英文:
Using a Goroutine actually takes longer to execute
问题
我确定我做错了什么，我有一个Go程序，它解析OBJ格式的3D模型并输出一个json对象。当我在不添加goroutines的情况下运行它时，我得到以下输出：
$ go run objParser.go ak47.obj extincteur_obj.obj
--从ak47.obj创建ak47.json3d
--导出了85772个面和89088个顶点
--从extincteur_obj.obj创建extincteur_obj.json3d
--导出了150316个面和151425个顶点
在8.4963秒内解析了2个文件
然后我添加了goroutines，我得到了这个输出：
$ go run objParser.go ak47.obj extincteur_obj.obj
--从ak47.obj创建ak47.json3d
--从extincteur_obj.obj创建extincteur_obj.json3d
--导出了85772个面和89088个顶点
--导出了150316个面和151425个顶点
在10.23137秒内解析了2个文件
打印的顺序是我预期的，因为解析是交错进行的，但我不知道为什么实际上需要更长的时间！代码非常长，我剪掉了一些，但仍然很长，对此很抱歉！
package main
func parseFile(name string, finished chan int) {
var Verts []*Vertex
var Texs []*TexCoord
var Faces []*Face
var objFile, mtlFile, jsonFile *os.File
var parseMaterial bool
// Set up files and i/o
inName := name
outName := strings.Replace(inName, ".obj", ".json3d", -1)
parseMaterial = false
fmt.Printf("--"+FgGreen+"Creating"+Reset+" %s from %s\n", outName, inName)
var err error
var part []byte
var prefix bool
if objFile, err = os.Open(inName); err != nil {
fmt.Println(FgRed+"!!Failed to open input file!!"+Reset)
return
}
if jsonFile, err = os.Create(outName); err != nil {
fmt.Println(FgRed+"!!Failed to create output file!!"+Reset)
return
}
reader := bufio.NewReader(objFile)
writer := bufio.NewWriter(jsonFile)
buffer := bytes.NewBuffer(make([]byte, 1024))
// Read the file in and parse out what we need
for {
if part, prefix, err = reader.ReadLine(); err != nil {
break
}
buffer.Write(part)
if !prefix {
line := buffer.String()
if(strings.Contains(line, "v ")) {
Verts = append(Verts, parseVertex(line))
} else if(strings.Contains(line, "vt ")) {
Texs = append(Texs, parseTexCoord(line))
} else if(strings.Contains(line, "f ")) {
Faces = append(Faces, parseFace(line, Verts, Texs))
} else if(strings.Contains(line, "mtllib ")) {
mtlName := strings.Split(line, " ")[1]
if mtlFile, err = os.Open(mtlName); err != nil {
fmt.Printf("--"+FgRed+"Failed to find material file: %s\n"+Reset, mtlName)
parseMaterial = false
} else {
parseMaterial = true
}
}
buffer.Reset()
}
}
if err == io.EOF {
err = nil
}
objFile.Close()
// Write out the data
writer.WriteString("{\"obj\":[\n");
// Write out the verts
writer.WriteString("{\"vrt\":[\n");
for i, vert := range Verts {
writer.WriteString(vert.String())
if i < len(Verts) - 1 { writer.WriteString(",") }
writer.WriteString("\n")
}
// Write out the faces
writer.WriteString("],\"fac\":[\n")
for i, face := range Faces {
writer.WriteString(face.String(true))
if i < len(Faces) - 1 { writer.WriteString(",") }
writer.WriteString("\n")
}
// Write out the normals
writer.WriteString("],\"nrm\":[")
for i, face := range Faces {
writer.WriteString("[")
for j, vert := range face.verts {
length := math.Sqrt((vert.X * vert.X) + (vert.Y * vert.Y) + (vert.Z * vert.Z))
x := vert.X / length
y := vert.Y / length
z := vert.Z / length
normal := fmt.Sprintf("[%f,%f,%f]", x, y, z)
writer.WriteString(normal)
if(j < len(face.verts)-1) { writer.WriteString(",") }
}
writer.WriteString("]")
//writer.WriteString("[0, 1, 0]")
if i < len(Faces) - 1 { writer.WriteString(",") }
writer.WriteString("\n")
}
// Write out the tex coords
writer.WriteString("],\"tex\":[")
for i, face := range Faces {
writer.WriteString("[")
writer.WriteString(face.tex[0].String())
writer.WriteString(",")
writer.WriteString(face.tex[1].String())
writer.WriteString(",")
writer.WriteString(face.tex[2].String())
writer.WriteString("]")
if i < len(Faces) - 1 { writer.WriteString(",") }
writer.WriteString("\n")
}
// Close obj block
writer.WriteString("]}]");
if parseMaterial {
writer.WriteString(",mat:[{");
reader := bufio.NewReader(mtlFile)
// Read the file in and parse out what we need
for {
if part, prefix, err = reader.ReadLine(); err != nil {
break
}
buffer.Write(part)
if !prefix {
