Remove the WithWorkers option

Situations that concurrent inline parsing is effective are very limited
due to goroutine overheads and a parse context sharing mutex.

README.md

@@ -84,7 +84,7 @@ With options
 
 ```go
 var buf bytes.Buffer
-if err := goldmark.Convert(source, &buf, parser.WithWorkers(16)); err != nil {
+if err := goldmark.Convert(source, &buf, parser.WithContext(ctx)); err != nil {
   panic(err)
 }
 ```
@@ -92,11 +92,6 @@ if err := goldmark.Convert(source, &buf, parser.WithWorkers(16)); err != nil {
 | Functional option | Type | Description |
 | ----------------- | ---- | ----------- |
 | `parser.WithContext` | A parser.Context | Context for the parsing phase. |
-|  parser.WithWorkers | int | Number of goroutines that execute concurrent inline element parsing. |
-
-`parser.WithWorkers` may make performance better a little if markdown text
-is relatively large. Otherwise, `parser.Workers` may cause performance degradation due to
-goroutine overheads.
 
 Custom parser and renderer
 --------------------------
@@ -255,19 +250,15 @@ blackfriday v2 can not simply be compared with other Commonmark compliant librar
 Though goldmark builds clean extensible AST structure and get full compliance with 
 Commonmark, it is resonably fast and less memory consumption.
 
-This benchmark parses a relatively large markdown text. In such text, concurrent parsing
-makes performance better a little.
-
 ```
-goos: windows
+goos: darwin
 goarch: amd64
 pkg: github.com/yuin/goldmark/_benchmark/go
-BenchmarkMarkdown/Blackfriday-v2-4                   200           6199986 ns/op         3320027 B/op      20050 allocs/op
+BenchmarkMarkdown/Blackfriday-v2-12                  337           3407336 ns/op         3261042 B/op      19862 allocs/op
-BenchmarkMarkdown/GoldMark(workers=16)-4             300           5655736 ns/op         2700250 B/op      14494 allocs/op
+BenchmarkMarkdown/GoldMark-12                        302           3947527 ns/op         2574830 B/op      13853 allocs/op
-BenchmarkMarkdown/GoldMark-4                         200           6501805 ns/op         2594488 B/op      13861 allocs/op
+BenchmarkMarkdown/CommonMark-12                      249           4784221 ns/op         2739317 B/op      18824 allocs/op
-BenchmarkMarkdown/CommonMark-4                       200           7803784 ns/op         2752553 B/op      18826 allocs/op
+BenchmarkMarkdown/Lute-12                            285           4178276 ns/op         4639751 B/op      26665 allocs/op
-BenchmarkMarkdown/Lute-4                             200           6920985 ns/op         2984762 B/op      21270 allocs/op
+BenchmarkMarkdown/GoMarkdown-12                        9         114246204 ns/op         2175131 B/op      22172 allocs/op
-BenchmarkMarkdown/GoMarkdown-4                        10         171046030 ns/op         2195980 B/op      22174 allocs/op
 ```
 
 ### against cmark(A CommonMark reference implementation written in c)
@@ -276,15 +267,12 @@ BenchmarkMarkdown/GoMarkdown-4                        10         171046030 ns/op
 ----------- cmark -----------
 file: _data.md
 iteration: 50
-average: 0.0047014618 sec
+average: 0.0037760639 sec
+go run ./goldmark_benchmark.go
 ------- goldmark -------
 file: _data.md
 iteration: 50
-average: 0.0052624750 sec
+average: 0.0040964230 sec
-------- goldmark(workers=16) -------
-file: _data.md
-iteration: 50
-average: 0.0044918780 sec
 ```
 
 As you can see, goldmark performs pretty much equally to the cmark.

