[client] Recover admin writes after coordinator leader failover - #4216
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litiliu wants to merge 1 commit into
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[client] Recover admin writes after coordinator leader failover#4216litiliu wants to merge 1 commit into
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A long-lived Admin client caches the coordinator leader. After failover to a standby, coordinator write operations (dropDatabase, etc.) kept failing with NotCoordinatorLeaderException because: 1. FlussAdmin wrapped only the read-only gateway with retry, so the write gateway never refreshed metadata after a failover. 2. Even after refreshing to the new leader's address, NettyClient reused the stale connection cached under the coordinator uid "cs-0" (both coordinators share id 0), so requests kept hitting the old leader that is still alive as a standby. Fixes: - RetryableGatewayClientProxy now takes separate refresh and retry predicates. The write gateway refreshes metadata on any recoverable error (NotCoordinatorLeaderException or network errors after a failover/upgrade) so the stale coordinator connection is repointed and a manual retry can recover, but auto-retries only NotCoordinatorLeaderException -- which the server rejects before invoking the write API, so a retry cannot duplicate an already-executed, non-idempotent mutation. Read-only gateways keep retrying any RetriableException. - NettyClient recreates the connection when the address for a server uid changes, closing the stale connection. Tests: - RetryableGatewayClientProxyTest: retry on the safe error; refresh-but-no-retry on network errors; no refresh/retry when neither predicate matches. - NettyClientTest: reconnect when a uid's address changes. - CoordinatorFailoverAdminITCase: keeps one Admin open across a coordinator leader failover and verifies a write succeeds afterward. Closes apache#4027
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@loserwang1024 Could you take a look on this? |
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Purpose
Linked issue: close #4027
A long-lived Java
Adminclient caches the coordinator leader inMetadataUpdater. After coordinator leadership moves to a standby, coordinator write operations (e.g.dropDatabase,createTable,alterTable) keep being sent to the old coordinator and fail withNotCoordinatorLeaderExceptionuntil the connection is recreated.Two root causes:
FlussAdminwrapped only the read-only gateway withRetryableGatewayClientProxy; the write gateway never refreshed metadata after a failover.NettyClientreused the connection cached under the coordinator uidcs-0(both coordinators share id0), so requests kept hitting the old leader that is still alive as a standby.This is an alternative implementation of #4200 and incorporates @loserwang1024's review feedback there: refresh metadata on any recoverable error, but auto-retry only the provably-safe
NotCoordinatorLeaderException.Brief change log
RetryableGatewayClientProxynow takes separaterefreshPredicateandretryPredicate. On failure it refreshes metadata whenrefreshPredicatematches, and additionally retries once only whenretryPredicatematches. Read-only gateways keep usingRetriableExceptionfor both (unchanged behavior).FlussAdminwrite gateway:refreshPredicate=NotCoordinatorLeaderException || RetriableException— refreshes metadata on any recoverable error, includingNetworkException/TimeoutExceptionwhen the old coordinator's IP is not reused after an upgrade.retryPredicate=NotCoordinatorLeaderExceptiononly — safe to auto-retry becauseFlussRequestHandlerrejects the request before invoking the write API, so the mutation was never executed. Network/timeout failures refresh metadata but surface the original error for a manual retry (non-idempotent-safe).NettyClientrecreates the connection when the address behind a server uid changes (a coordinator failover reusescs-0at a new host/port) and closes the stale connection.Tests
Run:
./mvnw -pl fluss-rpc,fluss-client -am -Dtest=RetryableGatewayClientProxyTest,NettyClientTest,CoordinatorFailoverAdminITCase -DfailIfNoSpecifiedTests=false testRetryableGatewayClientProxyTest: retry on the safe error; refresh-but-no-retry on network errors; no refresh/retry when neither predicate matches.NettyClientTest#testReconnectWhenServerAddressChangesForSameUid: a same-uid address change reconnects instead of reusing the stale connection.CoordinatorFailoverAdminITCase#testAdminWriteRecoversAfterCoordinatorFailover: keeps oneAdminopen across a coordinator leader failover and verifiesdropDatabasesucceeds afterward.API and Format
No public API or storage format changes.
RetryableGatewayClientProxy(@Internal) gains a two-predicate factory overload; the existing signature is preserved.Documentation
No. Bug fix; no user-facing feature or documentation change.
Generative AI disclosure: Yes — GitHub Copilot (Claude Opus 4.8) was used to help author this PR.