fix: close goroutine pool to prevent goroutine leaks after multiple g…

…enerate calls (#499)

* fix: close goroutine pool to prevent goroutine leaks after multiple generate calls

* test: validate pdf creation

---------

Co-authored-by: Fernando Coelho Saraiva <66834579+Fernando-hub527@users.noreply.github.com>

maroto.go

@@ -3,6 +3,7 @@ package maroto
 import (
 	"errors"
 
+	"github.com/f-amaral/go-async/pool"
 	"github.com/johnfercher/maroto/v2/pkg/consts/generation"
 
 	"github.com/johnfercher/maroto/v2/internal/cache"
@@ -15,8 +16,6 @@ import (
 
 	"github.com/johnfercher/go-tree/node"
 
-	"github.com/f-amaral/go-async/async"
-	"github.com/f-amaral/go-async/pool"
 	"github.com/johnfercher/maroto/v2/pkg/components/col"
 	"github.com/johnfercher/maroto/v2/pkg/components/page"
 	"github.com/johnfercher/maroto/v2/pkg/components/row"
@@ -38,9 +37,6 @@ type Maroto struct {
 	headerHeight  float64
 	footerHeight  float64
 	currentHeight float64
-
-	// Processing
-	pool async.Processor[[]core.Page, []byte]
 }
 
 // GetCurrentConfig is responsible for returning the current settings from the file
@@ -68,12 +64,6 @@ func New(cfgs ...*entity.Config) core.Maroto {
 		config: cfg,
 	}
 
-	if cfg.GenerationMode == generation.Concurrent {
-		p := pool.NewPool[[]core.Page, []byte](cfg.ChunkWorkers, m.processPage,
-			pool.WithSortingOutput[[]core.Page, []byte]())
-		m.pool = p
-	}
-
 	return m
 }
 
@@ -289,6 +279,9 @@ func (m *Maroto) generate() (core.Document, error) {
 }
 
 func (m *Maroto) generateConcurrently() (core.Document, error) {
+	p := pool.NewPool[[]core.Page, []byte](m.config.ChunkWorkers, m.processPage,
+		pool.WithSortingOutput[[]core.Page, []byte]())
+	defer p.Close()
 	chunks := len(m.pages) / m.config.ChunkWorkers
 	if chunks == 0 {
 		chunks = 1
@@ -304,7 +297,7 @@ func (m *Maroto) generateConcurrently() (core.Document, error) {
 		pageGroups = append(pageGroups, m.pages[i:end])
 	}
 
-	processed := m.pool.Process(pageGroups)
+	processed := p.Process(pageGroups)
 	if processed.HasError {
 		return nil, errors.New("an error has occurred while trying to generate PDFs concurrently")
 	}

maroto_test.go

@@ -2,7 +2,9 @@ package maroto_test
 
 import (
 	"fmt"
+	"runtime"
 	"testing"
+	"time"
 
 	"github.com/johnfercher/maroto/v2/pkg/components/code"
 	"github.com/johnfercher/maroto/v2/pkg/components/text"
@@ -369,6 +371,31 @@ func TestMaroto_Generate(t *testing.T) {
 		// Assert
 		test.New(t).Assert(sut.GetStructure()).Equals("maroto_concurrent.json")
 	})
+	t.Run("goroutines do not leak after multiple generate calls on concurrent mode", func(t *testing.T) {
+		// Arrange
+		cfg := config.NewBuilder().
+			WithConcurrentMode(10).
+			Build()
+
+		sut := maroto.New(cfg)
+
+		// Act
+		for i := 0; i < 30; i++ {
+			sut.AddRow(10, col.New(12))
+		}
+		initialGoroutines := runtime.NumGoroutine()
+		_, err1 := sut.Generate()
+		_, err2 := sut.Generate()
+		_, err3 := sut.Generate()
+		time.Sleep(100 * time.Millisecond)
+		finalGoroutines := runtime.NumGoroutine()
+
+		// Assert
+		assert.Nil(t, err1)
+		assert.Nil(t, err2)
+		assert.Nil(t, err3)
+		assert.Equal(t, initialGoroutines, finalGoroutines)
+	})
 	t.Run("page number", func(t *testing.T) {
 		// Arrange
 		cfg := config.NewBuilder().