Undocumented value replay feature within RetryableOperation presents memory leak

[Hsifnus]

Issue Description

RetryableOperation, a class exclusively used within RetryLink, stores a private array of values that pushes each and every value emitted through the onNext method of RetryableOperation, which itself is called whenever the RetryLink receives a value through next. The purpose of this value array is to replay all previously emitted values to new subscribers to the request observer returned by RetryLink; however, such functionality is not publicly documented in articles relating to RetryLink, nor does the commit adding said functionality (back when the code was part of apollo-link monorepo) mention why this replay feature was added.

This feature becomes problematic when using a periodic, long-running subscription that emits values through next for an indefinite amount of time without completing, which causes the browser to consume more and more memory over time.

A more thorough description of the issue can be found in this community post

Link to Reproduction

subscription backend: https://codesandbox.io/p/devbox/fervent-gwen-kpkwt5?file=%2F.codesandbox%2Ftasks.json%3A5%2C38

frontend subscription with retry link: https://codesandbox.io/p/sandbox/apollo-subscription-with-auth-forked-tzlw6s?file=%2Fsrc%2FAuthors.tsx

Reproduction Steps

• With devtools open, click on Debug! button in the frontend playground to initiate a breakpoint when subscription data arrives
• There should be an entry named RetryableOperation.onNext in the call stack - navigate to this entry
• Set a log point within the this.onNext function definition that logs this.values.length or something similar
• Resume and observe the steadily growing values array

[phryneas]

Could you give the PR release over in #11424 a try and report back if that works for you?

[phryneas]

The fix for this will be in the next Apollo Client 3.9 beta we will release.

[github-actions]

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