我已经编写了解决餐饮哲学家问题的算法。但它给予stackoverflow异常。任何人都可以帮助我。解决一些问题。这是使用多线程的餐饮哲学家问题。我在哪里用ArrayList来存放筷子和盘子。
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package com.intech.DiningPhilosopherProblem;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import javax.annotation.processing.Processor;
public class MyPhilosophers {
/**
* @param args
*/
static int noOfP = ((Runtime.getRuntime().availableProcessors() * 2) + (1));
// Runtime.getRuntime().availableProcessors();
public static void main(String[] args) throws InterruptedException {
MyPhilosophersChopstick myPs = new MyPhilosophersChopstick(noOfP);
ExecutorService execserv = Executors.newFixedThreadPool(5);
for (int i = 0; i < 500; i++) {
Thread.sleep(200);
execserv.execute(myPs);
}
// execserv.shutdown(); // Disable new tasks from being submitted
try {
// Wait a while for existing tasks to terminate
if (!execserv.awaitTermination(600, TimeUnit.SECONDS)) {
execserv.shutdownNow(); // Cancel currently executing tasks
// Wait a while for tasks to respond to being cancelled
if (!execserv.awaitTermination(600, TimeUnit.SECONDS))
System.err.println("Pool did not terminate");
}
}
catch (InterruptedException ie) {
// (Re-)Cancel if current thread also interrupted
execserv.shutdownNow();
// Preserve interrupt status
Thread.currentThread().interrupt();
}
}
}
`
package com.intech.DiningPhilosopherProblem;
public class MyPhilosophersChopstick implements Runnable {
volatile int eatingturns =0;
volatile int allowedeatingturns =200;
volatile int noOfChopsticks=0;
volatile int[] arrayChopsticks;
volatile int i=0;
public MyPhilosophersChopstick(int chopsticks)
{
arrayChopsticks=new int[chopsticks];
this.noOfChopsticks=chopsticks;
for (int i = 0; i < noOfChopsticks; i++)
{
arrayChopsticks[i]=0;
}
System.out.println("noOfChopsticks"+noOfChopsticks);
System.out.println("arrayChopsticks.length"+arrayChopsticks.length);
}
public void run()
{ System.out.println("run count"+ i++);
while(eatingturns<allowedeatingturns)
{
String s=Thread.currentThread().getName();
char c=s.charAt(s.length()-1); //c = which thread thread no 1, thread no 2, thread no 3, thread no 4. It denotes to which philosopher in char
int j=(int)c; //j = which thread thread no 1, thread no 2, thread no 3, thread no 4. It denotes to which philosopher in int where 0=49 , 1=50.... and so on
System.out.println("j"+j);
if(c>noOfChopsticks)
System.out.println("c"+c);
j=j-49; //converting char in to int digits as value for 0=49, 1=50.... and so on
System.out.println("j"+j);
System.out.println( Thread.currentThread().getName()+"Thinking-------------"+j);
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
hungary(j);
}
}
public void hungary(int i)
{
//System.out.println( Thread.currentThread().getName()+"Inside hungary()-------------"+i);
//else nothing
boolean a=eat(i);
if(a==true)
System.out.println(Thread.currentThread().getName()+"Eating-------------"+i+""+arrayChopsticks[i]);
synchronized (this){
eatingturns++;
}
a=doneEating(i);
}
private boolean eat(int i) {
// TODO Auto-generated method stub
// System.out.println(
// Thread.currentThread().getName()+"Inside eat()-------------"+i);
boolean a;
boolean b;
if (i == 0) {
synchronized (this) {
if ((a = pickchopstickRight(i))
&& (b = pickchopstickLeft(arrayChopsticks.length - 1))) {
return true;
}
keepChopstickRight(i); // if right chopstick not available
return false;
}
} else {
if ((a = pickchopstickRight(i)) && (b = pickchopstickLeft(i - 1))) {
return true;
}
keepChopstickRight(i); // if right chopstick not available
return false;
}
}
private boolean doneEating(int i) {
// TODO Auto-generated method stub
//System.out.println( Thread.currentThread().getName()+"Inside wantToThink()-------------"+i);
boolean a;
boolean b;
if(i==0){
//synchronized (this)
{
a=keepChopstickLeft(arrayChopsticks.length-1);
b=keepChopstickRight(i);
}
}
else
{
a=keepChopstickLeft(i-1);
b=keepChopstickRight(i); //pandey
}
if(a&&b)
{
return true;
}
return false;
}
private boolean keepChopstickLeft(int i) {
//System.out.println( Thread.currentThread().getName()+"INSIDE keepchopstick Left -------------"+i);
if(arrayChopsticks[i]==1)
{
System.out.println( Thread.currentThread().getName()+"Keeping down Left chopstick -------------"+i+""+arrayChopsticks[i]);
arrayChopsticks[i]=0;
return true;
}
return false;
}
private boolean keepChopstickRight(int i)
{
System.out.println( Thread.currentThread().getName()+"INSIDE keepchopstick Right -------------"+i+""+arrayChopsticks[i]);
if(arrayChopsticks[i]==1)
{
System.out.println( Thread.currentThread().getName()+"Keeping down Right chopstick -------------"+i+""+arrayChopsticks[i]);
arrayChopsticks[i]=0;
run(); //goest to run
}
return false;
}
private boolean pickchopstickLeft(int i)
{
//System.out.println( Thread.currentThread().getName()+"INSIDE pickchopstickLEFT -------------"+i);
if(arrayChopsticks[i]==0)
{
System.out.println( Thread.currentThread().getName()+"picking up chopstick Left -------------"+i+""+arrayChopsticks[i]);
arrayChopsticks[i]=1;
return true;
}
return false;
}
private boolean pickchopstickRight(int i) {
//System.out.println( Thread.currentThread().getName()+"INSIDE pickchopstickRight -------------"+i);
if(arrayChopsticks[i]==0)
{
System.out.println( Thread.currentThread().getName()+"picking up chopstick Right -------------"+i+""+arrayChopsticks[i]);
arrayChopsticks[i]=1;
return true;
}
return false;
}
}
答案 0 :(得分：1)
可能是程序中存在内存泄漏，或者您必须使用-xMx -Xms来增加堆和堆栈大小