CAMEL-23281: fix split/aggregate deadlock with SynchronousExecutorService in transacted routes#22493
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Croway merged 1 commit intoapache:camel-4.18.xfrom Apr 8, 2026
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…vice in transacted routes Process aggregate completion inline for SynchronousExecutorService instead of going through the reactive queue. The CAMEL-23030 change from scheduleSync to schedule causes a deadlock when the surrounding split is transacted: the nested await/executeFromQueue cycles interact with Pipeline.scheduleMain queue swapping, making pending tasks unreachable.
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Backport of #22492 to camel-4.18.x.
Summary
SynchronousExecutorServicewith split + aggregate in transacted routesscheduleSync(task)toschedule(task)forSynchronousExecutorService. The aggregated exchange loses the transacted flag (Exchange.copy()doesn't preserve it), so this new branch is always taken.schedule()queues the completion task, but the surrounding transacted split creates nestedawait → executeFromQueuecycles wherePipeline.scheduleMain()queue swapping makes the task unreachable — deadlock.processor.process(exchange, callback)forSynchronousExecutorService, bypassing the reactive queue entirely.Test plan
SplitAggregateInChoiceSynchronousExecutorTest— 3 tests (non-transacted, transacted, transacted+choice)SplitAggregateSynchronousExecutorStackOverflowIssueTest— CAMEL-23030 regression guard passes