Merge pull request #560 from devlights/add-slice-not-threadsafe-example

Author: devlights

examples/singleapp/slice_is_not_threadsafe/Taskfile.yml

@@ -0,0 +1,27 @@
+version: '3'
+
+tasks:
+  fmt:
+    cmds:
+      - go fmt ./...
+  vet:
+    cmds:
+      - go vet ./...
+  run:
+    cmds:
+      - cmd: for i in {1..10} ; do go run race/main.go; done
+        silent: true
+  run-notrace:
+    cmds:
+      - cmd: for i in {1..10} ; do go run notrace/main.go; done
+        silent: true
+  run-notrace2:
+    cmds:
+      - cmd: for i in {1..10} ; do go run notrace2/main.go; done
+        silent: true
+  run-with-raceoption:
+    cmds:
+      - cmd: go run -race race/main.go
+        ignore_error: true
+      - go run -race notrace/main.go
+      - go run -race notrace2/main.go

examples/singleapp/slice_is_not_threadsafe/notrace/main.go

@@ -0,0 +1,69 @@
+// スライス操作 (スライスヘッダの書き換え）はスレッドセーフでは無いというのを示すサンプルです。
+// 本サンプルはデータ競合が発生しません。
+//
+// REFERENCES:
+//   - https://stackoverflow.com/questions/44152988/append-not-thread-safe
+//   - https://stackoverflow.com/questions/49879322/can-i-concurrently-write-different-slice-elements
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strconv"
+	"sync"
+)
+
+type data struct {
+	value string
+}
+
+func (me data) String() string {
+	return me.value
+}
+
+func main() {
+	var (
+		verbose = flag.Bool("verbose", false, "verbose output")
+	)
+	flag.Parse()
+
+	var (
+		mu  = sync.Mutex{}
+		src = make([]data, 100)
+		dst = make([]data, 0)
+	)
+
+	for i := 0; i < len(src); i++ {
+		src[i].value = strconv.Itoa(i)
+	}
+
+	wg := sync.WaitGroup{}
+	for _, v := range src {
+		wg.Add(1)
+		go func(v data) {
+			defer wg.Done()
+
+			var tmp data
+			tmp.value = v.value
+
+			mu.Lock()
+			dst = append(dst, tmp)
+			mu.Unlock()
+		}(v)
+	}
+
+	wg.Wait()
+
+	fmt.Printf("src-len=%d\tdst-len=%d\n", len(src), len(dst))
+
+	if *verbose {
+		fmt.Println("=========== SRC ===========")
+		for _, v := range src {
+			fmt.Println(v)
+		}
+		fmt.Println("=========== DST ===========")
+		for _, v := range dst {
+			fmt.Println(v)
+		}
+	}
+}

examples/singleapp/slice_is_not_threadsafe/notrace2/main.go

@@ -0,0 +1,66 @@
+// スライス操作 (スライスヘッダの書き換え）はスレッドセーフでは無いというのを示すサンプルです。
+// 本サンプルはデータ競合が発生しません。
+//
+// REFERENCES:
+//   - https://stackoverflow.com/questions/44152988/append-not-thread-safe
+//   - https://stackoverflow.com/questions/49879322/can-i-concurrently-write-different-slice-elements
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strconv"
+	"sync"
+)
+
+type data struct {
+	value string
+}
+
+func (me data) String() string {
+	return me.value
+}
+
+func main() {
+	var (
+		verbose = flag.Bool("verbose", false, "verbose output")
+	)
+	flag.Parse()
+
+	var (
+		src = make([]data, 100)
+		dst = make([]data, len(src))
+	)
+
+	for i := 0; i < len(src); i++ {
+		src[i].value = strconv.Itoa(i)
+	}
+
+	wg := sync.WaitGroup{}
+	for i, v := range src {
+		wg.Add(1)
+		go func(i int, v data) {
+			defer wg.Done()
+
+			var tmp data
+			tmp.value = v.value
+
+			dst[i] = tmp
+		}(i, v)
+	}
+
+	wg.Wait()
+
+	fmt.Printf("src-len=%d\tdst-len=%d\n", len(src), len(dst))
+
+	if *verbose {
+		fmt.Println("=========== SRC ===========")
+		for _, v := range src {
+			fmt.Println(v)
+		}
+		fmt.Println("=========== DST ===========")
+		for _, v := range dst {
+			fmt.Println(v)
+		}
+	}
+}

examples/singleapp/slice_is_not_threadsafe/race/main.go

@@ -0,0 +1,66 @@
+// スライス操作 (スライスヘッダの書き換え）はスレッドセーフでは無いというのを示すサンプルです。
+// 本サンプルはデータ競合が発生しています。
+//
+// REFERENCES:
+//   - https://stackoverflow.com/questions/44152988/append-not-thread-safe
+//   - https://stackoverflow.com/questions/49879322/can-i-concurrently-write-different-slice-elements
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strconv"
+	"sync"
+)
+
+type data struct {
+	value string
+}
+
+func (me data) String() string {
+	return me.value
+}
+
+func main() {
+	var (
+		verbose = flag.Bool("verbose", false, "verbose output")
+	)
+	flag.Parse()
+
+	var (
+		src = make([]data, 100)
+		dst = make([]data, 0)
+	)
+
+	for i := 0; i < len(src); i++ {
+		src[i].value = strconv.Itoa(i)
+	}
+
+	wg := sync.WaitGroup{}
+	for _, v := range src {
+		wg.Add(1)
+		go func(v data) {
+			defer wg.Done()
+
+			var tmp data
+			tmp.value = v.value
+
+			dst = append(dst, tmp)
+		}(v)
+	}
+
+	wg.Wait()
+
+	fmt.Printf("src-len=%d\tdst-len=%d\n", len(src), len(dst))
+
+	if *verbose {
+		fmt.Println("=========== SRC ===========")
+		for _, v := range src {
+			fmt.Println(v)
+		}
+		fmt.Println("=========== DST ===========")
+		for _, v := range dst {
+			fmt.Println(v)
+		}
+	}
+}