heapsnapshot-near-heap-limit creates empty heapdump for docker container

Question

I'm running the node js app inside of Docker container on production

My app has a memory leak and the container fails with OOM.

I'm trying to automatically create a heapdump using --heapsnapshot-near-heap-limit node option. Testing this on my local machine before I can test on production.

I'm emulating a memory leak. However, when memory is full, the node is killed but the heapdump file is empty. Why?

Here is my Dockerfile

# Use the official Node.js image as the base image
FROM node:18-buster-slim

# Set the working directory inside the container
WORKDIR /app

RUN apt-get update && apt-get install -y procps


# Copy the rest of the application files to the container
COPY . .

# Expose the port on which the Node.js app will run (you should use the same port in your Node.js app code)
EXPOSE 3000

# Command to run the Node.js app when the container starts
CMD ["node", "--max-old-space-size=50", "--heapsnapshot-near-heap-limit=3", "app.js"]

Here is my app.js

// app.js
const http = require('http');

const hostname = '0.0.0.0';
const port = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');

  const payload = [];

  function consumeMemory() {
    const data = 'x'.repeat(1000000); // Generate a large string
  
    payload.push(data); // Add the string to the payload array
  
    setTimeout(consumeMemory, 10); // Delay the next iteration by 100 milliseconds
  }
  
  consumeMemory(); // Start consuming memory

  res.end('Hello, World!\n');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

heapsnapshot-near-heap-limit creates empty heapdump for docker container

0 Answers0