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分享Java的面包房算法模拟银行排队取号的问题
就是类似那个银行的业务排号系统，正常情况应该是从四个线程各自取号，但是四个线程取出来的都是1，后面的号都取不出来，不知道问题出在哪里。。。求大神指教。。。
代码：
CS.java
import java.util.concurrent.atomic.AtomicIntegerArray;
public class CS extends Thread{
private int id;
AtomicIntegerArray ticket ;
AtomicIntegerArray entering ;
public CS(int id){
this.id = id;
ticket = new AtomicIntegerArray(id);
entering = new AtomicIntegerArray(id);
for(int i = 0; i < id; ++i)
{
ticket.set(i, 0);
entering.set(i, 0);
}
}
public void run(){
while(true){
critical_section();
}
}
public void critical_section(){
for(int i = 0; i < id; i++)
{
entering.set(i, 1);
ticket.set(i, max(ticket) + 1);
entering.set(i, 0);
for(int j = 0; j < ticket.length(); ++j)
{
if(j != i)
{
while(entering.get(i) != 0){}
while(ticket.get(j) != 0 && (ticket.get(j) < ticket.get(i) || (ticket.get(j) == ticket.get(i) && j < i))){}
}
}
System.out.println("Process : " + this.id + " is in its critical section" + "get ticket: " + ticket.get(i) + " ticket length: " + ticket.length() );
unlock(i);
}
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void unlock(int i){
ticket.set(i, 0);
non_critical_section();
}
public void non_critical_section(){
System.out.println("Process : " + this.id + " is in its non-critical section");
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private int max(AtomicIntegerArray turn2) {
// TODO Auto-generated method stub
int max = turn2.get(0);
for(int i = 0; i < this.id; i++){
if(turn2.get(i) > max)
{
max = turn2.get(i);
}
}
return max;
}
}
GreatBakeOff.java
public class GreatBakeOff {
public static void main(String[] args) {
int processes = 4;
CS[] cs = new CS[processes];
for(int i = 0; i < processes; i++){
cs[i] = new CS(i);
}
for(int i = 0; i < processes; i++){
cs[i].start();
}
}
}
输出结果：
代码：
CS.java
import java.util.concurrent.atomic.AtomicIntegerArray;
public class CS extends Thread{
private int id;
AtomicIntegerArray ticket ;
AtomicIntegerArray entering ;
public CS(int id){
this.id = id;
ticket = new AtomicIntegerArray(id);
entering = new AtomicIntegerArray(id);
for(int i = 0; i < id; ++i)
{
ticket.set(i, 0);
entering.set(i, 0);
}
}
public void run(){
while(true){
critical_section();
}
}
public void critical_section(){
for(int i = 0; i < id; i++)
{
entering.set(i, 1);
ticket.set(i, max(ticket) + 1);
entering.set(i, 0);
for(int j = 0; j < ticket.length(); ++j)
{
if(j != i)
{
while(entering.get(i) != 0){}
while(ticket.get(j) != 0 && (ticket.get(j) < ticket.get(i) || (ticket.get(j) == ticket.get(i) && j < i))){}
}
}
System.out.println("Process : " + this.id + " is in its critical section" + "get ticket: " + ticket.get(i) + " ticket length: " + ticket.length() );
unlock(i);
}
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void unlock(int i){
ticket.set(i, 0);
non_critical_section();
}
public void non_critical_section(){
System.out.println("Process : " + this.id + " is in its non-critical section");
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private int max(AtomicIntegerArray turn2) {
// TODO Auto-generated method stub
int max = turn2.get(0);
for(int i = 0; i < this.id; i++){
if(turn2.get(i) > max)
{
max = turn2.get(i);
}
}
return max;
}
}
GreatBakeOff.java
public class GreatBakeOff {
public static void main(String[] args) {
int processes = 4;
CS[] cs = new CS[processes];
for(int i = 0; i < processes; i++){
cs[i] = new CS(i);
}
for(int i = 0; i < processes; i++){
cs[i].start();
}
}
}
输出结果：
...全文
请发表友善的回复…
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Mr_JieLQ 2014-10-30
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[/quote]
可以啊，另外，别忘了结贴
evilsbei 2014-10-30
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碉堡了~牛逼~ 非常感谢~ 能加你个好友不~
evilsbei 2014-10-29
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非常非常感谢u011564172，但是本地显示的结果不对，我想要的是那四个线程每次取号，取出来的都是递增的。 你改的这个调试之后我发现，是每四个线程才会递增一次。
Mr_JieLQ 2014-10-29
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我修改了，请在本地再测试，看看是不是你想要的结果
