print outputs immediately

Author: David Cavazos

.github/workflows/samples-tools/cmd/main.go

@@ -140,7 +140,7 @@ func runAllCmd(configFile string, script string) {
 		fmt.Fprintf(os.Stderr, "❌ error finding packages.\n%v\n", err)
 	}
 
-	maxGoroutines := 32
+	maxGoroutines := 16
 	failed := runAll(packages, script, maxGoroutines)
 
 	fmt.Printf(strings.Repeat("-", 80) + "\n")

.github/workflows/samples-tools/cmd/runAll.go

@@ -25,23 +25,21 @@ import (
 
 // runAll runs all the commands in parallel.
 func runAll(packages []string, script string, maxGoroutines int) int {
-	failures := mapParallel(maxGoroutines, packages, func(pkg string) string {
-		// TODO(dcavazos): measure time spent on each test and print it along the results
-		output, err := exec.Command("bash", script, pkg).CombinedOutput()
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "%v\n❌ FAILED: %v\n%v\n%v\n%v\n\n",
-				strings.Repeat("=", 80),
-				pkg,
-				strings.Repeat("-", 80),
-				err,
-				string(output),
-			)
-			return pkg
-		} else {
-			fmt.Printf("✅ %v\n", pkg)
-		}
-		return ""
-	})
+	failures := make([]string, len(packages))
+	guard := make(chan struct{}, maxGoroutines)
+	for i, pkg := range packages {
+		guard <- struct{}{} // block if channel is filled
+		go func() {
+			output, err := exec.Command("bash", script, pkg).CombinedOutput()
+			if err != nil {
+				printError(os.Stderr, pkg, err, string(output))
+				failures[i] = pkg
+			} else {
+				fmt.Printf("✅ %v\n", pkg)
+			}
+			<-guard
+		}()
+	}
 
 	failed := 0
 	for _, failure := range failures {
@@ -52,16 +50,12 @@ func runAll(packages []string, script string, maxGoroutines int) int {
 	return failed
 }
 
-// mapParallel applies a function in parallel to each item in a slice.
-func mapParallel[a, b any](maxGoroutines int, items []a, fn func(a) b) []b {
-	result := make([]b, len(items))
-	guard := make(chan struct{}, maxGoroutines)
-	for i, item := range items {
-		guard <- struct{}{} // block if channel is filled
-		go func(i int, item a) {
-			result[i] = fn(item)
-			<-guard
-		}(i, item)
-	}
-	return result
+func printError(f *os.File, pkg string, err error, output string) {
+	fmt.Fprintf(f, "%v\n❌ FAILED: %v\n%v\n%v\n%v\n\n",
+		strings.Repeat("=", 80),
+		pkg,
+		strings.Repeat("-", 80),
+		err,
+		string(output),
+	)
 }