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Bug: Dropped update when render phase update happens before suspending #18486

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gaearon opened this issue Apr 4, 2020 · 2 comments · Fixed by #18537
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Bug: Dropped update when render phase update happens before suspending #18486

gaearon opened this issue Apr 4, 2020 · 2 comments · Fixed by #18537
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Component: Suspense Type: Bug

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@gaearon
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gaearon commented Apr 4, 2020

Sandbox: https://codesandbox.io/s/cranky-kapitsa-op3jh

Repro: type "a" and then after a second "b"

Expected: Eventually you'll see "ab" in all fields. Pending "..." indicator goes away.

Actual: You'll keep seeing "a" in low pri field. Pending "..." indicator is stuck.
@gaearon gaearon added Status: Unconfirmed A potential issue that we haven't yet confirmed as a bug Component: Suspense Type: Bug and removed Status: Unconfirmed A potential issue that we haven't yet confirmed as a bug labels Apr 4, 2020
@VakoNonikashvili
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VakoNonikashvili commented Apr 4, 2020 •
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Sandbox: https://codesandbox.io/s/nostalgic-gauss-xrn4o (If I understand problem correctly)

Why didn't you update mirror text with useEffect?

@gaearon
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gaearon commented Apr 4, 2020

Generally saying, render phase updates are better for derived state because you don’t need an extra rendering pass for the whole subtree.

In either case, it doesn’t matter how else I could write it. The problem is that this uncovers a bug in React, and bugs need to be fixed.

gaearon added a commit to gaearon/react that referenced this issue Apr 7, 2020
@gaearon
Add repro case for facebook#18486
8528f6a
@gaearon gaearon mentioned this issue Apr 7, 2020
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acdlite added a commit to acdlite/react that referenced this issue Apr 8, 2020
@acdlite
Add repro case for facebook#18486
384a06f
@acdlite acdlite mentioned this issue Apr 8, 2020
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acdlite pushed a commit to acdlite/react that referenced this issue Apr 8, 2020
@gaearon @acdlite
Add repro case for facebook#18486
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acdlite added a commit that referenced this issue Apr 8, 2020
@acdlite @gaearon
Bugfix: Render phase update causes remaining updates in same componen…
2dddd1e 
…t to be dropped (#18537)

* Bugfix: Render phase update leads to dropped work

Render phase updates should not affect the `fiber.expirationTime` field.
We don't have to set anything on the fiber because we're going to
process the render phase update immediately.

We also shouldn't reset the `expirationTime` field in between render
passes because it represents the remaining work left in the update
queues. During the re-render, the updates that were skipped in the
original pass are not processed again.

I think my original motivation for using this field for render phase
updates was so I didn't have to add another module level variable.

* Add repro case for #18486

Co-authored-by: Dan Abramov <dan.abramov@me.com>
@gaearon gaearon mentioned this issue Apr 18, 2020
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Bugfix: Render phase update causes remaining updates in same component to be dropped acdlite/react
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@gaearon @VakoNonikashvili