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https://issues.apache.org/jira/browse/CASSANDRA-15158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17189362#comment-17189362
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Blake Eggleston commented on CASSANDRA-15158:
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Thanks Aleksey.
Removing requestQueue is going to cause some problems, We need to have some way
of cycling requests through the entire set of endpoints reporting a given
version. Without one, if the first few endpoints to come out of the iterator
are down, we'll get stuck in a loop as we schedule pulls which will immediately
fail causing new pulls to be scheduled for the same node.
I've updated my branch with your changes and added the request queue back.
Since the storage service doesn't really need to fire off migration requests, I
also added a commit making the MigrationCoordinator an endpoint change
subscriber. So StorageService is responsible for a little less.
> Wait for schema agreement rather than 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: Blake Eggleston
> Priority: Normal
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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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