fix incorrect synchronization and add race unit test

worker/agent.go

@@ -111,7 +111,7 @@ func (a *agent) work() {
 }
 
 func (a *agent) disconnect_error(err error) {
-	a.Unlock()
+	a.Lock()
 	defer a.Unlock()
 
 	if a.conn != nil {

worker/worker_racy_test.go

@@ -0,0 +1,59 @@
+package worker
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+)
+
+func TestWorkerRace(t *testing.T) {
+	// from example worker
+	// An example of worker
+	w := New(Unlimited)
+	defer w.Close()
+	// Add a gearman job server
+	if err := w.AddServer(Network, "127.0.0.1:4730"); err != nil {
+		t.Fatal(err)
+	}
+	// A function for handling jobs
+	foobar := func(job Job) ([]byte, error) {
+		// Do nothing here
+		return nil, nil
+	}
+	// Add the function to worker
+	if err := w.AddFunc("foobar", foobar, 0); err != nil {
+		fmt.Println(err)
+		return
+	}
+	var wg sync.WaitGroup
+	// A custome handler, for handling other results, eg. ECHO, dtError.
+	w.JobHandler = func(job Job) error {
+		if job.Err() == nil {
+			fmt.Println(string(job.Data()))
+		} else {
+			fmt.Println(job.Err())
+		}
+		wg.Done()
+		return nil
+	}
+	// An error handler for handling worker's internal errors.
+	w.ErrorHandler = func(e error) {
+		fmt.Println(e)
+		// Ignore the error or shutdown the worker
+	}
+	// Tell Gearman job server: I'm ready!
+	if err := w.Ready(); err != nil {
+		fmt.Println(err)
+		return
+	}
+	// Running main loop
+	go w.Work()
+	wg.Add(1)
+	// calling Echo
+	w.Echo([]byte("Hello"))
+	// Waiting results
+	wg.Wait()
+
+	// tear down
+	w.Close()
+}