line := buffer.String()
if(strings.Contains(line, "map_Kd ")) {
parts := strings.Split(line, " ")
entry := fmt.Sprintf("\"t\":\"%s\",", parts[1])
writer.WriteString(entry)
width, height := 256, 256
var imageFile *os.File
if imageFile, err = os.Open(parts[1]); err != nil {
fmt.Printf("--"+FgRed+"Failed to find %s, defaulting to 256x256"+Reset+"\n", parts[1])
return
} else {
var config image.Config
imageReader := bufio.NewReader(imageFile)
config, err = jpeg.DecodeConfig(imageReader)
width, height = config.Width, config.Height
fmt.Printf("--"+FgGreen+"Verifing"+Reset+" that %s is %dpx x %dpx\n", parts[1], width, height)
}
size := fmt.Sprintf("\"w\":%d,\"h\":%d,", width, height)
writer.WriteString(size)
} else if(strings.Contains(line, "Kd ")) {
parts := strings.Split(line, " ")
entry := fmt.Sprintf("\"r\":%s, \"g\":%s, \"b\":%s,", parts[1], parts[2], parts[3])
writer.WriteString(entry)
}
buffer.Reset()
}
}
if err == io.EOF {
err = nil
}
writer.WriteString("\"res\":100,\"uv\":true}]");
}
// Close json
writer.WriteString("}");
writer.Flush()
jsonFile.Close()
fmt.Printf("--"+FgGreen+"Exported"+Reset+" %d faces with %d verticies\n", len(Faces), len(Verts))
finished <- -1
}
func main(){
// Verify we were called correctly
if len(os.Args) < 2 {
fmt.Println("Usage: go run objParser.go <OBJ File>");
return
}
files := len(os.Args)
finished := make(chan int)
now := time.Now()
for i := 1; i < files; i++ {
go parseFile(os.Args[i], finished)
}
for i := 1; i < files; i++ {
<- finished
}
fmt.Printf("Parsed %d files in %s\n", files-1, time.Since(now))
}
英文:
I'm sure that I'm doing something wrong, I have a Go program that parses in 3D models in OBJ format and outputs a json object. When I run it without adding in goroutines I get the following output:
$ go run objParser.go ak47.obj extincteur_obj.obj
--Creating ak47.json3d from ak47.obj
--Exported 85772 faces with 89088 verticies
--Creating extincteur_obj.json3d from extincteur_obj.obj
--Exported 150316 faces with 151425 verticies
Parsed 2 files in 8.4963s
Then I added in the goroutines and I get this output:
$ go run objParser.go ak47.obj extincteur_obj.obj
--Creating ak47.json3d from ak47.obj
--Creating extincteur_obj.json3d from extincteur_obj.obj
--Exported 85772 faces with 89088 verticies
--Exported 150316 faces with 151425 verticies
Parsed 2 files in 10.23137s
The order of how it's printed is what I expected given the interlacing of the parsing but I have no idea why it actually takes longer! The code is pretty long, I snipped what I could but it's still pretty long, sorry about that!
package main
func parseFile(name string, finished chan int) {
var Verts []*Vertex
var Texs []*TexCoord
var Faces []*Face
var objFile, mtlFile, jsonFile *os.File
var parseMaterial bool
// Set up files and i/o
inName := name
outName := strings.Replace(inName, ".obj", ".json3d", -1)
parseMaterial = false
fmt.Printf("--"+FgGreen+"Creating"+Reset+" %s from %s\n", outName, inName)
var err error
var part []byte
var prefix bool
if objFile, err = os.Open(inName); err != nil {
fmt.Println(FgRed+"!!Failed to open input file!!"+Reset)
return
}
if jsonFile, err = os.Create(outName); err != nil {
fmt.Println(FgRed+"!!Failed to create output file!!"+Reset)
return
}
reader := bufio.NewReader(objFile)
writer := bufio.NewWriter(jsonFile)
buffer := bytes.NewBuffer(make([]byte, 1024))
// Read the file in and parse out what we need
for {
if part, prefix, err = reader.ReadLine(); err != nil {
break
}
buffer.Write(part)
if !prefix {
line := buffer.String()
if(strings.Contains(line, "v ")) {
Verts = append(Verts, parseVertex(line))
} else if(strings.Contains(line, "vt ")) {
Texs = append(Texs, parseTexCoord(line))
} else if(strings.Contains(line, "f ")) {
Faces = append(Faces, parseFace(line, Verts, Texs))
} else if(strings.Contains(line, "mtllib ")) {
