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https://issues.apache.org/jira/browse/CASSANDRA-15158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17095596#comment-17095596
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Stefan Miklosovic commented on CASSANDRA-15158:
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Hi [~bdeggleston],
please review this one
[https://github.com/smiklosovic/cassandra/tree/CASSANDRA-15158]
Sorry for the fuss but this seems to be more problematic than I was thinking
initially.
I do not think that we have to _check_ that respective migration request is
successful or not, we should just check it all schemas match ...
The logic is based on repeated checking if schemas agree or not and only in
case all schemas are equal we proceed, otherwise an exception is thrown (this
might be reworked in such sense that we just log this). There is a global
timeout for this check, it will be obvious from reading the code.
There is a test added too, because of the nature of the test, I had to "inject"
these callbacks into respective methods so I could modify their default
behaviour and test their state.
This is against 3.11, we need to backport this to 3.0 for our customer.
> Wait for schema agreement rather then in flight schema requests when
> bootstrapping
> ----------------------------------------------------------------------------------
>
> Key: CASSANDRA-15158
> URL: https://issues.apache.org/jira/browse/CASSANDRA-15158
> Project: Cassandra
> Issue Type: Bug
> Components: Cluster/Gossip, Cluster/Schema
> Reporter: Vincent White
> Assignee: Ben Bromhead
> Priority: Normal
>
> Currently when a node is bootstrapping we use a set of latches
> (org.apache.cassandra.service.MigrationTask#inflightTasks) to keep track of
> in-flight schema pull requests, and we don't proceed with
> bootstrapping/stream until all the latches are released (or we timeout
> waiting for each one). One issue with this is that if we have a large schema,
> or the retrieval of the schema from the other nodes was unexpectedly slow
> then we have no explicit check in place to ensure we have actually received a
> schema before we proceed.
> While it's possible to increase "migration_task_wait_in_seconds" to force the
> node to wait on each latche longer, there are cases where this doesn't help
> because the callbacks for the schema pull requests have expired off the
> messaging service's callback map
> (org.apache.cassandra.net.MessagingService#callbacks) after
> request_timeout_in_ms (default 10 seconds) before the other nodes were able
> to respond to the new node.
> This patch checks for schema agreement between the bootstrapping node and the
> rest of the live nodes before proceeding with bootstrapping. It also adds a
> check to prevent the new node from flooding existing nodes with simultaneous
> schema pull requests as can happen in large clusters.
> Removing the latch system should also prevent new nodes in large clusters
> getting stuck for extended amounts of time as they wait
> `migration_task_wait_in_seconds` on each of the latches left orphaned by the
> timed out callbacks.
>
> ||3.11||
> |[PoC|https://github.com/apache/cassandra/compare/cassandra-3.11...vincewhite:check_for_schema]|
> |[dtest|https://github.com/apache/cassandra-dtest/compare/master...vincewhite:wait_for_schema_agreement]|
>
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