all: use timer instead of time.After in loops, to avoid memleaks (ethereum#29241)

time.After is equivalent to NewTimer(d).C, and does not call Stop if the timer is no longer needed. This can cause memory leaks. This change changes many such occations to use NewTimer instead, and calling Stop once the timer is no longer needed.

Author: songzhibin97

core/bloombits/matcher.go

@@ -596,6 +596,9 @@ func (s *MatcherSession) deliverSections(bit uint, sections []uint64, bitsets []
 // of the session, any request in-flight need to be responded to! Empty responses
 // are fine though in that case.
 func (s *MatcherSession) Multiplex(batch int, wait time.Duration, mux chan chan *Retrieval) {
+	waitTimer := time.NewTimer(wait)
+	defer waitTimer.Stop()
+
 	for {
 		// Allocate a new bloom bit index to retrieve data for, stopping when done
 		bit, ok := s.allocateRetrieval()
@@ -604,14 +607,15 @@ func (s *MatcherSession) Multiplex(batch int, wait time.Duration, mux chan chan
 		}
 		// Bit allocated, throttle a bit if we're below our batch limit
 		if s.pendingSections(bit) < batch {
+			waitTimer.Reset(wait)
 			select {
 			case <-s.quit:
 				// Session terminating, we can't meaningfully service, abort
 				s.allocateSections(bit, 0)
 				s.deliverSections(bit, []uint64{}, [][]byte{})
 				return
 
-			case <-time.After(wait):
+			case <-waitTimer.C:
 				// Throttling up, fetch whatever is available
 			}
 		}

eth/downloader/beaconsync.go

@@ -289,6 +289,9 @@ func (d *Downloader) fetchBeaconHeaders(from uint64) error {
 		localHeaders = d.readHeaderRange(tail, int(count))
 		log.Warn("Retrieved beacon headers from local", "from", from, "count", count)
 	}
+	fsHeaderContCheckTimer := time.NewTimer(fsHeaderContCheck)
+	defer fsHeaderContCheckTimer.Stop()
+
 	for {
 		// Some beacon headers might have appeared since the last cycle, make
 		// sure we're always syncing to all available ones
@@ -381,8 +384,9 @@ func (d *Downloader) fetchBeaconHeaders(from uint64) error {
 		}
 		// State sync still going, wait a bit for new headers and retry
 		log.Trace("Pivot not yet committed, waiting...")
+		fsHeaderContCheckTimer.Reset(fsHeaderContCheck)
 		select {
-		case <-time.After(fsHeaderContCheck):
+		case <-fsHeaderContCheckTimer.C:
 		case <-d.cancelCh:
 			return errCanceled
 		}

eth/downloader/downloader.go

@@ -1276,7 +1276,10 @@ func (d *Downloader) processHeaders(origin uint64, td, ttd *big.Int, beaconMode
 	var (
 		mode       = d.getMode()
 		gotHeaders = false // Wait for batches of headers to process
+		timer      = time.NewTimer(time.Second)
 	)
+	defer timer.Stop()
+
 	for {
 		select {
 		case <-d.cancelCh:
@@ -1397,10 +1400,11 @@ func (d *Downloader) processHeaders(origin uint64, td, ttd *big.Int, beaconMode
 				if mode == FullSync || mode == SnapSync {
 					// If we've reached the allowed number of pending headers, stall a bit
 					for d.queue.PendingBodies() >= maxQueuedHeaders || d.queue.PendingReceipts() >= maxQueuedHeaders {
+						timer.Reset(time.Second)
 						select {
 						case <-d.cancelCh:
 							return errCanceled
-						case <-time.After(time.Second):
+						case <-timer.C:
 						}
 					}
 					// Otherwise insert the headers for content retrieval
@@ -1567,7 +1571,10 @@ func (d *Downloader) processSnapSyncContent() error {
 	var (
 		oldPivot *fetchResult   // Locked in pivot block, might change eventually
 		oldTail  []*fetchResult // Downloaded content after the pivot
+		timer    = time.NewTimer(time.Second)
 	)
+	defer timer.Stop()
+
 	for {
 		// Wait for the next batch of downloaded data to be available. If we have
 		// not yet reached the pivot point, wait blockingly as there's no need to
@@ -1650,6 +1657,7 @@ func (d *Downloader) processSnapSyncContent() error {
 				oldPivot = P
 			}
 			// Wait for completion, occasionally checking for pivot staleness
+			timer.Reset(time.Second)
 			select {
 			case <-sync.done:
 				if sync.err != nil {
@@ -1660,7 +1668,7 @@ func (d *Downloader) processSnapSyncContent() error {
 				}
 				oldPivot = nil
 
-			case <-time.After(time.Second):
+			case <-timer.C:
 				oldTail = afterP
 				continue
 			}

ethstats/ethstats.go

@@ -544,10 +544,13 @@ func (s *Service) reportLatency(conn *connWrapper) error {
 		return err
 	}
 	// Wait for the pong request to arrive back
+	timer := time.NewTimer(5 * time.Second)
+	defer timer.Stop()
+
 	select {
 	case <-s.pongCh:
 		// Pong delivered, report the latency
-	case <-time.After(5 * time.Second):
+	case <-timer.C:
 		// Ping timeout, abort
 		return errors.New("ping timed out")
 	}

p2p/simulations/adapters/exec.go

@@ -303,10 +303,13 @@ func (n *ExecNode) Stop() error {
 	go func() {
 		waitErr <- n.Cmd.Wait()
 	}()
+	timer := time.NewTimer(5 * time.Second)
+	defer timer.Stop()
+
 	select {
 	case err := <-waitErr:
 		return err
-	case <-time.After(5 * time.Second):
+	case <-timer.C:
 		return n.Cmd.Process.Kill()
 	}
 }

p2p/simulations/mocker.go

@@ -65,8 +65,13 @@ func startStop(net *Network, quit chan struct{}, nodeCount int) {
 	if err != nil {
 		panic("Could not startup node network for mocker")
 	}
-	tick := time.NewTicker(10 * time.Second)
+	var (
+		tick  = time.NewTicker(10 * time.Second)
+		timer = time.NewTimer(3 * time.Second)
+	)
 	defer tick.Stop()
+	defer timer.Stop()
+
 	for {
 		select {
 		case <-quit:
@@ -80,11 +85,12 @@ func startStop(net *Network, quit chan struct{}, nodeCount int) {
 				return
 			}
 
+			timer.Reset(3 * time.Second)
 			select {
 			case <-quit:
 				log.Info("Terminating simulation loop")
 				return
-			case <-time.After(3 * time.Second):
+			case <-timer.C:
 			}
 
 			log.Debug("starting node", "id", id)

p2p/simulations/network.go

@@ -1028,11 +1028,14 @@ func (net *Network) Load(snap *Snapshot) error {
 		}
 	}
 
+	timeout := time.NewTimer(snapshotLoadTimeout)
+	defer timeout.Stop()
+
 	select {
 	// Wait until all connections from the snapshot are established.
 	case <-allConnected:
 	// Make sure that we do not wait forever.
-	case <-time.After(snapshotLoadTimeout):
+	case <-timeout.C:
 		return errors.New("snapshot connections not established")
 	}
 	return nil