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net/http: reduce mutex contention

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benchmark                           old ns/op    new ns/op    delta
BenchmarkClientServerParallel          155909       154454   -0.93%
BenchmarkClientServerParallel-2         86012        82986   -3.52%
BenchmarkClientServerParallel-4         70211        55168  -21.43%
BenchmarkClientServerParallel-8         80755        47862  -40.73%
BenchmarkClientServerParallel-12        77753        51478  -33.79%
BenchmarkClientServerParallel-16        77920        50278  -35.47%
The benchmark is https://golang.org/cl/6441134
The machine is 2 x 4 HT cores (16 HW threads total).
Fixes #3946.
Now contention moves to net.pollServer.AddFD().

R=bradfitz
CC=bradfitz, dave, dsymonds, gobot, golang-dev, remyoudompheng
https://golang.org/cl/6454142
This commit is contained in:
Dmitriy Vyukov 2012-08-20 13:28:27 +04:00
parent a8357f0160
commit 20f6a8fdaf
2 changed files with 30 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/pkg/net/http/export_test.go
View File

@ -11,8 +11,8 @@ import "time"
func (t *Transport) IdleConnKeysForTesting() (keys []string) {
keys = make([]string, 0)
t.lk.Lock()
defer t.lk.Unlock()
t.idleLk.Lock()
defer t.idleLk.Unlock()
if t.idleConn == nil {
return
}
@ -23,8 +23,8 @@ func (t *Transport) IdleConnKeysForTesting() (keys []string) {
}
func (t *Transport) IdleConnCountForTesting(cacheKey string) int {
t.lk.Lock()
defer t.lk.Unlock()
t.idleLk.Lock()
defer t.idleLk.Unlock()
if t.idleConn == nil {
return 0
}

45
src/pkg/net/http/transport.go
View File

@ -42,8 +42,9 @@ const DefaultMaxIdleConnsPerHost = 2
// https, and http proxies (for either http or https with CONNECT).
// Transport can also cache connections for future re-use.
type Transport struct {
lk sync.Mutex
idleLk sync.Mutex
idleConn map[string][]*persistConn
altLk sync.RWMutex
altProto map[string]RoundTripper // nil or map of URI scheme => RoundTripper
// TODO: tunable on global max cached connections
@ -132,12 +133,12 @@ func (t *Transport) RoundTrip(req *Request) (resp *Response, err error) {
return nil, errors.New("http: nil Request.Header")
}
if req.URL.Scheme != "http" && req.URL.Scheme != "https" {
t.lk.Lock()
t.altLk.RLock()
var rt RoundTripper
if t.altProto != nil {
rt = t.altProto[req.URL.Scheme]
}
t.lk.Unlock()
t.altLk.RUnlock()
if rt == nil {
return nil, &badStringError{"unsupported protocol scheme", req.URL.Scheme}
}
@ -171,8 +172,8 @@ func (t *Transport) RegisterProtocol(scheme string, rt RoundTripper) {
if scheme == "http" || scheme == "https" {
panic("protocol " + scheme + " already registered")
}
t.lk.Lock()
defer t.lk.Unlock()
t.altLk.Lock()
defer t.altLk.Unlock()
if t.altProto == nil {
t.altProto = make(map[string]RoundTripper)
}
@ -187,17 +188,18 @@ func (t *Transport) RegisterProtocol(scheme string, rt RoundTripper) {
// a "keep-alive" state. It does not interrupt any connections currently
// in use.
func (t *Transport) CloseIdleConnections() {
t.lk.Lock()
defer t.lk.Unlock()
if t.idleConn == nil {
t.idleLk.Lock()
m := t.idleConn
t.idleConn = nil
t.idleLk.Unlock()
if m == nil {
return
}
for _, conns := range t.idleConn {
for _, conns := range m {
for _, pconn := range conns {
pconn.close()
}
}
t.idleConn = make(map[string][]*persistConn)
}
//
@ -243,8 +245,6 @@ func (cm *connectMethod) proxyAuth() string {
// If pconn is no longer needed or not in a good state, putIdleConn
// returns false.
func (t *Transport) putIdleConn(pconn *persistConn) bool {
t.lk.Lock()
defer t.lk.Unlock()
if t.DisableKeepAlives || t.MaxIdleConnsPerHost < 0 {
pconn.close()
return false
@ -257,7 +257,12 @@ func (t *Transport) putIdleConn(pconn *persistConn) bool {
if max == 0 {
max = DefaultMaxIdleConnsPerHost
}
t.idleLk.Lock()
if t.idleConn == nil {
t.idleConn = make(map[string][]*persistConn)
}
if len(t.idleConn[key]) >= max {
t.idleLk.Unlock()
pconn.close()
return false
}
@ -267,16 +272,17 @@ func (t *Transport) putIdleConn(pconn *persistConn) bool {
}
}
t.idleConn[key] = append(t.idleConn[key], pconn)
t.idleLk.Unlock()
return true
}
func (t *Transport) getIdleConn(cm *connectMethod) (pconn *persistConn) {
t.lk.Lock()
defer t.lk.Unlock()
if t.idleConn == nil {
t.idleConn = make(map[string][]*persistConn)
}
key := cm.String()
t.idleLk.Lock()
defer t.idleLk.Unlock()
if t.idleConn == nil {
return nil
}
for {
pconns, ok := t.idleConn[key]
if !ok {
@ -513,8 +519,9 @@ type persistConn struct {
func (pc *persistConn) isBroken() bool {
pc.lk.Lock()
defer pc.lk.Unlock()
return pc.broken
b := pc.broken
pc.lk.Unlock()
return b
}
var remoteSideClosedFunc func(error) bool // or nil to use default