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https://issues.apache.org/jira/browse/CASSANDRA-17808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17829621#comment-17829621
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Paul Chandler commented on CASSANDRA-17808:
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[~smiklosovic] and [~maedhroz] I can see that there is a PR for this change in
4.1, but it has not been committed. Are there any plans to do that.?
We would like to port it to 4.0 as we are having the same problem for a large
4.0 cluster, so we would be able to provide a patch for 4.0, but I wanted to
check there were no issues with the 4.1 version first that are stopping it
being committed?
> Optionally avoid hint transfer during decommission
> --------------------------------------------------
>
> Key: CASSANDRA-17808
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17808
> Project: Cassandra
> Issue Type: Improvement
> Components: Consistency/Hints
> Reporter: Caleb Rackliffe
> Assignee: Caleb Rackliffe
> Priority: Normal
> Fix For: 5.0-alpha1, 5.0
>
> Time Spent: 1h 50m
> Remaining Estimate: 0h
>
> Both because they aren’t strictly necessary to maintain consistency, and
> because throttling induced by their rate-limiter (see
> {{hinted_handoff_throttle}}) may stall progress, transferring hints during
> decommission (specifically unbootstrap) rather than just pausing, disabling,
> and truncating them probably doesn’t make sense. The only other concern would
> be the BatchLog, which nominally depends on hint delivery to maintain its
> "guarantees". However, during BatchLog replay on unbootstrap,
> {{ReplayingBatch}} ignores batches older the gcgs anyway.
> Here's a proposal from [~aleksey] that might strike a reasonable balance:
> 1.) We continue to transfer hints by default during decommission, but at a
> higher rate. We could, for instance, stop having {{DispatchHintsTask}} divide
> its effective rate by the number of nodes in the cluster.
> {noformat}
> int nodesCount = Math.max(1,
> StorageService.instance.getTokenMetadata().getAllEndpoints().size() - 1);
> double throttleInBytes = DatabaseDescriptor.getHintedHandoffThrottleInKiB() *
> 1024.0 / nodesCount;
> this.rateLimiter = RateLimiter.create(throttleInBytes == 0 ? Double.MAX_VALUE
> : throttleInBytes);
> {noformat}
> 2.) We provide an option to simply avoid transferring hints during
> unbootstrap. Even this would only take the BatchLog from "best effort" to
> "slightly less effort" ;)
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