_benchmark/cmark/goldmark_benchmark.go

@@ -9,7 +9,6 @@ import (
 	"time"
 
 	"github.com/yuin/goldmark"
-	"github.com/yuin/goldmark/parser"
 	"github.com/yuin/goldmark/renderer/html"
 )
 
@@ -43,18 +42,4 @@ func main() {
 	fmt.Printf("file: %s\n", file)
 	fmt.Printf("iteration: %d\n", n)
 	fmt.Printf("average: %.10f sec\n", float64((int64(sum)/int64(n)))/1000000000.0)
-
-	sum = time.Duration(0)
-	for i := 0; i < n; i++ {
-		start := time.Now()
-		out.Reset()
-		if err := markdown.Convert(source, &out, parser.WithWorkers(16)); err != nil {
-			panic(err)
-		}
-		sum += time.Since(start)
-	}
-	fmt.Printf("------- goldmark(workers=16) -------\n")
-	fmt.Printf("file: %s\n", file)
-	fmt.Printf("iteration: %d\n", n)
-	fmt.Printf("average: %.10f sec\n", float64((int64(sum)/int64(n)))/1000000000.0)
 }

_benchmark/go/benchmark_test.go

@@ -7,26 +7,16 @@ import (
 
 	gomarkdown "github.com/gomarkdown/markdown"
 	"github.com/yuin/goldmark"
-	"github.com/yuin/goldmark/parser"
 	"github.com/yuin/goldmark/renderer/html"
 	"github.com/yuin/goldmark/util"
 	"gitlab.com/golang-commonmark/markdown"
 
-	bf1 "github.com/russross/blackfriday"
 	bf2 "gopkg.in/russross/blackfriday.v2"
 
 	"github.com/b3log/lute"
 )
 
 func BenchmarkMarkdown(b *testing.B) {
-	b.Run("Blackfriday-v1", func(b *testing.B) {
-		r := func(src []byte) ([]byte, error) {
-			out := bf1.MarkdownBasic(src)
-			return out, nil
-		}
-		doBenchmark(b, r)
-	})
-
 	b.Run("Blackfriday-v2", func(b *testing.B) {
 		r := func(src []byte) ([]byte, error) {
 			out := bf2.Run(src)
@@ -35,25 +25,13 @@ func BenchmarkMarkdown(b *testing.B) {
 		doBenchmark(b, r)
 	})
 
-	b.Run("GoldMark(workers=16)", func(b *testing.B) {
-		markdown := goldmark.New(
-			goldmark.WithRendererOptions(html.WithXHTML(), html.WithUnsafe()),
-		)
-		r := func(src []byte) ([]byte, error) {
-			var out bytes.Buffer
-			err := markdown.Convert(src, &out, parser.WithWorkers(16))
-			return out.Bytes(), err
-		}
-		doBenchmark(b, r)
-	})
-
 	b.Run("GoldMark", func(b *testing.B) {
 		markdown := goldmark.New(
 			goldmark.WithRendererOptions(html.WithXHTML(), html.WithUnsafe()),
 		)
 		r := func(src []byte) ([]byte, error) {
 			var out bytes.Buffer
-			err := markdown.Convert(src, &out, parser.WithWorkers(0))
+			err := markdown.Convert(src, &out)
 			return out.Bytes(), err
 		}
 		doBenchmark(b, r)
@@ -70,12 +48,15 @@ func BenchmarkMarkdown(b *testing.B) {
 	})
 
 	b.Run("Lute", func(b *testing.B) {
-		luteEngine := lute.New(
+		luteEngine := lute.New()
-			lute.GFM(false),
+		luteEngine.SetGFMAutoLink(false)
-			lute.CodeSyntaxHighlight(false),
+		luteEngine.SetGFMStrikethrough(false)
-			lute.SoftBreak2HardBreak(false),
+		luteEngine.SetGFMTable(false)
-			lute.AutoSpace(false),
+		luteEngine.SetGFMTaskListItem(false)
-			lute.FixTermTypo(false))
+		luteEngine.SetCodeSyntaxHighlight(false)
+		luteEngine.SetSoftBreak2HardBreak(false)
+		luteEngine.SetAutoSpace(false)
+		luteEngine.SetFixTermTypo(false)
 		r := func(src []byte) ([]byte, error) {
 			out, err := luteEngine.MarkdownStr("Benchmark", util.BytesToReadOnlyString(src))
 			return util.StringToReadOnlyBytes(out), err

extension/footnote.go

@@ -140,7 +140,7 @@ func (s *footnoteParser) Parse(parent gast.Node, block text.Reader, pc parser.Co
 	block.Advance(closes + 1)
 
 	var list *ast.FootnoteList
-	if tlist := pc.Root().Get(footnoteListKey); tlist != nil {
+	if tlist := pc.Get(footnoteListKey); tlist != nil {
 		list = tlist.(*ast.FootnoteList)
 	}
 	if list == nil {

parser/link.go

@@ -169,7 +169,7 @@ func (s *linkParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.N
 		block.SetPosition(l, pos)
 		ssegment := text.NewSegment(last.Segment.Stop, segment.Start)
 		maybeReference := block.Value(ssegment)
-		ref, ok := pc.Root().Reference(util.ToLinkReference(maybeReference))
+		ref, ok := pc.Reference(util.ToLinkReference(maybeReference))
 		if !ok {
 			ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
 			return nil
@@ -243,7 +243,7 @@ func (s *linkParser) parseReferenceLink(parent ast.Node, last *linkLabelState, b
 		maybeReference = block.Value(ssegment)
 	}
 
-	ref, ok := pc.Root().Reference(util.ToLinkReference(maybeReference))
+	ref, ok := pc.Reference(util.ToLinkReference(maybeReference))
 	if !ok {
 		return nil, true
 	}

parser/parser.go

@@ -196,9 +196,6 @@ type Context interface {
 
 	// LastOpenedBlock returns a last node that is currently in parsing.
