SOLR-17764: retry CloudSolrClient requests failing with ClosedChannelException#4643
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SOLR-17764: retry CloudSolrClient requests failing with ClosedChannelException#4643serhiy-bzhezytskyy wants to merge 1 commit into
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…Exception CloudSolrClient.wasCommError() classified only SocketException and UnknownHostException as communication errors worth retrying. A connection dropped mid-request surfaces as a ClosedChannelException (for example an HTTP/2 GOAWAY when a node shuts down), which was not retried even though maxRetries allowed it. Treat ClosedChannelException as a communication error so the request is retried on another node when one is available. Note: this does not by itself fix the graceful-shutdown failures tracked in SOLR-17764 (the underlying Jetty HTTP/2 client bug jetty#15368 discards an already-sent response, and a single-node cluster has no other node to retry on), but retrying a dropped connection is correct regardless.
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While looking into the graceful-shutdown test failures (SOLR-17764), I noticed
CloudSolrClient.wasCommError()only classifiesSocketExceptionandUnknownHostExceptionas communication errors worth retrying.A connection dropped mid-request surfaces as a
java.nio.channels.ClosedChannelException(for example an HTTP/2 GOAWAY when a node shuts down). That was not treated as a comm error, so the request was not retried even thoughmaxRetriesallowed it — the logs showcommError=falseand no retry. This is the kind of "connection error should be retried" case a couple of committers pointed at on SOLR-17764.Fix: treat
ClosedChannelExceptionas a communication error, alongside the existing two, so the request is retried on another node when one is available. Added a unit test for the classification.Scope / honesty: this does not by itself fix the graceful-shutdown failures in SOLR-17764.
TestGracefulJettyShutdown, retry cannot help because there is no other node to route to.So this is a standalone retry-robustness improvement that is correct on its own merits, not a fix for the graceful-shutdown issue. Details and experiments posted on SOLR-17764.