Heap Snapshot exercise

Prepare

Before you try the exercises, please run

npm install

Note, some of the dependencies there are pinned to old versions so that they produce the memory leak you are here to find.

Getting a heap snapshot

• Run npm start
• Open http://localhost:8080
• Now try implementing getting a heap snapshot through a http request and prove a leak exists.
  • Can be done without the heapdump package, with this: https://nodejs.org/dist/latest-v12.x/docs/api/v8.html#v8_v8_writeheapsnapshot_filename

Finding a real issue

Now let's look at a real case of a memory leak. Still a pretty naive one, but one that at least looks realistically.

• Run npm run real
• Open http://localhost:8080
• Get two heap snapshots
• Find the leak, trace it to a properly named object that you can find, locate the code responsible for leaking (or at least the file).

Spoilers

If you're ready to give up, try again and then look at spoilers.txt