[DevTools Bug]: Memory leak when not using the extension

[flaviut]

Website or app

https://example.com

Repro steps

1. use Firefox normally, not opening the browser dev tools at all
2. notice that the browser is getting sluggish due to continual GC, and that Firefox indicates that browser extensions are using 2GiB+
3. disable react dev tools, and observe immediate improvement in memory usage and GC CPU usage

about:memory diff, before and after disabling react dev tools:

extension (pid NNN)
Explicit Allocations

-1,894.73 MB (100.0%) -- explicit
├──-1,684.24 MB (88.89%) -- js-non-window
│  ├──-1,669.75 MB (88.13%) -- zones/zone(0xNNN)
│  │  ├──-1,610.78 MB (85.01%) -- realm([System Principal], shared JSM global)
│  │  │  ├──-1,610.79 MB (85.01%) -- classes
│  │  │  │  ├────-451.06 MB (23.81%) -- class(Map)/objects
│  │  │  │  │    ├──-360.85 MB (19.04%) -- malloc-heap
│  │  │  │  │    │  ├──-360.85 MB (19.04%) ── misc
│  │  │  │  │    │  └────-0.00 MB (00.00%) ── slots
│  │  │  │  │    └───-90.21 MB (04.76%) ── gc-heap
│  │  │  │  ├────-360.87 MB (19.05%) -- class(Function)/objects
│  │  │  │  │    ├──-360.87 MB (19.05%) ── gc-heap
│  │  │  │  │    └────-0.00 MB (00.00%) ── malloc-heap/slots
│  │  │  │  ├────-219.10 MB (11.56%) -- class(Object)/objects
│  │  │  │  │    ├──-167.54 MB (08.84%) ── gc-heap
│  │  │  │  │    └───-51.56 MB (02.72%) -- malloc-heap
│  │  │  │  │        ├──-51.56 MB (02.72%) ── slots
│  │  │  │  │        └───-0.00 MB (00.00%) ── elements/normal
│  │  │  │  ├────-212.20 MB (11.20%) -- class(Set)/objects
│  │  │  │  │    ├──-167.09 MB (08.82%) -- malloc-heap
│  │  │  │  │    │  ├──-167.09 MB (08.82%) ── misc
│  │  │  │  │    │  └─────0.00 MB (-00.00%) ── slots
│  │  │  │  │    └───-45.10 MB (02.38%) ── gc-heap
│  │  │  │  ├────-161.10 MB (08.50%) ── class(Call)/objects/gc-heap
│  │  │  │  ├────-115.99 MB (06.12%) -- class(LexicalEnvironment)/objects
│  │  │  │  │    ├──-115.99 MB (06.12%) ── gc-heap
│  │  │  │  │    └────-0.00 MB (00.00%) ── malloc-heap/slots
│  │  │  │  ├─────-45.34 MB (02.39%) -- class(Array)/objects
│  │  │  │  │     ├──-45.34 MB (02.39%) ── gc-heap
│  │  │  │  │     └───-0.00 MB (00.00%) ── malloc-heap/slots
│  │  │  │  ├─────-45.11 MB (02.38%) ── class(Proxy)/objects/gc-heap
│  │  │  │  └──────-0.01 MB (00.00%) ++ (6 tiny)
│  │  │  └───────0.01 MB (-00.00%) ++ (5 tiny)
│  │  ├─────-40.03 MB (02.11%) -- compartments
│  │  │     ├──-40.03 MB (02.11%) ── cross-compartment-wrapper-tables
│  │  │     └───-0.00 MB (00.00%) ── private-data
│  │  └─────-18.94 MB (01.00%) ++ (19 tiny)
│  └─────-14.49 MB (00.76%) ++ (3 tiny)
├────-137.46 MB (07.25%) -- window-objects
│    ├──-138.79 MB (07.33%) -- top(moz-extension://98c06d52-ba9c-4097-8d95-cfd0565b93d5/_generated_background_page.html, id=NNN)
│    │  ├──-135.99 MB (07.18%) -- active/window(moz-extension://98c06d52-ba9c-4097-8d95-cfd0565b93d5/_generated_background_page.html)
│    │  │  ├──-135.73 MB (07.16%) -- js-realm(moz-extension://98c06d52-ba9c-4097-8d95-cfd0565b93d5/_generated_background_page.html)
│    │  │  │  ├──-135.72 MB (07.16%) -- classes
│    │  │  │  │  ├───-90.48 MB (04.78%) -- class(Function)/objects
│    │  │  │  │  │   ├──-90.48 MB (04.78%) ── gc-heap [-]
│    │  │  │  │  │   └───-0.01 MB (00.00%) ── malloc-heap/slots
│    │  │  │  │  ├───-45.10 MB (02.38%) -- class(Call)/objects
│    │  │  │  │  │   ├──-45.10 MB (02.38%) ── gc-heap [-]
│    │  │  │  │  │   └───-0.00 MB (00.00%) ── malloc-heap/slots
│    │  │  │  │  └────-0.13 MB (00.01%) ++ (4 tiny)
│    │  │  │  └────-0.01 MB (00.00%) ++ sundries
│    │  │  └────-0.26 MB (00.01%) ++ (3 tiny)
│    │  └────-2.80 MB (00.15%) ++ js-zone(0xNNN)
│    └─────1.33 MB (-00.07%) ++ (8 tiny)
├─────-73.74 MB (03.89%) -- heap-overhead
│     ├──-59.05 MB (03.12%) -- bin-unused
│     │  ├──-26.77 MB (01.41%) ── bin-128
│     │  ├──-19.63 MB (01.04%) ── bin-80
│     │  └──-12.65 MB (00.67%) ++ (44 tiny)
│     └──-14.70 MB (00.78%) ++ (2 tiny)
└───────0.71 MB (-00.04%) ++ (7 tiny)

unfortunately, due to https://bugzilla.mozilla.org/show_bug.cgi?id=1766271, I'm unable to get any more detail on what exactly is consuming all this memory.

How often does this bug happen?

Every time

DevTools package (automated)

No response

DevTools version (automated)

No response

Error message (automated)

No response

Error call stack (automated)

No response

Error component stack (automated)

No response

GitHub query string (automated)

No response

[github-actions]

@flaviut: We're sorry you've seen this error. ❤️

It looks like you forgot to specify a valid URL. (This means that we will not be able to reproduce the problem you're reporting.)

Please help us by providing a link to a CodeSandbox (https://codesandbox.io/s/new), a repository on GitHub, or a minimal code example that reproduces the problem. (Screenshots or videos can also be helpful if they help provide context on how to repro the bug.)

Here are some tips for providing a minimal example: https://stackoverflow.com/help/mcve

Issues without repros are automatically closed but we will re-open if you update with repro info.

[github-actions]

Thank you for providing repro steps! Re-opening issue now for triage.

[hoxyq]

Duplicate of #28323