 	LastOpenedBlock() Block
-
-	// Root returns a context shared accross goroutines.
-	Root() Context
 }
 
 type parseContext struct {
@@ -210,7 +207,6 @@ type parseContext struct {
 	delimiters    *Delimiter
 	lastDelimiter *Delimiter
 	openedBlocks  []Block
-	root          Context
 }
 
 // NewContext returns a new Context.
@@ -224,7 +220,6 @@ func NewContext() Context {
 		delimiters:    nil,
 		lastDelimiter: nil,
 		openedBlocks:  []Block{},
-		root:          nil,
 	}
 }
 
@@ -361,140 +356,6 @@ func (p *parseContext) LastOpenedBlock() Block {
 	return Block{}
 }
 
-func (p *parseContext) Root() Context {
-	if p.root == nil {
-		return p
-	}
-	return p.root
-}
-
-type concurrentParseContext struct {
-	delegate Context
-	m        sync.RWMutex
-	root     Context
-}
-
-func NewConcurrentContext(delegate Context) Context {
-	return &concurrentParseContext{
-		delegate: delegate,
-		root:     nil,
-	}
-}
-
-func (p *concurrentParseContext) Get(key ContextKey) interface{} {
-	p.m.RLock()
-	defer p.m.RUnlock()
-	ret := p.delegate.Get(key)
-	return ret
-}
-
-func (p *concurrentParseContext) Set(key ContextKey, value interface{}) {
-	p.m.Lock()
-	defer p.m.Unlock()
-	p.delegate.Set(key, value)
-}
-
-func (p *concurrentParseContext) IDs() IDs {
-	return p.delegate.IDs()
-}
-
-func (p *concurrentParseContext) BlockOffset() int {
-	return p.delegate.BlockOffset()
-}
-
-func (p *concurrentParseContext) SetBlockOffset(v int) {
-	p.m.Lock()
-	defer p.m.Unlock()
-	p.delegate.SetBlockOffset(v)
-}
-
-func (p *concurrentParseContext) BlockIndent() int {
-	return p.delegate.BlockIndent()
-}
-
-func (p *concurrentParseContext) SetBlockIndent(v int) {
-	p.m.Lock()
-	defer p.m.Unlock()
-	p.delegate.SetBlockIndent(v)
-}
-
-func (p *concurrentParseContext) LastDelimiter() *Delimiter {
-	return p.delegate.LastDelimiter()
-}
-
-func (p *concurrentParseContext) FirstDelimiter() *Delimiter {
-	return p.delegate.FirstDelimiter()
-}
-
-func (p *concurrentParseContext) PushDelimiter(d *Delimiter) {
-	p.m.Lock()
-	defer p.m.Unlock()
-	p.delegate.PushDelimiter(d)
-}
-
-func (p *concurrentParseContext) RemoveDelimiter(d *Delimiter) {
-	p.m.Lock()
-	defer p.m.Unlock()
-	p.delegate.RemoveDelimiter(d)
-}
-
-func (p *concurrentParseContext) ClearDelimiters(bottom ast.Node) {
-	p.m.Lock()
-	defer p.m.Unlock()
-	p.delegate.ClearDelimiters(bottom)
-}
-
-func (p *concurrentParseContext) AddReference(ref Reference) {
-	p.m.Lock()
-	defer p.m.Unlock()
-	p.delegate.AddReference(ref)
-}
-
-func (p *concurrentParseContext) Reference(label string) (Reference, bool) {
-	p.m.RLock()
-	defer p.m.RUnlock()
-	v, ok := p.delegate.Reference(label)
-	return v, ok
-}
-
-func (p *concurrentParseContext) References() []Reference {
-	p.m.RLock()
-	defer p.m.RUnlock()
-	ret := p.delegate.References()
-	return ret
-}
-
-func (p *concurrentParseContext) String() string {
-	p.m.RLock()
-	defer p.m.RUnlock()
-	ret := p.delegate.String()
-	return ret
-}
-
-func (p *concurrentParseContext) OpenedBlocks() []Block {
-	return p.delegate.OpenedBlocks()
-}
-
-func (p *concurrentParseContext) SetOpenedBlocks(v []Block) {
-	p.m.Lock()
-	defer p.m.Unlock()
-	p.delegate.SetOpenedBlocks(v)
-}
-
-func (p *concurrentParseContext) LastOpenedBlock() Block {
-	p.m.RLock()
-	defer p.m.RUnlock()
-	ret := p.delegate.LastOpenedBlock()
-	return ret
-}
-
-func (p *concurrentParseContext) Root() Context {
-	if p.root == nil {
-		return p
-	}
-	return p.root
-}
-
 // State represents parser's state.
