diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index 904204a..64f7ce8 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -29,6 +29,9 @@ jobs:
     - name: Test
       run: go test -v ./...
 
+    - name: Run coverage
+      run: go test -race -coverprofile=coverage.txt -covermode=atomic ./...
+
     - 
       name: Upload coverage reports to Codecov
       uses: codecov/codecov-action@v4.0.1
diff --git a/status.go b/status.go
index 05d2e4e..3de5b68 100644
--- a/status.go
+++ b/status.go
@@ -5,6 +5,7 @@ import (
 	"time"
 )
 
+// Status represents the status of the job.
 type Status struct {
 	Timestamp   string `json:"timestamp"`
 	NumFailed   int64  `json:"num_failed"`
@@ -31,12 +32,22 @@ func newStatusManager() *statusManager {
 	}
 }
 
+func (sm *statusManager) notify() {
+	status := sm.Snapshot()
+	for _, ch := range sm.statusChans {
+		ch <- status
+	}
+}
+
+// Start starts the status manager.
+// It will notify all the status channels every second.
 func (sm *statusManager) Start() {
 	for range sm.ticker.C {
 		sm.notify()
 	}
 }
 
+// Stop stops the status manager.
 func (sm *statusManager) Stop() {
 	sm.notify()
 	sm.ticker.Stop()
@@ -45,32 +56,43 @@ func (sm *statusManager) Stop() {
 	}
 }
 
+// IncFailed increments the number of failed jobs.
 func (sm *statusManager) IncFailed() {
 	sm.mutex.Lock()
 	sm.numFailed++
 	sm.mutex.Unlock()
 }
 
+// IncSucceed increments the number of succeed jobs.
 func (sm *statusManager) IncSucceed() {
 	sm.mutex.Lock()
 	sm.numSucceed++
 	sm.mutex.Unlock()
 }
 
+// SetTotal sets the total number of jobs.
+// It should be called before the job starts.
 func (sm *statusManager) SetTotal(total int64) {
 	sm.mutex.Lock()
 	sm.numTotal = total
 	sm.mutex.Unlock()
 }
 
+// StatusChan returns a channel that will receive the status of the job.
+// The status will be sent every second. It should be called before the job starts.
+// You can call it multiple times to get multiple channels.
 func (sm *statusManager) StatusChan() <-chan Status {
 	ch := make(chan Status)
 	sm.statusChans = append(sm.statusChans, ch)
 	return ch
 }
 
+// Snapshot returns the current status of the job.
 func (sm *statusManager) Snapshot() Status {
-	sm.mutex.Lock()
+	defer func() func() {
+		sm.mutex.Lock()
+		return func() { sm.mutex.Unlock() }
+	}()()
 	status := Status{
 		Timestamp:   time.Now().Format(time.RFC3339),
 		NumFailed:   sm.numFailed,
@@ -78,13 +100,5 @@ func (sm *statusManager) Snapshot() Status {
 		NumFinished: sm.numFailed + sm.numSucceed,
 		NumTotal:    sm.numTotal,
 	}
-	sm.mutex.Unlock()
 	return status
 }
-
-func (sm *statusManager) notify() {
-	status := sm.Snapshot()
-	for _, ch := range sm.statusChans {
-		ch <- status
-	}
-}