[Solved] How do you correctly attach a LangChainTracer to an LLMChain to capture trace data? — Ans: Pass the tracer instance to the chain's callbacks parameter during... | LangChain

LangChain - LangSmith Observability

How do you correctly attach a LangChainTracer to an LLMChain to capture trace data?

ASet an environment variable LANGCHAIN_TRACE=true before running the chain

BCall tracer.start() before running the chain and tracer.stop() after

CPass the tracer instance to the chain's callbacks parameter during initialization

DWrap the chain.run() call inside a with tracer: block

Step-by-Step Solution

Solution:

Step 1: Understand how LangChainTracer integrates
LangChainTracer is passed as a callback to the chain to collect trace data.
Step 2: Identify correct usage
Providing the tracer in the callbacks parameter ensures it hooks into chain execution.
Final Answer:
Pass the tracer instance to the chain's callbacks parameter during initialization -> Option C
Quick Check:
Tracer must be registered as a callback [OK]

Quick Trick: Attach tracer via callbacks parameter [OK]

Common Mistakes:

MISTAKES

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