race condition pointers example solutions added in a file. Benchmark …

…tests added to compare solutions. Test running guide added to Readme file.

102-concurrency/goroutines/race-condition-pointers-fix/README.md

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+## How to run Benchmark
+
+* Run this command for Atomic Example.
+
+`$go test -benchmem -run=^$ -bench ^BenchmarkAtomic$`
+
+* Run this command for Mutex Lock Example.
+
+`$go test -benchmem -run=^$ -bench ^BenchmarkMutexLock$`
+
+### Example Results
+
+* **Atomic**
+  * goos: darwin
+  * goarch: amd64
+  * pkg: raceConditionPointersFix
+  * cpu: Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz
+  * BenchmarkAtomic-4 --- 4977807 --- 236.2 ns/op --- 24 B/op --- 1 allocs/op
+  * PASS
+  * ok raceConditionPointersFix 1.895s
+
+
+* **Mutex Lock**
+  * goos: darwin
+  * goarch: amd64
+  * pkg: raceConditionPointersFix
+  * cpu: Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz
+  * BenchmarkMutexLock-4 --- 4626063 --- 260.3 ns/op --- 33 B/op          1 allocs/op
+  * PASS
+  * ok raceConditionPointersFix 1.592s
+

102-concurrency/goroutines/race-condition-pointers-fix/go.mod

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+module raceConditionPointersFix
+
+go 1.17

102-concurrency/goroutines/race-condition-pointers-fix/race-condition-pointers-fix.go

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+package raceConditionPointersFix
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+)
+
+type RaceTest struct {
+	Val int32
+}
+
+func main() {
+	raceTest := &RaceTest{}
+
+	wg := &sync.WaitGroup{}
+	wg.Add(10000)
+
+	// mtx := &sync.Mutex{} // This line for mutex lock method
+
+	for i:=0; i<10000; i++ {
+		go incrementWithAtomic(raceTest, wg)
+		// go incrementWithLock(raceTest, wg, mtx) // This line for mutex lock method
+	}
+
+	wg.Wait()
+
+	fmt.Println(raceTest)
+}
+
+func incrementWithAtomic(rt *RaceTest, wg *sync.WaitGroup) {
+	atomic.AddInt32(&rt.Val, 1)
+	wg.Done()
+}
+
+func incrementWithLock(rt *RaceTest, wg *sync.WaitGroup, mtx *sync.Mutex) {
+	mtx.Lock()
+	rt.Val += 1
+	mtx.Unlock()
+	wg.Done()
+}

102-concurrency/goroutines/race-condition-pointers-fix/race-condition-pointers-fix_test.go

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+package raceConditionPointersFix
+
+import (
+	"sync"
+	"testing"
+)
+
+// go test -benchmem -run=^$ -bench ^BenchmarkAtomic$
+func BenchmarkAtomic(b *testing.B) {
+	raceTest := &RaceTest{}
+	wg := &sync.WaitGroup{}
+	wg.Add(b.N)
+
+	for i := 0; i < b.N; i++ {
+		go incrementWithAtomic(raceTest, wg)
+	}
+
+	wg.Wait()
+}
+
+// go test -benchmem -run=^$ -bench ^BenchmarkMutexLock$
+func BenchmarkMutexLock(b *testing.B) {
+	raceTest := &RaceTest{}
+
+	wg := &sync.WaitGroup{}
+	wg.Add(b.N)
+
+	mtx := &sync.Mutex{}
+
+	for i := 0; i < b.N; i++ {
+		go incrementWithLock(raceTest, wg, mtx)
+	}
+
+	wg.Wait()
+}