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Posted to commits@cassandra.apache.org by "Brandon Williams (JIRA)" <ji...@apache.org> on 2014/01/10 23:36:50 UTC
[jira] [Commented] (CASSANDRA-6571) Quickly restarted nodes can
list others as down indefinitely
[ https://issues.apache.org/jira/browse/CASSANDRA-6571?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13868415#comment-13868415 ]
Brandon Williams commented on CASSANDRA-6571:
---------------------------------------------
Worth noting we recently had another problem with CASSANDRA-3533 in CASSANDRA-6554
> Quickly restarted nodes can list others as down indefinitely
> ------------------------------------------------------------
>
> Key: CASSANDRA-6571
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6571
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Richard Low
> Assignee: Vijay
> Labels: gossip
> Fix For: 2.0.5
>
>
> In a healthy cluster, if a node is restarted quickly, it may list other nodes as down when it comes back up and never list them as up. I reproduced it on a small cluster running in Docker containers.
> 1. Have a healthy 5 node cluster:
> {quote}
> $ nodetool status
> Datacenter: datacenter1
> =======================
> Status=Up/Down
> |/ State=Normal/Leaving/Joining/Moving
> -- Address Load Tokens Owns (effective) Host ID Rack
> UN 192.168.100.1 40.88 KB 256 38.3% 92930ef6-1b29-49f0-a8cd-f962b55dca1b rack1
> UN 192.168.100.254 80.63 KB 256 39.6% ef15a717-9d60-48fb-80a9-e0973abdd55e rack1
> UN 192.168.100.3 87.78 KB 256 40.8% 4e6765db-97ed-4429-a9f4-8e29de247f18 rack1
> UN 192.168.100.2 75.22 KB 256 40.6% e89bc581-5345-4abd-88ba-7018371940fc rack1
> UN 192.168.100.4 80.83 KB 256 40.8% 466a9798-d484-44f0-aae8-bb2b78d80331 rack1
> {quote}
> 2. Kill a node and restart it quickly:
> bq. kill -9 <pid> && start-cassandra
> 3. Wait for the node to come back and more often than not, it lists one or more other nodes as down indefinitely:
> {quote}
> $ nodetool status
> Datacenter: datacenter1
> =======================
> Status=Up/Down
> |/ State=Normal/Leaving/Joining/Moving
> -- Address Load Tokens Owns (effective) Host ID Rack
> UN 192.168.100.1 40.88 KB 256 38.3% 92930ef6-1b29-49f0-a8cd-f962b55dca1b rack1
> UN 192.168.100.254 80.63 KB 256 39.6% ef15a717-9d60-48fb-80a9-e0973abdd55e rack1
> DN 192.168.100.3 87.78 KB 256 40.8% 4e6765db-97ed-4429-a9f4-8e29de247f18 rack1
> DN 192.168.100.2 75.22 KB 256 40.6% e89bc581-5345-4abd-88ba-7018371940fc rack1
> DN 192.168.100.4 80.83 KB 256 40.8% 466a9798-d484-44f0-aae8-bb2b78d80331 rack1
> {quote}
> From trace logging, here's what I think is going on:
> 1. The nodes are all happy gossiping
> 2. Restart node X. When it comes back up it starts gossiping with the other nodes.
> 3. Before node X marks node Y as alive, X sends an echo message (introduced in CASSANDRA-3533)
> 4. The echo message is received by Y. To reply, Y attempts to reuse a connection to X. The connection is dead, but the message is attempted anyway but fails.
> 5. X never receives the echo back, so Y isn't marked as alive.
> 6. X gossips to Y again, but because the endpoint isAlive() returns true, it never calls markAlive() to properly set Y as alive.
> I tried to fix this by defaulting isAlive=false in the constructor of EndpointState. This made it less likely to mark a node as down but it still happens.
> The workaround is to leave a node down for a while so the connections die on the remaining nodes.
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