perf: remove expensive reflection from xDS hot path#14934
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Replaces the reflection-based implementation of proxycfg's ConfigSnapshot.Clone with code generated by deep-copy. While load testing server-based xDS (for consul-dataplane) we discovered this method is extremely expensive. The ConfigSnapshot struct, directly or indirectly, contains a copy of many of the structs in the agent/structs package, which creates a large graph for copystructure.Copy to traverse at runtime, on every proxy reconfiguration.
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rboyer
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| // DeepCopy generates a deep copy of *PeeringTrustBundle |
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Shouldn't protobufs use proto.Clone instead?
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Maybe, yeah. Although it'd be a bit of a shame to introduce reflection (or at least protobuf's reflection thing) when this type doesn't use any fancy protobuf features.
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Backport of #14934 to 1.13 release series. Replaces the reflection-based implementation of proxycfg's ConfigSnapshot.Clone with code generated by deep-copy.
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This was referenced May 26, 2023
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Description
Replaces the reflection-based implementation of proxycfg's
ConfigSnapshot.Clonewith code generated by deep-copy.While load testing server-based xDS (for consul-dataplane) we discovered this method is extremely expensive.
The
ConfigSnapshotstruct, directly or indirectly, contains a copy of many of the structs in theagent/structspackage, which creates a large graph forcopystructure.Copyto traverse at runtime, on every proxy reconfiguration. This is particularly a problem when updating "global" resources such as wildcard intentions orproxy-defaultswhich triggers a thundering herd of updates (and in our tests caused Raft leadership instability).Testing & Reproduction steps
We test the completeness of
Cloneby using gofuzz to construct a "full" snapshot, cloning it, and then comparing the clone to the original.The Envoy integration tests should also catch any regressions.