import java.util.concurrent.atomic.AtomicIntegerArray;
public class CS extends Thread {
private int id;
AtomicIntegerArray ticket;
AtomicIntegerArray entering;
public CS(int id) {
this.id = id;
ticket = new AtomicIntegerArray(id);
entering = new AtomicIntegerArray(id);
for (int i = 0; i < id; ++i) {
ticket.set(i, 0);
entering.set(i, 0);
}
}
public void run() {
while (true) {
critical_section();
}
}
public void critical_section() {
for (int i = 0; i < id; i++) {
entering.set(i, i);
ticket.set(i, max(entering) + 1);
entering.set(i, 0);
for (int j = 0; j < ticket.length(); ++j) {
if (j != i) {
while (entering.get(i) != 0) {
}
while (ticket.get(j) != 0
&& (ticket.get(j) < ticket.get(i) || (ticket.get(j) == ticket
.get(i) && j < i))) {
}
}
}
System.out.println("Process : " + this.id
+ " is in its critical section" + "get ticket: "
+ ticket.get(i) + " ticket length: " + ticket.length());
unlock(i);
}
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void unlock(int i) {
ticket.set(i, 0);
non_critical_section();
}
public void non_critical_section() {
System.out.println("Process : " + this.id
+ " is in its non-critical section");
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private int max(AtomicIntegerArray turn2) {
// TODO Auto-generated method stub
int max = turn2.get(0);
for (int i = 0; i < this.id; i++) {
if (turn2.get(i) > max) {
max = turn2.get(i);
}
}
return max;
}
}
Mr_JieLQ 2014-10-29
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这回应该可以了
import java.util.concurrent.atomic.AtomicIntegerArray;
public class CS extends Thread {
private int id;
static AtomicIntegerArray entering = new AtomicIntegerArray(4);;
static AtomicIntegerArray ticket = new AtomicIntegerArray(4);
public CS(int id) {
this.id = id;
}
public void run() {
while (true) {
critical_section(id);
}
}
public void critical_section(int i) {
entering.set(i, 1);
ticket.set(i, max(ticket) + 1);
entering.set(i, 0);
for (int j = 0; j < ticket.length(); ++j) {
if (j != i) {
while (entering.get(i) != 0) {
}
while (ticket.get(j) != 0
&& (ticket.get(j) < ticket.get(i) || (ticket.get(j) == ticket
.get(i) && j < i))) {
}
}
}
System.out.println("Process : " + this.id
+ " is in its critical section" + "get ticket: "
+ ticket.get(i) + " ticket length: " + ticket.length());
try {
unlock(i);
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void unlock(int i) {
ticket.set(i, 0);
non_critical_section();
}
public void non_critical_section() {
System.out.println("Process : " + this.id
+ " is in its non-critical section");
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private int max(AtomicIntegerArray turn2) {
// TODO Auto-generated method stub
int max = turn2.get(0);
for (int i = 0; i < this.id; i++) {
if (turn2.get(i) > max) {
max = turn2.get(i);
}
}
return max;
}
}
public class GreatBakeOff {
public static void main(String[] args) {
int processes = 4;
CS[] cs = new CS[processes];
for(int i = 0; i < processes; i++){
cs[i] = new CS(i);
}
for(int i = 0; i < processes; i++){
new Thread(cs[i]).start();
}
}
}evilsbei 2014-10-29
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恩恩，这个我昨天出现了这个结果，但是只是一个线程的，所以我加了public void unlock(int i) { ticket.set(i, 0); non_critical_section(); 但是我想启动四个线程达到这样的结果，应该怎么去做呢。
Mr_JieLQ 2014-10-29
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你只启动一个线程看看，你写的这个就是每个线程去一个固定数组取号，不是四个线程去一个数组取号
public class GreatBakeOff {
public static void main(String[] args) {
CS cs = new CS(4);
cs.start();
}
}
Process : 4 is in its critical sectionget ticket: 1 ticket length: 4
Process : 4 is in its non-critical section
Process : 4 is in its critical sectionget ticket: 2 ticket length: 4
Process : 4 is in its non-critical section
Process : 4 is in its critical sectionget ticket: 3 ticket length: 4
Process : 4 is in its non-critical section
Process : 4 is in its critical sectionget ticket: 4 ticket length: 4
Process : 4 is in its non-critical section
