[Fiber] Don't throw away the Error object retaining the owner stack #33976
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sebmarkbage
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Jul 23, 2025
| const fiber: Fiber = (owner: any); | ||
| owner = fiber._debugOwner; | ||
| let debugStack = fiber._debugStack; | ||
| let debugStack: void | null | string | Error = fiber._debugStack; |
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This may still be a string for backwards compat.
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Comparing: edac0dd...9434877 Critical size changesIncludes critical production bundles, as well as any change greater than 2%:
Significant size changesIncludes any change greater than 0.2%: (No significant changes) |
eps1lon
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Jul 24, 2025
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We don't plan to use the Chrome Debugger Protocol for inspecting owner stacks yet so this is not necessary but if ever do, then this would become necessary. So I'll land it preemptively since it should ideally retroactively work as far backwards as possible. |
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…33976) We currently throw away the Error once we've used to the owner stack of a Fiber once. This maybe helps a bit with memory and redoing it but we really don't expect most Fibers to hit this at all. It's not very hot. If we throw away the Error, then we can't use native debugger protocols to inspect the native stack. Instead, we'd have to maintain a url to resource map indefinitely like what Chrome DevTools does to map a url to a resource. Technically it's not even technically correct since the file path might not be reversible and could in theory conflict. DiffTrain build for [4f34cc4](4f34cc4)
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…33976) We currently throw away the Error once we've used to the owner stack of a Fiber once. This maybe helps a bit with memory and redoing it but we really don't expect most Fibers to hit this at all. It's not very hot. If we throw away the Error, then we can't use native debugger protocols to inspect the native stack. Instead, we'd have to maintain a url to resource map indefinitely like what Chrome DevTools does to map a url to a resource. Technically it's not even technically correct since the file path might not be reversible and could in theory conflict. DiffTrain build for [4f34cc4](4f34cc4)
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…acebook#33976) We currently throw away the Error once we've used to the owner stack of a Fiber once. This maybe helps a bit with memory and redoing it but we really don't expect most Fibers to hit this at all. It's not very hot. If we throw away the Error, then we can't use native debugger protocols to inspect the native stack. Instead, we'd have to maintain a url to resource map indefinitely like what Chrome DevTools does to map a url to a resource. Technically it's not even technically correct since the file path might not be reversible and could in theory conflict. DiffTrain build for [4f34cc4](facebook@4f34cc4)
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…acebook#33976) We currently throw away the Error once we've used to the owner stack of a Fiber once. This maybe helps a bit with memory and redoing it but we really don't expect most Fibers to hit this at all. It's not very hot. If we throw away the Error, then we can't use native debugger protocols to inspect the native stack. Instead, we'd have to maintain a url to resource map indefinitely like what Chrome DevTools does to map a url to a resource. Technically it's not even technically correct since the file path might not be reversible and could in theory conflict. DiffTrain build for [4f34cc4](facebook@4f34cc4)
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We currently throw away the Error once we've used to the owner stack of a Fiber once. This maybe helps a bit with memory and redoing it but we really don't expect most Fibers to hit this at all. It's not very hot.
If we throw away the Error, then we can't use native debugger protocols to inspect the native stack. Instead, we'd have to maintain a url to resource map indefinitely like what Chrome DevTools does to map a url to a resource. Technically it's not even technically correct since the file path might not be reversible and could in theory conflict.