feat(gatsby-core-utils): add fetch mutex for PQR #33161
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gatsbot
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the
status: triage needed
wardpeet
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gatsby 4
topic: data
vladar
reviewed
Sep 14, 2021
| if (entry.status === `complete`) { | ||
| cb(entry.result) | ||
| } else { | ||
| setTimeout(() => { | ||
| pollUntilComplete(cache, url, buildId, cb) | ||
| // Magic number | ||
| }, 500) | ||
| } |
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What happens if a worker starts polling but then the "main" worker fails (i.e. requestRemoteNode throws)? I don't see how it can exist from this function in this case. Can we have a test case for it as it is a typical scenario?
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We keep on hanging
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Depends on how folks use it. If it happens in custom resolver - the corresponding field can just return null (graphql allows partial errors for nullable fields)
vladar
approved these changes
Sep 14, 2021
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Description
When multiple workers fetch the same file we end up with multiple requests to that file. We write to a seperate tmp file but the end result writes (fs.move) to the same file.
This can lead to corrupt files if other parts of the application are resolving it. This PR creates some hacky mutex implementation to make it only write once. It's still possible to write multiple tmp files.
As an adittion I took the inFlight cache from #30391 and implemented it as well to do less polling.