 // State is designed to use as a bit flag.
 type State int
@@ -906,7 +767,6 @@ func (p *parser) addASTTransformer(v util.PrioritizedValue, options map[OptionNa
 // A ParseConfig struct is a data structure that holds configuration of the Parser.Parse.
 type ParseConfig struct {
 	Context Context
-	Workers int
 }
 
 // A ParseOption is a functional option type for the Parser.Parse.
@@ -920,15 +780,6 @@ func WithContext(context Context) ParseOption {
 	}
 }
 
-// WithWorkers is a functional option that allow you to set
-// number of inline parsing workers(goroutines).
-// If num is 0, inline parsing will never be multithreaded.
-func WithWorkers(num int) ParseOption {
-	return func(c *ParseConfig) {
-		c.Workers = num
-	}
-}
-
 func (p *parser) Parse(reader text.Reader, opts ...ParseOption) ast.Node {
 	p.initSync.Do(func() {
 		p.config.BlockParsers.Sort()
@@ -966,45 +817,10 @@ func (p *parser) Parse(reader text.Reader, opts ...ParseOption) ast.Node {
 	root := ast.NewDocument()
 	p.parseBlocks(root, reader, pc)
 
-	if c.Workers < 2 {
 	blockReader := text.NewBlockReader(reader.Source(), nil)
 	p.walkBlock(root, func(node ast.Node) {
 		p.parseBlock(blockReader, node, pc)
 	})
-	} else {
-		nodes := make([]ast.Node, 0, 100)
-		p.walkBlock(root, func(node ast.Node) {
-			nodes = append(nodes, node)
-		})
-		max := (len(nodes) / c.Workers) - 1
-		if max < 0 {
-			blockReader := text.NewBlockReader(reader.Source(), nil)
-			p.walkBlock(root, func(node ast.Node) {
-				p.parseBlock(blockReader, node, pc)
-			})
-		} else {
-			rootContext := NewConcurrentContext(pc)
-			var wg sync.WaitGroup
-			for i := 0; i <= max; i++ {
-				from := i * c.Workers
-				to := from + c.Workers
-				if i == max {
-					to = len(nodes)
-				}
-				wg.Add(1)
-				go func(wg *sync.WaitGroup) {
-					blockReader := text.NewBlockReader(reader.Source(), nil)
-					pc := NewContext()
-					pc.(*parseContext).root = rootContext
-					for _, n := range nodes[from:to] {
-						p.parseBlock(blockReader, n, pc)
-					}
-					wg.Done()
-				}(&wg)
-			}
-			wg.Wait()
-		}
-	}
 	for _, at := range p.astTransformers {
 		at.Transform(root, reader, pc)
 	}

testutil/testutil.go

@@ -10,7 +10,6 @@ import (
 	"strings"
 
 	"github.com/yuin/goldmark"
-	"github.com/yuin/goldmark/parser"
 	"github.com/yuin/goldmark/util"
 )
 
@@ -131,7 +130,7 @@ Actual
 		}
 	}()
 
-	if err := m.Convert([]byte(testCase.Markdown), &out, parser.WithWorkers(16)); err != nil {
+	if err := m.Convert([]byte(testCase.Markdown), &out); err != nil {
 		panic(err)
 	}
 	ok = bytes.Equal(bytes.TrimSpace(out.Bytes()), bytes.TrimSpace([]byte(testCase.Expected)))