mirror/protobuf-go
1
0
Fork 0
mirror of https://github.com/protocolbuffers/protobuf-go.git synced 2025-01-01 11:58:21 +00:00
Code Issues Packages Projects Releases Wiki Activity

internal/impl: avoid inlining fixed coderFieldInfo array

Browse Source 
Any attempt at guessing the size for a fixed coderFieldInfo array
will always get it wrong in some cases, either by under-estimating
or over-estimating the count. The former causes worse caching behavior,
while the latter causes memory waste.

As a middle ground, just pre-allocate a slice of the exact length.
Each element will have memory locality with each other, but not
be guaranteed to have memory locality with the parent coderMessageInfo.

name                            old time/op  new time/op  delta
EmptyMessage/Wire/Marshal-8     43.1ns ±11%  42.6ns ± 8%  -1.32%  (p=0.036 n=50+49)
EmptyMessage/Wire/Unmarshal-8   18.6ns ±10%  18.9ns ±12%    ~     (p=0.054 n=50+50)
EmptyMessage/Wire/Validate-8    15.0ns ± 9%  14.7ns ±10%  -2.44%  (p=0.002 n=50+45)
EmptyMessage/Clone-8             163ns ±20%   149ns ±19%  -8.58%  (p=0.000 n=48+53)
RepeatedInt32/Wire/Marshal-8    4.27µs ±12%  4.24µs ±13%    ~     (p=0.612 n=48+52)
RepeatedInt32/Wire/Unmarshal-8  3.47µs ±14%  3.50µs ±11%    ~     (p=0.217 n=50+53)
RepeatedInt32/Wire/Validate-8   2.12µs ±12%  2.09µs ± 9%    ~     (p=0.121 n=50+51)
RepeatedInt32/Clone-8           3.04µs ±18%  2.98µs ±36%    ~     (p=0.289 n=51+54)
Required/Wire/Marshal-8          281ns ±14%   276ns ±11%    ~     (p=0.059 n=48+55)
Required/Wire/Unmarshal-8        117ns ±14%   118ns ±11%    ~     (p=0.358 n=49+53)
Required/Wire/Validate-8        87.6ns ± 9%  88.0ns ±12%    ~     (p=0.373 n=48+53)
Required/Clone-8                 533ns ±12%   507ns ±15%  -4.71%  (p=0.000 n=49+54)

Change-Id: I4cf3134e424130bee728b7591127e5c80f07e2db
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/232937
Reviewed-by: Damien Neil <dneil@google.com>
This commit is contained in:
Joe Tsai 2020-05-08 00:32:06 -07:00
parent 8525b20428
commit 3034025d28
1 changed files with 2 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
internal/impl/codec_message.go
View File

@ -31,11 +31,6 @@ type coderMessageInfo struct {
needsInitCheck bool
isMessageSet bool
numRequiredFields uint8
// Include space for a number of coderFieldInfos to improve cache locality.
// The number of entries is chosen through a combination of guesswork and
// empirical testing.
coderFieldBuf [32]coderFieldInfo
}
type coderFieldInfo struct {
@ -58,7 +53,7 @@ func (mi *MessageInfo) makeCoderMethods(t reflect.Type, si structInfo) {
mi.coderFields = make(map[protowire.Number]*coderFieldInfo)
fields := mi.Desc.Fields()
preallocFields := mi.coderFieldBuf[:]
preallocFields := make([]coderFieldInfo, fields.Len())
for i := 0; i < fields.Len(); i++ {
fd := fields.Get(i)
@ -87,13 +82,7 @@ func (mi *MessageInfo) makeCoderMethods(t reflect.Type, si structInfo) {
fieldOffset = offsetOf(fs, mi.Exporter)
childMessage, funcs = fieldCoder(fd, ft)
}
var cf *coderFieldInfo
if len(preallocFields) > 0 {
cf = &preallocFields[0]
preallocFields = preallocFields[1:]
} else {
cf = new(coderFieldInfo)
}
cf := &preallocFields[i]
*cf = coderFieldInfo{
num: fd.Number(),
offset: fieldOffset,