Reduce cluster update reroutes with async fetch #11421
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When using async fetch, we can end up with cluster updates and reroutes based on teh number of shards. While not disastrous we can optimize it, since a single reroute is enough to apply to all the async fetch results that arrived during that time.
| logger.trace("{} already has pending reroute, ignoring {}", shardId, reason); | ||
| return; | ||
| } | ||
| clusterService.submitStateUpdateTask("async_shard_fetch", Priority.HIGH, new ClusterStateUpdateTask() { |
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I think it would be valuable to have the original type, shardId, and reason in the message, did you remove it on purpose?
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my thought that it becomes less relevant, since a single reroute actually represents a few events now, and it can be misleading seeing in the pending task information about a shard id, where it might be ones for multiple ones
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left one comment about removing info from the message, other than that LGTM |
clintongormley
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>enhancement
:Distributed/Recovery
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@dakrone I added a comment back, tell me if it makes sense |
bleskes
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After asynchronously fetching shard information the gateway allocator issues a reroute via a cluster state update task. elastic#11421 introduced an optimization trying to avoid submitting unneeded reroutes when results for many shards come in together. This is done by having a rerouting flag, indicating a pending reroute is coming and thus any new incoming shard info doesn't need to issue a reroute. This flag wasn't reset upon an error in the reroute update task. Most notably - if a master node had to step during to a min_master_node violation, it could reject an ongoing reroute. Lacking to reset the flag causing it to skip any future reroute, when the node became master again.
bleskes
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After asynchronously fetching shard information the gateway allocator issues a reroute via a cluster state update task. #11421 introduced an optimization trying to avoid submitting unneeded reroutes when results for many shards come in together. This is done by having a rerouting flag, indicating a pending reroute is coming and thus any new incoming shard info doesn't need to issue a reroute. This flag wasn't reset upon an error in the reroute update task. Most notably - if a master node had to step during to a min_master_node violation, it could reject an ongoing reroute. Lacking to reset the flag causing it to skip any future reroute, when the node became master again. Closes #11519
bleskes
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Jun 5, 2015
After asynchronously fetching shard information the gateway allocator issues a reroute via a cluster state update task. #11421 introduced an optimization trying to avoid submitting unneeded reroutes when results for many shards come in together. This is done by having a rerouting flag, indicating a pending reroute is coming and thus any new incoming shard info doesn't need to issue a reroute. This flag wasn't reset upon an error in the reroute update task. Most notably - if a master node had to step during to a min_master_node violation, it could reject an ongoing reroute. Lacking to reset the flag causing it to skip any future reroute, when the node became master again. Closes #11519
bleskes
added a commit
that referenced
this pull request
Jun 5, 2015
After asynchronously fetching shard information the gateway allocator issues a reroute via a cluster state update task. #11421 introduced an optimization trying to avoid submitting unneeded reroutes when results for many shards come in together. This is done by having a rerouting flag, indicating a pending reroute is coming and thus any new incoming shard info doesn't need to issue a reroute. This flag wasn't reset upon an error in the reroute update task. Most notably - if a master node had to step during to a min_master_node violation, it could reject an ongoing reroute. Lacking to reset the flag causing it to skip any future reroute, when the node became master again. Closes #11519
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When using async fetch, we can end up with cluster updates and reroutes based on teh number of shards. While not disastrous we can optimize it, since a single reroute is enough to apply to all the async fetch results that arrived during that time.