Slightly pause on requests to allow most to finish

Currently, every write will result in a 202 (etcd adding a few ms of latency to each request). This forces clients to go into a poll loop and pick a reasonable server poll frequency, which results in 1 + N queries to the server for the single operation and adds unavoidable latency to each request which affects their perception of the service. Add a very slight (25ms by default) delay to wait for requests to finish. For clients doing normal writes this reduces the requests made against the server to 1. For clients on long requests this has no effect. The downside is that http connections are held on to for a longer period in high write loads. The decrease in perceived latency from the kubecfg is significant.

Slightly pause on requests to allow most to finish
1bdeb058 · Clayton Coleman · 2486414c · 1bdeb058 · 1bdeb058 · 1bdeb058
Commit 1bdeb058 authored Jul 29, 2014 by Clayton Coleman
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Showing with 11 additions and 4 deletions

apiserver.go pkg/apiserver/apiserver.go +9 -4

apiserver_test.go pkg/apiserver/apiserver_test.go +1 -0

operation_test.go pkg/apiserver/operation_test.go +1 -0

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--- a/pkg/apiserver/apiserver.go
+++ b/pkg/apiserver/apiserver.go
@@ -59,10 +59,11 @@ func NewNotFoundErr(kind, name string) error {
 //
 // TODO: consider migrating this to go-restful which is a more full-featured version of the same thing.
 type APIServer struct {
-	prefix  string
+	prefix      string
-	storage map[string]RESTStorage
+	storage     map[string]RESTStorage
-	ops     *Operations
+	ops         *Operations
-	mux     *http.ServeMux
+	mux         *http.ServeMux
+	asyncOpWait time.Duration
 }
 // New creates a new APIServer object.
@@ -74,6 +75,8 @@ func New(storage map[string]RESTStorage, prefix string) *APIServer {
 		prefix:  strings.TrimRight(prefix, "/"),
 		ops:     NewOperations(),
 		mux:     http.NewServeMux(),
+		// Delay just long enough to handle most simple write operations
+		asyncOpWait: time.Millisecond * 25,
 	}
 	// Primary API methods
@@ -279,6 +282,8 @@ func (s *APIServer) createOperation(out <-chan interface{}, sync bool, timeout t
 	op := s.ops.NewOperation(out)
 	if sync {
 		op.WaitFor(timeout)
+	} else if s.asyncOpWait != 0 {
+		op.WaitFor(s.asyncOpWait)
 	}
 	return op
 }

--- a/pkg/apiserver/apiserver_test.go
+++ b/pkg/apiserver/apiserver_test.go
@@ -400,6 +400,7 @@ func TestCreate(t *testing.T) {
 	handler := New(map[string]RESTStorage{
 		"foo": simpleStorage,
 	}, "/prefix/version")
+	handler.asyncOpWait = 0
 	server := httptest.NewServer(handler)
 	client := http.Client{}

--- a/pkg/apiserver/operation_test.go
+++ b/pkg/apiserver/operation_test.go
@@ -95,6 +95,7 @@ func TestOpGet(t *testing.T) {
 	handler := New(map[string]RESTStorage{
 		"foo": simpleStorage,
 	}, "/prefix/version")
+	handler.asyncOpWait = 0
 	server := httptest.NewServer(handler)
 	client := http.Client{}