Tracing

Similar to the Python langchain package, JS langchain also supports tracing.

You can view an overview of tracing here. To spin up the tracing backend, run docker compose up (or docker-compose up if on using an older version of docker) in the langchain directory. You can also use the langchain-server command if you have the python langchain package installed.

Here's an example of how to use tracing in langchain.js. All that needs to be done is setting the LANGCHAIN_TRACING environment variable to true.

import { OpenAI } from "langchain/llms/openai";
import { initializeAgentExecutorWithOptions } from "langchain/agents";
import { SerpAPI } from "langchain/tools";
import { Calculator } from "langchain/tools/calculator";
import process from "process";

export const run = async () => {
  process.env.LANGCHAIN_TRACING = "true";
  const model = new OpenAI({ temperature: 0 });
  const tools = [
    new SerpAPI(process.env.SERPAPI_API_KEY, {
      location: "Austin,Texas,United States",
      hl: "en",
      gl: "us",
    }),
    new Calculator(),
  ];

  const executor = await initializeAgentExecutorWithOptions(tools, model, {
    agentType: "zero-shot-react-description",
    verbose: true,
  });
  console.log("Loaded agent.");

  const input = `Who is Olivia Wilde's boyfriend? What is his current age raised to the 0.23 power?`;

  console.log(`Executing with input "${input}"...`);

  const result = await executor.call({ input });

  console.log(`Got output ${result.output}`);
};

Concurrency

Tracing works with concurrency out of the box.

import { OpenAI } from "langchain/llms/openai";
import { initializeAgentExecutorWithOptions } from "langchain/agents";
import { SerpAPI } from "langchain/tools";
import { Calculator } from "langchain/tools/calculator";
import process from "process";

export const run = async () => {
  process.env.LANGCHAIN_TRACING = "true";
  const model = new OpenAI({ temperature: 0 });
  const tools = [
    new SerpAPI(process.env.SERPAPI_API_KEY, {
      location: "Austin,Texas,United States",
      hl: "en",
      gl: "us",
    }),
    new Calculator(),
  ];

  const executor = await initializeAgentExecutorWithOptions(tools, model, {
    agentType: "zero-shot-react-description",
    verbose: true,
  });

  console.log("Loaded agent.");

  const input = `Who is Olivia Wilde's boyfriend? What is his current age raised to the 0.23 power?`;

  console.log(`Executing with input "${input}"...`);

  // This will result in a lot of errors, because the shared Tracer is not concurrency-safe.
  const [resultA, resultB, resultC] = await Promise.all([
    executor.call({ input }),
    executor.call({ input }),
    executor.call({ input }),
  ]);

  console.log(`Got output ${resultA.output} ${resultA.__run.runId}`);
  console.log(`Got output ${resultB.output} ${resultB.__run.runId}`);
  console.log(`Got output ${resultC.output} ${resultC.__run.runId}`);

  /*
    Got output Harry Styles, Olivia Wilde's boyfriend, is 29 years old and his age raised to the 0.23 power is 2.169459462491557. b8fb98aa-07a5-45bd-b593-e8d7376b05ca
    Got output Harry Styles, Olivia Wilde's boyfriend, is 29 years old and his age raised to the 0.23 power is 2.169459462491557. c8d916d5-ca1d-4702-8dd7-cab5e438578b
    Got output Harry Styles, Olivia Wilde's boyfriend, is 29 years old and his age raised to the 0.23 power is 2.169459462491557. bf5fe04f-ef29-4e55-8ce1-e4aa974f9484
    */
};