Possible Duplicate:
Why my golang lock free queue always stuck there?
Here's my whole source code :
package main
import (
"sync/atomic"
"unsafe"
"sync"
"fmt"
"time"
"runtime"
)
const (
MAX_DATA_SIZE = 100
)
// lock free queue
type Queue struct {
head unsafe.Pointer
tail unsafe.Pointer
}
// one node in queue
type Node struct {
val interface{}
next unsafe.Pointer
}
// constructor
func New() (q *Queue) {
queue := new(Queue)
queue.head = unsafe.Pointer(new(Node))
queue.tail = queue.head
return queue
}
// queue functions
func (self *Queue) enQueue(val interface{}) {
newValue := unsafe.Pointer(&Node{val: val, next: nil})
var tail,next unsafe.Pointer
for {
tail = self.tail
next = ((*Node)(tail)).next
if atomic.CompareAndSwapPointer(&next, nil, newValue) {
atomic.CompareAndSwapPointer(&self.tail, tail, newValue)
break
}else{
for next != nil {
tail = next
}
}
}
}
func (self *Queue) deQueue() (val interface{}, success bool){
var head,next unsafe.Pointer
for {
head = self.head
next = ((*Node)(head)).next
if next == nil {
return nil, false
}else {
if atomic.CompareAndSwapPointer(&(self.head), head, next) {
val = ((*Node)(next)).val
return val, true
}
}
}
return nil, false
}
func main() {
//runtime.GOMAXPROCS(runtime.NumCPU())
fmt.Println(runtime.GOMAXPROCS(-1))
var wg sync.WaitGroup
wg.Add(20)
queue := New()
for i := 0; i < 10; i++ {
go func() {
defer wg.Done()
for j := 0; j < MAX_DATA_SIZE; j++ {
t := time.Now()
fmt.Println("enqueue111")
fmt.Println("enq = ", t)
fmt.Println("enqueue222")
queue.enQueue(t)
}
}()
}
for i := 0; i < 10; i++ {
go func() {
ok := false
var val interface{}
defer wg.Done()
for j := 0; j < MAX_DATA_SIZE; j++ {
val,ok = queue.deQueue()
for !ok {
val,ok = queue.deQueue()
}
fmt.Println("deq = ",val)
}
}()
}
wg.Wait()
}
The code is stucked at fmt.Println("enq = ", t) but i don't know why, it's so weird.
