[FLINK-39975][jdbc] Recover JdbcSourceSplitReader from a connection closed during cancellation#200
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RocMarshal merged 1 commit intoJun 23, 2026
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LGTM +1.
Thanks @laughingman7743
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…losed during cancellation When a bounded query (e.g. LIMIT) finishes the job early, the source is cancelled while the split fetcher is still opening the next split. The JDBC connection validated by the provider is torn down before the statement is prepared/executed, so Derby raises "08003: No current connection"; the fatal SQLException fails the whole job and makes DerbyDynamicTableSourceITCase.testLimit flaky. Wrap the split-open in a bounded retry: when the connection is found closed, drop it together with the stale statement/result set and re-establish it via the provider, retrying up to MAX_CONNECTION_RETRIES. A genuine query error on a healthy connection is rethrown immediately, and an unreachable database still fails the job after the retry budget, so real errors are not masked. wakeUp()/fetch() are left unchanged. Add a deterministic regression test that injects an already-closed connection (reproducing the exact 08003 and failing without the fix), plus tests for the immediate-rethrow and retry-exhaustion branches.
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Awesome work, congrats on your first merged pull request! |
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What is the purpose of the change
Fix the flaky
DerbyDynamicTableSourceITCase.testLimit(and occasionallytestProject). When a bounded query (e.g.LIMIT) finishes the job early, the source is cancelled while the split fetcher is still opening the next split; theJDBC connection validated by the provider is torn down before the statement is prepared/executed, so Derby raises
08003: No current connectionand the fatalSQLExceptionfails the whole job (the test runs underNoRestartBackoffTimeStrategy). See FLINK-39975 for the full analysis.Brief change log
JdbcSourceSplitReadernow opens a split viaopenResultSetForSplitWithReconnect, a bounded retry (MAX_CONNECTION_RETRIES = 3).connection.isClosed()); before retrying it drops the dead connection and the stale statement/result set and re-establishes via the provider. A query error on a healthyconnection is rethrown immediately, and an unreachable database still fails after the retry budget — real errors are not masked.
wakeUp()/fetch()are unchanged.Verifying this change
JdbcSourceSplitReaderTest#testFetchReconnectsWhenConnectionClosedWhileOpeningSplit, a deterministic regression test that injects an already-closed connection, reproducing the exact08003error (it fails without thischange) and asserting the reader re-establishes the connection and reads the whole split.
testFetchRethrowsImmediatelyWhenConnectionStaysOpen(a query error on a healthy connection is rethrown without reconnect) andtestFetchFailsAfterExhaustingReconnectRetries(gives up after the retry budget instead oflooping forever).
DerbyDynamicTableSourceITCasepasses repeated runs.Does this pull request potentially affect one of the following parts:
@Public(Evolving): noDocumentation