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https://issues.apache.org/jira/browse/CAMEL-23945?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Federico Mariani updated CAMEL-23945:
-------------------------------------
Attachment: LangChain4jAgentFactoryConcurrencyTest.java
> camel-langchain4j-agent: producer race on shared agent field in agentFactory
> mode (fix needed on camel-4.18.x)
> --------------------------------------------------------------------------------------------------------------
>
> Key: CAMEL-23945
> URL: https://issues.apache.org/jira/browse/CAMEL-23945
> Project: Camel
> Issue Type: Bug
> Components: camel-langchain4j-agent
> Affects Versions: 4.15.0, 4.18.0, 4.20.0
> Reporter: Federico Mariani
> Priority: Major
> Attachments: LangChain4jAgentFactoryConcurrencyTest.java
>
>
> On 4.15.0 through 4.20.x (and the current {{camel-4.18.x}} branch),
> {{LangChain4jAgentProducer.process()}} writes the agent resolved by the
> {{AgentFactory}} to a *shared instance field* on every exchange and then
> re-reads that field twice:
> {code:java}
> if (agentFactory != null) {
> agent = agentFactory.createAgent(exchange); // field write per exchange
> }
> AiAgentBody<?> aiAgentBody = agent.processBody(messagePayload, exchange); //
> field re-read
> ...
> String response = agent.chat(aiAgentBody, toolProvider); //
> field re-read again
> {code}
> A producer is a singleton per endpoint and {{process()}} must be thread-safe.
> With two concurrent exchanges selecting different agents (e.g. a multi-agent
> {{AgentFactory}} dispatching by header), one thread's write can land between
> another thread's write and reads: the message is processed by the *wrong
> agent* (wrong model, system prompt, guardrails and chat memory — the
> conversation turn is persisted into the wrong agent's memory store). Because
> there are two independent field reads, a single exchange can even
> {{processBody}} with one agent and {{chat}} with another. The window is tiny
> so it does not reproduce in demos, but under sustained concurrent load it is
> statistically inevitable.
> *Status on main*: fixed incidentally by CAMEL-23697 (commit {{03d8361bbb74}},
> 4.21.0), which replaced the pattern with a local read: {{Agent agent =
> agentFactory != null ? agentFactory.createAgent(exchange) : this.agent;}} —
> so 4.21.0+ is not affected.
> *Requested fix*: backport the local-variable pattern (one line) to the
> {{camel-4.18.x}} LTS branch. Introduced by CAMEL-22397 (commit
> {{91ad52d80fb0}}, first released in 4.15.0).
> Attached reproducer {{LangChain4jAgentFactoryConcurrencyTest}} compiles
> against *camel-4.18.x* (not main, where the API changed with the fix): it
> makes the race deterministic by blocking agent A inside {{processBody()}} —
> between the producer's field write and its {{chat()}} field re-read — while a
> second exchange selects agent B. The exchange that asked for agent A is
> answered by agent B.
> _This issue was drafted by Claude Code on behalf of Federico Mariani._
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