Fix/spurious subdisable mid transaction restarts and apply-idle-timeout misclassification - #607
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Fix/spurious subdisable mid transaction restarts and apply-idle-timeout misclassification#607rasifr wants to merge 4 commits into
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No actionable comments were generated in the recent review. 🎉 ℹ️ Recent review info⚙️ Run configurationConfiguration used: Organization UI Review profile: CHILL Plan: Team Run ID: 📒 Files selected for processing (3)
Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review. 📝 WalkthroughWalkthroughChangesThe change adds a provider transaction-stall injection point. It classifies idle timeouts as connection failures and clears transient state after worker restarts. A scheduled TAP test covers both scenarios. Apply worker exception handling
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Merge Risk: ⚪ Minimal · up to This change prevents clean apply-worker restarts and provider idle timeouts from being misclassified as apply failures, avoiding erroneous subscription disablement while allowing normal reconnection and retransmission. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
Full details: Title checkExplanation The title clearly identifies both main fixes: spurious subscription disabling after mid-transaction worker restarts and apply-idle-timeout misclassification. It is somewhat awkwardly phrased but remains specific and related to the changeset. Full details: Docstring CoverageExplanation Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 4 files. (1 skipped: 1 unsupported.) ✨ Finishing Touches📝 Generate docstrings
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In `@tests/tap/t/046_apply_worker_exception_misclassification.pl`:
- Around line 223-236: The scenario 2 test must verify that the apply idle
timeout actually fired, not only that the subscription remained enabled. Record
the apply-worker PID before the provider stall, then before
injection_points_wakeup() assert that the original worker has exited or its PID
has changed after the timeout, while preserving the existing subscription-state
assertion.
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ℹ️ Review info
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Configuration used: Organization UI
Review profile: CHILL
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Run ID: bb8e14aa-a509-45fb-b5a8-91eeac74938b
📒 Files selected for processing (6)
include/spock_injection.hsrc/spock_apply.csrc/spock_injection.csrc/spock_output_plugin.ctests/tap/scheduletests/tap/t/046_apply_worker_exception_misclassification.pl
Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.
SPOCK_WORKER_DELAY() only covers the subscriber side (apply-worker start/finish). Add SPOCK_OUTPUT_TXN_STALL() for the provider side, called at the end of pg_decode_begin_txn() right after BEGIN is flushed to the subscriber, so a test can make the walsender go quiet mid-transaction. Same SPOCK_RANDOM_DELAYS / USE_INJECTION_POINTS / neither pattern as the existing macro, including firing spock_random_delay() under SPOCK_RANDOM_DELAYS for parity. No-op in production; no behavioral change.
Two related bugs in the apply worker's restart/exit machinery: a non-error event is misread as evidence of a prior apply failure, entering exception replay and, under spock.exception_behaviour = sub_disable, disabling a healthy subscription. Scenario 1: a mid-transaction worker restart (e.g. sub_alter_options()) can match a stale exception_log commit_lsn on reconnect. Scenario 2: spock.apply_idle_timeout's error isn't tagged connection-class, so a stalled provider is misclassified as a data conflict; reproduced via the spock-output-txn-stall injection point, which requires --enable-injection-points. It also asserts the apply worker's PID actually changes across the stall (recorded via application_name = "spock apply <dboid>:<subid>"), proving the idle-timeout reconnect path really fired rather than just observing that nothing broke -- a reconnect attempt right after the timeout typically fails immediately on "replication slot is active" (the old, still-stalled walsender hasn't released it) and the worker dies again in milliseconds, so an empty PID counts as evidence of restart too, not only a differing non-empty one. Both scenarios share one cluster/subscription. Only scenario 2 (and the provider restart it needs) is skipped when injection_points is unavailable -- scenario 1 has no such dependency and always runs. Predates both fixes, so scenario 1's 4 subtests and scenario 2's 7 (when not skipped) fail as expected; the next two commits fix each in turn.
handle_begin() stamps exception_log->commit_lsn on every BEGIN, not just failures, and nothing cleared it on a clean SIGTERM exit. A restart landing mid-transaction let the provider's retransmission of that same transaction match the stale commit_lsn and get misread as a prior failure, disabling the subscription for no real error. Clear the marker via the existing clear_transient_exception_state() helper when apply_work() exits on got_SIGTERM. Fixes scenario 1 of 046_apply_worker_exception_misclassification.pl.
spock.apply_idle_timeout's "no data received... reconnecting" error was a bare elog(ERROR), defaulting to ERRCODE_INTERNAL_ERROR. The PG_CATCH discriminator in apply_work() only recognizes connection-class sqlerrcodes, so a merely-slow or stalled provider mid-transaction fell into the same branch as a genuine data conflict, spuriously disabling the subscription (or silently discarding a good transaction). Tag the error ERRCODE_CONNECTION_FAILURE, consistent with the other stream-level errors nearby, routing it through the already-correct connection-class branch. Fixes scenario 2 of 046_apply_worker_exception_misclassification.pl; all subtests now pass (or skip cleanly without --enable-injection-points).
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There are two problams:
1- mid-transaction worker restart
handle_begin() stamps exception_log->commit_lsn on every BEGIN, not just failures, and nothing cleared it on a clean SIGTERM exit (e.g. sub_alter_options() restarting the worker to pick up a new setting). If the restart lands mid-transaction, the provider's ordinary retransmission of that same transaction matches the stale commit_lsn on the replacement worker's first BEGIN, which is misread as a prior apply failure.
2- apply-idle-timeout misclassification
spock.apply_idle_timeout's "no data received... reconnecting" error was a bare elog(ERROR), defaulting to ERRCODE_INTERNAL_ERROR. The apply worker's connection-class error discriminator doesn't recognize that code, so a merely-slow or stalled provider mid-transaction falls into the same branch as a genuine data conflict. No worker restart is even required for this one.