Set a floor of 1.5s for threshold to switch Os (livepeer#2837)

* Set a floor of 1.5s for threshold to switch Os

* Update tests to account for new minimum timeout

* Update changelog

CHANGELOG_PENDING.md

@@ -9,6 +9,7 @@
 #### General
 
 #### Broadcaster
+- \#2837 Set a floor of 1.5s for accepted Orchestrator response times, regardless of segment length (@thomshutt) 
 
 #### Orchestrator
 

server/broadcast.go

@@ -238,6 +238,12 @@ func selectSession(ctx context.Context, sessions []*BroadcastSession, exclude []
 			// durMult can be tuned by the caller to tighten/relax the maximum in flight time for the oldest segment
 			maxTimeInFlight := time.Duration(durMult) * oldestSegInFlight.segDur
 
+			// We're more lenient for segments <= 1s in length, since we've found the overheads to make this quite an aggressive target
+			// to consistently meet, so instead set a floor of 1.5s
+			if maxTimeInFlight <= 1*time.Second {
+				maxTimeInFlight = 1500 * time.Millisecond
+			}
+
 			if timeInFlight < maxTimeInFlight {
 				clog.PublicInfof(ctx,
 					"Selected orchestrator reason=%v",

server/broadcast_test.go

@@ -453,15 +453,15 @@ func TestSelectSession_MultipleInFlight2(t *testing.T) {
 }
 
 func TestSelectSession_NoSegsInFlight(t *testing.T) {
-	assert := assert.New(t)
+	assert := require.New(t)
 	ctx := context.Background()
 
 	sess := &BroadcastSession{}
 	sessList := []*BroadcastSession{sess}
 
 	// Session has segs in flight
 	sess.SegsInFlight = []SegFlightMetadata{
-		{startTime: time.Now().Add(time.Duration(-1) * time.Second), segDur: 1 * time.Second},
+		{startTime: time.Now().Add(time.Duration(-2) * time.Second), segDur: 1 * time.Second},
 	}
 	s := selectSession(ctx, sessList, nil, 1)
 	assert.Nil(s)

server/sessionpool_test.go

@@ -376,7 +376,7 @@ func TestSelectSession_MultipleInFlight(t *testing.T) {
 	assert.Equal(expectedSess0.OrchestratorInfo, sess0.OrchestratorInfo)
 	assert.Len(pool.lastSess[0].SegsInFlight, 1)
 
-	time.Sleep(110 * time.Millisecond)
+	time.Sleep(1600 * time.Millisecond)
 
 	sess1 = sendSegStub()
 	assert.Equal(pool.lastSess[0], sess1)
@@ -396,7 +396,7 @@ func TestSelectSession_MultipleInFlight(t *testing.T) {
 	assert.Equal(expectedSess1.OrchestratorInfo, sess0.OrchestratorInfo)
 	assert.Len(pool.lastSess[0].SegsInFlight, 1)
 
-	time.Sleep(110 * time.Millisecond)
+	time.Sleep(1000 * time.Millisecond)
 
 	sess1 = sendSegStub()
 	assert.Equal(pool.lastSess[0], sess1)
@@ -417,7 +417,7 @@ func TestSelectSession_MultipleInFlight(t *testing.T) {
 	assert.Equal(expectedSess1.OrchestratorInfo, sess0.OrchestratorInfo)
 	assert.Len(pool.lastSess[0].SegsInFlight, 1)
 
-	time.Sleep(210 * time.Millisecond)
+	time.Sleep(1600 * time.Millisecond)
 
 	sess1 = sendSegStub()
 	assert.Nil(sess1)
@@ -504,14 +504,14 @@ func TestSelectSessionMoreThanOne(t *testing.T) {
 	assert.Len(pool.sessList(), 0)
 	assert.Len(sessions[0].SegsInFlight, 1)
 	assert.Len(pool.lastSess[0].SegsInFlight, 1)
-	time.Sleep(100 * time.Millisecond)
+	time.Sleep(800 * time.Millisecond)
 	sessions2 := sendSegStub(3)
 	assert.Len(sessions2, 3)
 	assert.Len(pool.sessList(), 0)
 	assert.Len(sessions2[0].SegsInFlight, 2)
 	assert.Len(pool.lastSess[1].SegsInFlight, 2)
 	assert.Equal(sessions, sessions2)
-	time.Sleep(100 * time.Millisecond)
+	time.Sleep(800 * time.Millisecond)
 	sessions3 := sendSegStub(3)
 	assert.Len(sessions3, 0)
 	assert.Len(sessions2[0].SegsInFlight, 2)