如何以编程方式知道 NodeJS 应用程序何时用完 memory

Question

How can I know when my application is running out of memory.

For me, I'm doing some video transcoding on the server and sometimes it leads to out of memory errors.

So, I wish to know when the application is running out of memory so I can immediately kill the Video Transcoder.

Thank you.

Answer 1

You can see how much memory is being used with the built-in process module.

const process = require("process");

The process module has a method calledmemoryUsage , which shows info on the memory usage in Node.js.

console.log(process.memoryUsage());

When you run the code, you should see an object with all of the information needed for memory usage!

$ node index.js
{
  rss: 4935680,
  heapTotal: 1826816,
  heapUsed: 650472,
  external: 49879,
  arrayBuffers: 9386
}

---

Here is some insight on each property.

• rss - (Resident Set Size) Amount of space occupied in the main memory device.
• heapTotal - The total amount of memory in the V8 engine.
• heapUsed - The amount of memory used by the V8 engine.
• external - The memory usage of C++ objects bound to JavaScript objects (managed by V8).
• arrayBuffers - The memory allocated for ArrayBuffer s and Buffer s.

---

For your question, you might need to use heapTotal and heapUsed . Depending on the value, you can then shut the service down. For example:

const process = require("process");

const mem = process.memoryUsage();
const MAX_SIZE = 50; // Change the value to what you want

if ((mem.heapUsed / 1000000) >= MAX_SIZE) {
  videoTranscoder.kill(); // Just an example...
}

The division by one million part just converts bytes to megabytes (B to MB).

_{Change the code to what you like - this is just an example.}