Node 16 Memory leak

[odeadglaz]

We are currently using (and loving) this package over our current production applications while we using Node14.

As part of our tech upgrades, we are moving towards Node16 and while we tested our codebase with the new node version, we discovered while monitoring to pods that we huge memo leak.

I tried reproducing the issue using the heapdump script of this package and I got this following results:

-- Node 14 --

• require

• importFresh

-- Node 16 --

• require

• importFresh

It seems that there is a notable difference between two, I might have missed something tho has anybody else had experienced that?

Appreciated, cheers 🎉

[sindresorhus]

Since the memory leak occurs after upgrading Node.js, it's most likely a Node.js bug.

[sindresorhus]

Would you be able to try this branch and see if it improves the situation? https://github.com/sindresorhus/import-fresh/tree/memory-leak

[odeadglaz]

Since the memory leak occurs after upgrading Node.js, it's most likely a Node.js bug.

Yea it could very be, I wasn't able to determine it.

Would you be able to try this branch and see if it improves the situation? https://github.com/sindresorhus/import-fresh/tree/memory-leak

Sure, I'll give it a shot and would update, thanks for the fast response 🙏

[odeadglaz]

So i gave it a shot, I got same results sadly, While inspecting the memory profiler I can see that the modules are kept in memory and not garbage collected due to some reference pointing them which I didn't quite understand, altho the require.cache seems clean (as it should) from any reference to that module being freshly imported.

This acts completely different in Node 14, where the module is being properly garbage collected and it only keeps 1 reference.

[odeadglaz]

So I've done a bit more tracing and it seems to be related to this commit.

For some reason, vm keeps reference to the deleted module via importModuleDynamically which causes the leak.

So it most definitely relates to node 👌

[odeadglaz]

It seems it was already reported as Node issue, once it resolved I think it should work as expected once again