Memory leak on SSR after upgrading from 2.x to 3.3.13

Recently decided to upgrade apollo client from 2.6 to 3.3.13. After releasing it to production we saw huge memory usage increase on a server side. Rolling back to the old 2.6 version solved the problem.

Here is what happened in production while switched to 3.3.13 (tried to solve memory leak problem), gave up after 3 days and rolled back to 2.6:

Here is what we saw in the heapdumps (comparison view, filtered objects that were not deleted):

Seems like a lot of “Entry” instances are not garbage collected (deleted 0). Here is a dependency tree, maybe someone can help to see where the problem is:

Any help will be appreciated 🙏

Heapdumps:

• https://drive.google.com/file/d/10DnUSdyXN5q030bbcVXmgNpWWcUeVfy0/view?usp=sharing
• https://drive.google.com/file/d/1a05z2oty1i5foYvBkHK_T6uWdHwdPmw4/view?usp=sharing

Shortly about our setup:

• SSR (Node.js, React, apollo)
• Server side code is bundled with webpack

What we have tried:

• resultCaching:false config for the inmemory cache
• Manuall call client.stop() client.clearStore after each request.
• Removed all readFragment calls.
• Different node.js versions 12.8, 14.16
• Increased max old space size (heap size)
• Downgrade to apollo 3.1.3

Versions

• OS - alpine3.11
• @apollo/client - 3.3.13
• node.js - 14.16.0
• react - 16.8.2
• webpack 4.35.2
• graphql": 15.5.0
• graphql-tag": 2.12.0

[AlexMost]

Tried fetchPolicy: no-cache this one reduces memory and CPU consumption significantly, but memory leak is still present 😢

Currently, we have test setup with apollo3 with mirrored traffic from production, so I can check any hypothesis very quickly, any suggestion or help will be much appreciated!

[matthewnourse]

The problem for us was that the stringifyCanon and stringifyCache globals in object-canon.js grow without bound even when caching is disabled. The fix was to call ApolloClient.clearStore whenever we create the client:

export const getApolloClient = () => {
  const client = new ApolloClient({ /* whatever config you need  here */ });

  return client.clearStore().then(() => client);
}