structured-merge-diff
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kubernetes-sigs
reconsider use of json-iterator / reflect2
The approach taken by json-iterator and its reflect library is not long-term stable (it pins to internal details of the stdlib reflect package), and requires maintenance per go release, which does not appear to be sustainable https://github.com/golang/go/issues/48238#issuecomment-917000973
Minimum versions to work with go1.18+ are:
- github.com/json-iterator/go v1.1.12
- github.com/modern-go/reflect2 v1.0.2
In addition to the maintenance aspect, it is hard to reason about the safety of the implementation (https://github.com/golang/go/issues/48238#issuecomment-916331048)
I'm exploring what it would look like to use the stdlib json decoder as a base and add in the features we rely on (case-sensitive keys, preservation of ints/floats, etc) in https://github.com/kubernetes/kubernetes/pull/105030
I would encourage this project to consider the long-term sustainability/safety of the json-iterator dependency as well.
I think the uses here are benchmarked and it should be easy to tell if swapping out json-iterator causes a regression.
https://github.com/kubernetes/kubernetes/pull/105030 is now merged and this is on the short-list of things in k/k that still use json-iterator
it looks like this uses really specialized serializing capabilities provided by json-iterator... not sure swapping will be easy
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@k8s-triage-robot: Closing this issue.
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@liggitt: Reopened this issue.
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with the release of go1.18, the json-iterator / reflect2 versions this lib uses as of today will not work with current versions of go
When json-next-experimental becomes non-experimental, we could consider this. I don't think we need to solve this right now though.
I would still consider use of json-iterator a risk due to its history with correctness issues and reliance on specific internal implementations of the go runtime
There is more trouble that reflect2 brings. It inhibits the dead code elimination in the golang compiler.
Golang 1.22 has learned to keep the DCE enabled when the usages of MethodByName() are limited to MethodByName(compile-time constant). Usages of MethodByName() in github.com/kubernetes/kubernetes are DCE-friendly already, and various dependencies like google.golang.org/protobuf and github.com/kubernetes/kube-openapi were fixed to be DCE-friendly over several last months.
reflect2 plays tricks that confuse golang and disable the DCE. Everything that depends on structured-merge-diff, even indirectly, compiles with the DCE disabled because of reflect2.
@liggitt I created a first working version: https://github.com/kubernetes-sigs/structured-merge-diff/pull/257
