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https://issues.apache.org/jira/browse/CAMEL-24979?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Guillaume Nodet updated CAMEL-24979:
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Fix Version/s: 4.23.0
> camel-core - Deprecate exchange pooling
> ---------------------------------------
>
> Key: CAMEL-24979
> URL: https://issues.apache.org/jira/browse/CAMEL-24979
> Project: Camel
> Issue Type: Task
> Components: camel-core
> Reporter: Claus Ibsen
> Assignee: Guillaume Nodet
> Priority: Major
> Fix For: 4.23.0
>
>
> Mark exchange pooling as deprecated (to be removed in a future release).
> Exchange pooling (CAMEL-16222) and the pooled internal routing tasks
> (CAMEL-16279) were added in Camel 3.9 (2021) to reduce object allocations.
> The feature has always been opt-in ({{camel.main.exchange-factory =
> pooled}}), and the default is prototype.
> *Why deprecate*
> * It is complicated. Recycling an exchange is only safe if nothing keeps a
> reference to it after it is done, but aggregation strategies, async
> callbacks, onCompletion, wire tap and SEDA queues can all hold on to
> exchanges. Lifecycle bugs still turn up years later, for example CAMEL-23686
> (clock reset on the wrong exchange in PooledProcessorExchangeFactory).
> * It is legacy on a modern JVM. Short-lived small objects are the cheapest
> thing current garbage collectors (G1, ZGC) handle. Pooled objects become
> long-lived and move to the old generation, so the gain from pooling is
> questionable and it may even cost more.
> * Other frameworks do not do this kind of object pooling of their message or
> request objects.
> * It is a maintenance burden. Every change in the routing engine must keep
> both modes correct, and some bugs only exist in pooled mode. For example,
> pooled internal tasks keep a states array sized when they were created (found
> in the CAMEL-24978 review).
> *Scope*
> * Deprecate the {{pooled}} value of the {{exchangeFactory}} option in
> camel-main (and Spring Boot / Quarkus configuration), including
> {{exchangeFactoryCapacity}} and {{exchangeFactoryStatisticsEnabled}}.
> * Deprecate PooledExchangeFactory, PooledProcessorExchangeFactory and the
> related classes, and log a WARN when pooling is enabled.
> * Mark the exchange-pooling.adoc documentation page as deprecated.
> * Add an upgrade guide entry.
> * Removal (including CamelInternalPooledTaskFactory and the pooled tasks in
> the routing engine) is left for a later release.
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