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rlp: use atomic.Value for type cache (#22902)

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All encoding/decoding operations read the type cache to find the
writer/decoder function responsible for a type. When analyzing CPU
profiles of geth during sync, I found that the use of sync.RWMutex in
cache lookups appears in the profiles. It seems we are running into
CPU cache contention problems when package rlp is heavily used
on all CPU cores during sync.

This change makes it use atomic.Value + a writer lock instead of
sync.RWMutex. In the common case where the typeinfo entry is present in
the cache, we simply fetch the map and lookup the type.
This commit is contained in:
Felix Lange
2021-05-22 13:34:29 +02:00
committed by GitHub
parent 59f259b058
commit 0d076d92db
4 changed files with 95 additions and 30 deletions
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4
rlp/encode.go
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@ -517,7 +517,7 @@ func writeInterface(val reflect.Value, w *encbuf) error {
}
func makeSliceWriter(typ reflect.Type, ts tags) (writer, error) {
etypeinfo := cachedTypeInfo1(typ.Elem(), tags{})
etypeinfo := theTC.infoWhileGenerating(typ.Elem(), tags{})
if etypeinfo.writerErr != nil {
return nil, etypeinfo.writerErr
}
@ -585,7 +585,7 @@ func makeStructWriter(typ reflect.Type) (writer, error) {
}
func makePtrWriter(typ reflect.Type, ts tags) (writer, error) {
etypeinfo := cachedTypeInfo1(typ.Elem(), tags{})
etypeinfo := theTC.infoWhileGenerating(typ.Elem(), tags{})
if etypeinfo.writerErr != nil {
return nil, etypeinfo.writerErr
}