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https://issues.apache.org/jira/browse/CAMEL-25292?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Claus Ibsen resolved CAMEL-25292.
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Resolution: Fixed
Fixed via https://github.com/apache/camel/pull/27323
> camel-plc4x - a stopped triggered consumer keeps its scraper running
> (exchanges after stop, duplicates after a restart), and the triggered
> consumer cannot start without jackson-databind
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: CAMEL-25292
> URL: https://issues.apache.org/jira/browse/CAMEL-25292
> Project: Camel
> Issue Type: Bug
> Reporter: shashank
> Assignee: shashank
> Priority: Major
> Fix For: 4.23.0
>
>
> h3. 1. The scraper is never stopped
> With a {{trigger}}, {{Plc4XConsumer.doStart}} creates a
> {{TriggerCollectorImpl}} and a {{TriggeredScraperImpl}}, starts them, and
> keeps them only in local variables of {{startTriggered()}}. {{doStop}} only
> cancels the future of the one-time (untriggered) read, so the scraper and the
> collector keep running:
> * after the route is stopped, the scraper keeps reading the PLC at the
> configured period and sends the exchanges of every triggered read to the
> route;
> * after the route is started again (a new consumer, a new scraper), the old
> and the new scraper both run, so every triggered read is routed twice (once
> more per restart), and the PLC gets the reads of every scraper.
> The consumer also creates its own
> {{Executors.newSingleThreadScheduledExecutor()}} per instance for the
> one-time read and never shuts it down (one thread leaked per consumer, also
> for triggered consumers, which do not use it).
> h3. 2. The triggered consumer fails to start with camel-plc4x alone
> {{camel-plc4x}} excludes {{jackson-databind}} from {{plc4j-scraper}}, but
> {{ScraperConfigurationTriggeredImpl}} (built in {{getScraperConfig}}) needs
> it. Without {{jackson-databind}} from another dependency, the triggered
> consumer fails in {{doStart}}:
> {noformat}
> java.lang.NoClassDefFoundError:
> com/fasterxml/jackson/databind/exc/MismatchedInputException
> at
> org.apache.camel.component.plc4x.Plc4XConsumer.getScraperConfig(Plc4XConsumer.java:153)
> at
> org.apache.camel.component.plc4x.Plc4XConsumer.startTriggered(Plc4XConsumer.java:124)
> {noformat}
> ({{mvn dependency:tree}} of camel-plc4x has jackson-core and
> jackson-annotations, not jackson-databind.) {{plc4j-scraper}} 0.13.1 declares
> {{jackson-databind}} as a compile dependency. The exclusion came with the
> import of the component (CAMEL-18655, 2022) without a comment or ticket;
> nothing in camel-plc4x needs it. Applications that get {{jackson-databind}}
> from another dependency (for example a Spring Boot web starter) do not see
> the error. The existing test
> {{Plc4XConsumerTest.shouldStartTriggeredScraperWhenTriggerPresent}} does not
> catch it: it stubs {{getTrigger()}} after the consumer was created, so it
> runs the untriggered path.
> h3. Reproduction
> {{Plc4XConsumerStopTest}} (new; {{TriggeredScraperImpl}} and
> {{TriggerCollectorImpl}} replaced with Mockito {{mockConstruction}}): start
> and stop a triggered consumer, the scraper and the collector must be stopped.
> * main: {{NoClassDefFoundError:
> com/fasterxml/jackson/databind/exc/MismatchedInputException}} at start;
> * main with only the dependency fix: {{Wanted but not invoked:
> triggeredScraperImpl.stop()}}.
> h3. Proposed fix
> Keep the scraper and the collector in fields and stop them in {{doStop}};
> create the executor of the one-time read from the {{ExecutorServiceManager}}
> when it is used and shut it down in {{doStop}}; remove the
> {{jackson-databind}} exclusion from {{plc4j-scraper}} (the version is managed
> by Camel's Jackson BOM: 2.22.3, as jackson-core). With the fix the test
> passes, and the module suite passes (18 tests). Note:
> {{TriggeredScraperImpl.stop()}} cancels its tasks but does not shut down the
> scraper's own thread pools (PLC4X library); its idle threads remain.
> Affected: 4.14.x, 4.18.x and main (same code).
> Duplicate check (2026-10-03): JIRA text "plc4x" (10 issues: CAMEL-24171,
> 22491, 20871, 19199, 18861, ...): none about the scraper, the stop or
> jackson-databind. GitHub pull requests "plc4x": none open about the component.
> _Filed with Claude Code on behalf of allthingssecurity._
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