Remove Stateful JSON encoding and decoding #410
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danibachar
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crow,
rlepinski,
khmMouna and
oristanovic
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This PR is in response to this one, converting all instance based usage of encoders/decoder
What do these changes do?
The changes removes the usage of an instance base encoders/decoders
Why are these changes necessary?
While its not documented very well, JSONEncoder/Decoder are a stateful objects, which makes them non-thread safe.
We are using version 17.10.0 and facing exceptions around that code, which made me think its a thread issue.
In anyway spinning a new encoder/decoder is the recommended way and very cheap in resources.
How did you verify these changes?
Testing for thread safety issues is a hard task, as such I could not create a test to reproduce it.
Here is a thread supporting my theory - https://forums.swift.org/t/is-it-ok-to-create-jsondecoder-only-once-in-withthrowingtaskgroup/57260
Verification Screenshots:
Anything else a reviewer should know?
Here is the stack trace at the app level crash
Crashed in non-app Foundation | +0x04e7b0 | String.withUTF8
Foundation | +0x04e798 | String.withUTF8
Foundation | +0x04eb88 | JSONWriter.serializeString
Foundation | +0x04e80c | JSONWriter.serializeJSON
Foundation | +0x04cfd0 | JSONWriter.serializeObject
Foundation | +0x04e910 | JSONWriter.serializeJSON
Foundation | +0x04cfd0 | JSONWriter.serializeObject
Foundation | +0x04e910 | JSONWriter.serializeJSON
Foundation | +0x0d06f8 | JSONEncoder.encode
Foundation | +0x0d0480 | JSONEncoder.encode
MyAppName | +0xf8a454 | ChannelAPIClient.updateChannel (ChannelAPIClient.swift:105) (In App)
Called from libswift_Concurrency | +0x04d760 | swift::runJobInEstablishedExecutorContext