optimize gc and add tests for GC

Author: xtaci

aio_test.go

@@ -971,3 +971,76 @@ func BenchmarkContextSwitch(b *testing.B) {
 	}
 	close(die)
 }
+
+func TestGC(t *testing.T) {
+	par := 1024
+	msgsize := 65536
+	t.Log("testing GC:", par, "connections")
+	ln := echoServer(t, msgsize)
+	defer ln.Close()
+
+	w, err := NewWatcher()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer w.Close()
+
+	for i := 0; i < par; i++ {
+		go func() {
+			data := make([]byte, msgsize)
+			conn, err := net.Dial("tcp", ln.Addr().String())
+			if err != nil {
+				log.Fatal(err)
+			}
+
+			// send
+			err = w.Write(nil, conn, data)
+			if err != nil {
+				log.Fatal(err)
+			}
+
+			conn = nil
+		}()
+	}
+
+	count := 0
+LOOP:
+	for {
+		results, err := w.WaitIO()
+		if err != nil {
+			t.Fatal("waitio:", err)
+			return
+		}
+
+		for _, res := range results {
+			switch res.Operation {
+			case OpWrite:
+			case OpRead:
+			}
+			res.Conn = nil
+
+			count++
+			if count >= par {
+				break LOOP
+			}
+		}
+	}
+
+	found, closed := w.GetGC()
+	t.Logf("GC found:%d closed:%d", found, closed)
+	<-time.After(2 * time.Second)
+	runtime.GC()
+
+	found, closed = w.GetGC()
+	t.Logf("GC found:%d closed:%d", found, closed)
+	<-time.After(2 * time.Second)
+	runtime.GC()
+
+	found, closed = w.GetGC()
+	t.Logf("GC found:%d closed:%d", found, closed)
+	<-time.After(2 * time.Second)
+	runtime.GC()
+
+	found, closed = w.GetGC()
+	t.Logf("GC found:%d closed:%d", found, closed)
+}

watcher.go

@@ -96,9 +96,11 @@ type watcher struct {
 	timer      *time.Timer     // Timer for handling timeouts
 
 	// Garbage collection
-	gc       []net.Conn    // List of connections to be garbage collected
+	gc       []uintptr     // List of connections to be garbage collected
 	gcMutex  sync.Mutex    // Mutex to synchronize access to the gc list
 	gcNotify chan struct{} // Channel to notify the GC processor
+	gcFound  uint32        // number of net.Conn objects found unreachable by runtime
+	gcClosed uint32        // record number of objects closed successfully
 
 	// Shutdown and cleanup
 	die     chan struct{} // Channel for signaling shutdown
@@ -571,19 +573,8 @@ func (w *watcher) loop() {
 					break
 				}
 			}
-
-		case <-w.gcNotify: // GC recycled net.Conn
-			w.gcMutex.Lock()
-			for i, c := range w.gc {
-				ptr := reflect.ValueOf(c).Pointer()
-				if ident, ok := w.connIdents[ptr]; ok {
-					w.releaseConn(ident)
-				}
-				w.gc[i] = nil
-			}
-			w.gc = w.gc[:0]
-			w.gcMutex.Unlock()
-
+		case <-w.gcNotify:
+			w.handleGC()
 		case cpuid := <-w.chCPUID:
 			setAffinity(cpuid)
 
@@ -593,6 +584,22 @@ func (w *watcher) loop() {
 	}
 }
 
+// handleGC processes the garbage collection of net.Conn objects.
+func (w *watcher) handleGC() {
+	runtime.GC()
+	w.gcMutex.Lock()
+	if len(w.gc) > 0 {
+		for _, ptr := range w.gc {
+			if ident, ok := w.connIdents[ptr]; ok {
+				w.releaseConn(ident)
+			}
+		}
+		w.gcClosed += uint32(len(w.gc))
+		w.gc = w.gc[:0]
+	}
+	w.gcMutex.Unlock()
+}
+
 // handlePending processes new requests, acting as a reception desk.
 func (w *watcher) handlePending(pending []*aiocb) {
 PENDING:
@@ -641,7 +648,9 @@ PENDING:
 				// if not it will never be GC-ed.
 				runtime.SetFinalizer(pcb.conn, func(c net.Conn) {
 					w.gcMutex.Lock()
-					w.gc = append(w.gc, c)
+					ptr := reflect.ValueOf(c).Pointer()
+					w.gc = append(w.gc, ptr)
+					w.gcFound++
 					w.gcMutex.Unlock()
 
 					// notify gc processor
@@ -741,3 +750,10 @@ func (w *watcher) handleEvents(events pollerEvents) {
 		}
 	}
 }
+
+// read gcFound & gcClosed
+func (w *watcher) GetGC() (found uint32, closed uint32) {
+	w.gcMutex.Lock()
+	defer w.gcMutex.Unlock()
+	return w.gcFound, w.gcClosed
+}