mtlName := strings.Split(line, " ")[1]
if mtlFile, err = os.Open(mtlName); err != nil {
fmt.Printf("--"+FgRed+"Failed to find material file: %s\n"+Reset, mtlName)
parseMaterial = false
} else {
parseMaterial = true
}
}
buffer.Reset()
}
}
if err == io.EOF {
err = nil
}
objFile.Close()
// Write out the data
writer.WriteString("{\"obj\":[\n");
// Write out the verts
writer.WriteString("{\"vrt\":[\n");
for i, vert := range Verts {
writer.WriteString(vert.String())
if i < len(Verts) - 1 { writer.WriteString(",") }
writer.WriteString("\n")
}
// Write out the faces
writer.WriteString("],\"fac\":[\n")
for i, face := range Faces {
writer.WriteString(face.String(true))
if i < len(Faces) - 1 { writer.WriteString(",") }
writer.WriteString("\n")
}
// Write out the normals
writer.WriteString("],\"nrm\":[")
for i, face := range Faces {
writer.WriteString("[")
for j, vert := range face.verts {
length := math.Sqrt((vert.X * vert.X) + (vert.Y * vert.Y) + (vert.Z * vert.Z))
x := vert.X / length
y := vert.Y / length
z := vert.Z / length
normal := fmt.Sprintf("[%f,%f,%f]", x, y, z)
writer.WriteString(normal)
if(j < len(face.verts)-1) { writer.WriteString(",") }
}
writer.WriteString("]")
//writer.WriteString("[0, 1, 0]")
if i < len(Faces) - 1 { writer.WriteString(",") }
writer.WriteString("\n")
}
// Write out the tex coords
writer.WriteString("],\"tex\":[")
for i, face := range Faces {
writer.WriteString("[")
writer.WriteString(face.tex[0].String())
writer.WriteString(",")
writer.WriteString(face.tex[1].String())
writer.WriteString(",")
writer.WriteString(face.tex[2].String())
writer.WriteString("]")
if i < len(Faces) - 1 { writer.WriteString(",") }
writer.WriteString("\n")
}
// Close obj block
writer.WriteString("]}]");
if parseMaterial {
writer.WriteString(",mat:[{");
reader := bufio.NewReader(mtlFile)
// Read the file in and parse out what we need
for {
if part, prefix, err = reader.ReadLine(); err != nil {
break
}
buffer.Write(part)
if !prefix {
line := buffer.String()
if(strings.Contains(line, "map_Kd ")) {
parts := strings.Split(line, " ")
entry := fmt.Sprintf("\"t\":\"%s\",", parts[1])
writer.WriteString(entry)
width, height := 256, 256
var imageFile *os.File
if imageFile, err = os.Open(parts[1]); err != nil {
fmt.Printf("--"+FgRed+"Failed to find %s, defaulting to 256x256"+Reset+"\n", parts[1])
return
} else {
var config image.Config
imageReader := bufio.NewReader(imageFile)
config, err = jpeg.DecodeConfig(imageReader)
width, height = config.Width, config.Height
fmt.Printf("--"+FgGreen+"Verifing"+Reset+" that %s is %dpx x %dpx\n", parts[1], width, height)
}
size := fmt.Sprintf("\"w\":%d,\"h\":%d,", width, height)
writer.WriteString(size)
} else if(strings.Contains(line, "Kd ")) {
parts := strings.Split(line, " ")
entry := fmt.Sprintf("\"r\":%s, \"g\":%s, \"b\":%s,", parts[1], parts[2], parts[3])
writer.WriteString(entry)
}
buffer.Reset()
}
}
if err == io.EOF {
err = nil
}
writer.WriteString("\"res\":100,\"uv\":true}]");
}
// Close json
writer.WriteString("}");
writer.Flush()
jsonFile.Close()
fmt.Printf("--"+FgGreen+"Exported"+Reset+" %d faces with %d verticies\n", len(Faces), len(Verts))
finished <- -1
}
func main(){
// Verify we were called correctly
if len(os.Args) < 2 {
fmt.Println("Usage: go run objParser.go <OBJ File>");
return
}
files := len(os.Args)
finished := make(chan int)
now := time.Now()
for i := 1; i < files; i++ {
go parseFile(os.Args[i], finished)
}
for i := 1; i < files; i++ {
<- finished
}
fmt.Printf("Parsed %d files in %s\n", files-1, time.Since(now))
}
答案1
得分: 6
你应该为Go设置GOMAXPROCS环境变量，以便将可用处理器的数量设置为最大值。或者在执行时使用GOMAXPROCS函数。
英文:
You should set GOMAXPROCS environment variable for go to the maximum number of usable processors. Or use function GOMAXPROCS at executing time.
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