Remove two unnecessary memory copies on Any. - #1985
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Two parts of `Any` will construct a `Data` unnecessarily, triggering a memory copy. One is used to serialize a JSON body (stored as an Array of UInt8) into a Data, by way of an intermediate Array. This intermediate Array is not necessary: we should go directly to the final Data. The second is accessing an already serialized value, which already has a Data in hand, and calls `Data(thatData)`. This initializer looks innocuous, but `Data` does not actually have a special-case for this, so this ends up hitting the initializer that takes a `Sequence`, so does a bulk copy operation instead. This patch changes both of these to remove extra memory copies when using Any.
FranzBusch
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Feb 20, 2026
thomasvl
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Feb 20, 2026
thomasvl
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thomasvl
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Nice find. Happen to just notice it or did this get caught in some performance case?
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It got caught by an internal team who ended up spending 8% of their runtime in one of these copies 😱 |
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Wow. Should we cut a release for the fix? |
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Sometime soon probably, yeah. Right now they can prototype using |
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Two parts of
Anywill construct aDataunnecessarily, triggering a memory copy. One is used to serialize a JSON body (stored as an Array of UInt8) into a Data, by way of an intermediate Array. This intermediate Array is not necessary: we should go directly to the final Data.The second is accessing an already serialized value, which already has a Data in hand, and calls
Data(thatData). This initializer looks innocuous, butDatadoes not actually have a special-case for this, so this ends up hitting the initializer that takes aSequence, so does a bulk copy operation instead.This patch changes both of these to remove extra memory copies when using Any.