Add some logs for waiting on a channel (#3048)

* Add some logs for waiting on a channel

* Add logging to core package instead

src/core/state.go

@@ -834,11 +834,25 @@ func (state *BuildState) SyncParsePackage(label BuildLabel) *Package {
 		return p
 	}
 	if ch, inserted := state.progress.pendingPackages.AddOrGet(label.packageKey(), make(chan struct{})); !inserted {
-		<-ch
+		waitOnChan(ch, fmt.Sprintf("Still waiting for SyncParsePackage(%v)", label))
 	}
 	return state.Graph.PackageByLabel(label) // Important to check again; it's possible to race against this whole lot.
 }
 
+func waitOnChan[T any](ch chan T, message string) T {
+	start := time.Now()
+	for {
+		select {
+		case v := <-ch:
+			return v
+		case <-time.After(time.Second * 10):
+			{
+				log.Debugf("%v (after %v)", message, time.Since(start))
+			}
+		}
+	}
+}
+
 // WaitForPackage is similar to WaitForBuiltTarget however it waits for the package to be parsed, queuing it for parse
 // if necessary
 func (state *BuildState) WaitForPackage(l, dependent BuildLabel, mode ParseMode) *Package {
@@ -849,13 +863,13 @@ func (state *BuildState) WaitForPackage(l, dependent BuildLabel, mode ParseMode)
 
 	// If something has promised to parse it, wait for them to do so
 	if ch := state.progress.pendingPackages.Get(key); ch != nil {
-		<-ch
+		waitOnChan(ch, fmt.Sprintf("Still waiting for pending package in WaitForPackage(%v, %v, %v)", l, dependent, mode))
 		return state.Graph.PackageByLabel(l)
 	}
 
 	// If something has already queued the package to be parsed, wait for them
 	if ch := state.progress.packageWaits.Get(key); ch != nil {
-		<-ch
+		waitOnChan(ch, fmt.Sprintf("Still waiting for package wait in WaitForPackage(%v, %v, %v)", l, dependent, mode))
 		return state.Graph.PackageByLabel(l)
 	}
 
@@ -876,7 +890,7 @@ func (state *BuildState) WaitForBuiltTarget(l, dependent BuildLabel, mode ParseM
 	// okay, we need to register and wait for this guy.
 	if ch, inserted := state.progress.pendingTargets.AddOrGet(l, make(chan struct{})); !inserted {
 		// Something's already registered for this, get on the train
-		<-ch
+		waitOnChan(ch, fmt.Sprintf("Still waiting on WaitForBuiltTarget(%v, %v, %v)", l, dependent, mode))
 		return state.Graph.Target(l)
 	}
 	if err := state.queueTarget(l, dependent, mode.IsForSubinclude(), mode); err != nil {