rsync's delta transfer with a lot of small writes. However, I was able to reproduce this with "rsync --whole-file --inplace", or even with cp or scp. It usually appears after starting the transfer for a few hours, but sometimes can happen within several minutes.
> 
> Since this is a single node Gluster distributed volume, I tried to transfer files directly onto the server bypassing Gluster clients, but it still caused the same issue.
> 
> It is running on top of a ZFS RAIDZ2 dataset. Options are attached. Also, I attached the statedump generated when my clients hung, and volume options.
> 
> - Ubuntu 16.04 x86_64 / 4.4.0-116-generic
> - GlusterFS 3.12.8
> 
> Thank you,
> Yuhao
> 
> 
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org <mailto:Gluster-users at gluster.org>
> https://lists.gluster.org/mailman/listinfo/gluster-users <https://lists.gluster.org/mailman/listinfo/gluster-users>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20180805/874a2610/attachment.html>