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https://issues.apache.org/jira/browse/CAMEL-25520?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Work on CAMEL-25520 started by shashank.
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> camel-google-mail - google-mail-stream consumer routes a message again while
> its first exchange is still in flight (asynchronous routes)
> ----------------------------------------------------------------------------------------------------------------------------------------
>
> Key: CAMEL-25520
> URL: https://issues.apache.org/jira/browse/CAMEL-25520
> Project: Camel
> Issue Type: Bug
> Components: camel-google-mail-stream
> Reporter: shashank
> Assignee: shashank
> Priority: Major
>
> {{GoogleMailStreamConsumer.processBatch}} hands each exchange to the route
> with {{getAsyncProcessor().process(exchange, EmptyAsyncCallback.get())}}
> (line 136 at main 5af71ab258b8) and returns without waiting; the message is
> marked as read ({{markAsRead=true}}, the default since CAMEL-16329) only by
> the exchange's on completion ({{processCommit}}, lines 120-133 and 145-166).
> When the route continues asynchronously, for example {{to("seda:...")}} (seda
> hands the on completion over to its consumer), an asynchronous producer such
> as kafka, or {{threads()}}, the poll thread returns, and the next poll (500
> ms later by default) lists the message again (it is still unread, and the
> default query is {{is:unread}}), gets it again and routes it a second time,
> and so on for as long as the first exchange runs.
> When one of these duplicates fails, its rollback ({{processRollback}}, lines
> 170-188) adds the UNREAD label back, also when another exchange of the same
> message has already completed and marked it read, so a message that was
> processed successfully is consumed once more by a later poll.
> h3. Reproduction
> New {{GoogleMailStreamConsumerInProgressTest}} with a Gmail client whose
> transport answers from an in-memory mailbox ({{FakeGmailClientFactory}},
> google-http-client {{MockHttpTransport}}: labels, list of unread messages,
> get, modify): one unread message, route
> {{google-mail-stream://index?clientId=id&clientSecret=secret&delay=10}} to
> {{seda:hold}}; the seda route holds the exchange until the consumer has
> completed a second poll (counted with a {{pollStrategy}}). On main:
> {noformat}
> m1 was consumed again by a later poll while its first exchange was still in
> flight ==> expected: <1> but was: <2>
> {noformat}
> h3. Proposed fix
> The consumer keeps the ids of the messages whose exchanges are in progress (a
> set in the consumer, as the in-progress repository of aws2-s3): a poll skips
> them; an id is added before the message is fetched and released when its
> exchange completes or fails (in the on completion, after marking read or
> unread), and when the poll does not process it (get failure, consumer
> stopping). No new option; the set is not cleared when the route is stopped
> (ids of exchanges still in flight are released when they complete), and an
> exchange that never completes keeps its message reserved. With
> {{markAsRead=false}} a message is now consumed again only after its previous
> exchange completed (before, every poll routed it again, also while it was in
> flight); 4.23 upgrade-guide note. Two more tests check that a message whose
> exchange failed is consumed again and then marked as read
> ({{failedMessageIsConsumedAgain}}), and that a message whose exchange a
> stopping consumer did not process is not left in progress
> ({{notProcessedMessageIsConsumedAgain}}); both pass on main too, which has no
> in-progress set, and guard the releases on failure and on stop (the second
> one fails when the release on stop is removed). camel-google-mail unit tests:
> 47, 0 failures.
> Found with a TLA+ model of the poll (list unread, get, dispatch, stop of the
> batch) and the asynchronous completion (mark read) or failure (mark unread):
> "a message is routed again only after an exchange for it failed" is violated
> in 10 steps (poll, get, dispatch, poll again, get, dispatch again); with
> failures, "a message processed successfully is not routed again" is violated
> too (a duplicate fails after the first completed). With a synchronous route
> all properties hold; with the fix they hold also with failures, and no id
> stays in progress when nothing is in flight. Then confirmed with the real
> consumer as above.
> Affected: main, camel-4.22.x, camel-4.18.x, camel-4.14.x (same code).
> Duplicate check (2026-10-10): JIRA component camel-google-mail-stream (5
> issues: raw body, markAsRead default, verifier; none about duplicates), text
> "GoogleMailStreamConsumer" (4, none related), component camel-google-mail
> since 2023 (2, unrelated); GitHub pull requests "google-mail stream": 4
> merged, none about in-flight messages; no open PR touches camel-google-mail.
> _Filed with Claude Code on behalf of allthingssecurity._
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