A flood of glusterd friend updates happen whenever a glusterd restarts and re-establishes all it's connections. In a large cluster (100s) nodes, this would go on for several minutes. During this period the cluster isn't able to respond to commands. Simple local commands, like `gluster volume list` will take relatively very long time to complete. When a large number of nodes come back up simultaneously, say due to a network problem, this flood can last for a long time, longer than expected.
REVIEW: http://review.gluster.org/12999 (glusterd: reduce friend update flood) posted (#1) for review on master by Kaushal M (kaushal)
REVIEW: http://review.gluster.org/12999 (glusterd: reduce friend update flood) posted (#2) for review on master by Kaushal M (kaushal)
COMMIT: http://review.gluster.org/12999 committed in master by Atin Mukherjee (amukherj) ------ commit f624abd6885752eeaa8d07101ff00f52af48de26 Author: Kaushal M <kaushal> Date: Thu Dec 17 11:13:36 2015 +0530 glusterd: reduce friend update flood When in a befriended state, glusterd would broadcast friend updates to all other peers whenver a ACC or LOCAL_ACC event occurred. When a downed glusterd came back up and established connections again, this lead to a flood of friend updates to happen on the order of N^2 (N is the number of peers in the cluster) In larger clusters this was problematic, and could lead to very long times for the cluster to settle down when a peer came back up. Multiple peers coming back up at the same time would compound the problem. Broadcasting of friend updates doesn't have much use in places other that during a peer probe. Instead of broadcasting friend updates on connection re-establishment, updates can just be exchanged between the peers involved in the connection. This patch changes the glusterd friend state-machine to send updates only to the required peer for ACC or LOCAL_ACC events when in befriended state. The number of updates sent now is in the order of N. For a 10 node cluster, the number of updates reduced by 5 times. When creating the 10 node cluster, the updates reduced from ~500 to ~150. When a glusterd restarted, the number of exchanges reduced from ~160 to ~35. BUG: 1292749 Change-Id: Ib6072090c7069b081d018cdaa3dc878819ab1d18 Signed-off-by: Kaushal M <kaushal> Reviewed-on: http://review.gluster.org/12999 Reviewed-by: Atin Mukherjee <amukherj> Tested-by: NetBSD Build System <jenkins.org> Tested-by: Gluster Build System <jenkins.com>
This bug is getting closed because a release has been made available that should address the reported issue. In case the problem is still not fixed with glusterfs-3.8.0, please open a new bug report. glusterfs-3.8.0 has been announced on the Gluster mailinglists [1], packages for several distributions should become available in the near future. Keep an eye on the Gluster Users mailinglist [2] and the update infrastructure for your distribution. [1] http://blog.gluster.org/2016/06/glusterfs-3-8-released/ [2] http://thread.gmane.org/gmane.comp.file-systems.gluster.user