我正在为 Java 中的 Bully 算法编写程序
代码如下:
package newbully;
public class NewBully {
public static void main(String[] args) {
int total_processes = 6;
RunningThread[] t = new RunningThread[total_processes];
for (int i = 0; i < total_processes; i++) {
t[i] = new RunningThread(new Process(i+1, i+1), total_processes);//passing process id, priority, total no. of processes to running thread
}
try {
Election.initialElection(t);
} catch (Exception e) {
System.out.println("Possibly you are using null references in array");
}
for (int i = 0; i < total_processes; i++) {
new Thread(t[i]).start();//start every thread
}
}
}
package newbully;
import java.util.*;
import java.io.*;
import java.net.*;
public class RunningThread implements Runnable {
private Process process;
private int total_processes;
ServerSocket[] sock;
Random r;
public Process getProcess() {
return process;
}
public void setProcess(Process process) {
this.process = process;
}
public RunningThread(Process process, int total_processes) {
this.process = process;
this.total_processes = total_processes;
this.r = new Random();
this.sock = new ServerSocket[total_processes];
}
synchronized private void recovery() {
System.out.println("Process[" + this.process.getPid() + "]: -> Recovered from Crash");
//Find current co-ordinator.
}
synchronized private void pingCoOrdinator() {
try {
if (Election.isPingFlag()) {
synchronized (Election.lock) {
Election.lock.wait();
}
}
if (!Election.isElectionFlag()) {
Election.setPingFlag(true);
System.out.println("Process[" + this.process.getPid() + "]: Are you alive?");
Socket outgoing = new Socket(InetAddress.getLocalHost(), 12345);
outgoing.close();
Election.setPingFlag(false);
synchronized (Election.lock) {
Election.lock.notifyAll();
}
}
} catch (Exception ex) {
//Initiate Election
System.out.println("process[" + this.process.getPid() + "]: -> Co-Ordinator is down\nInitiating Election");
Election.setElectionFlag(true);
Election.setPingFlag(false);
synchronized (Election.lock) {
Election.lock.notifyAll();
}
}
}
synchronized private void executeJob() {
int temp = r.nextInt(20);
for (int i = 0; i <= temp; i++) {
try {
Thread.sleep(700);
} catch (InterruptedException e) {
System.out.println("Error Executing Thread:" + process.getPid());
System.out.println(e.getMessage());
}
}
}
synchronized private boolean sendMessage() {
boolean response = false;
int i = 0;
try {
if (Election.isMessageFlag()) {
synchronized (Election.lock) {
Election.lock.wait();
}
}
Election.setMessageFlag(true);
if (Election.isElectionFlag()) {
for (i = this.process.getPid() + 1; i <= this.total_processes; i++) {
try {
Socket electionMessage = new Socket(InetAddress.getLocalHost(), 10000 + i);
System.out.println("Process[" + this.process.getPid() + "] -> Process[" + i + "] responded to election message successfully");
electionMessage.close();
response = true;
} catch (Exception ex) {
System.out.println("Process[" + this.process.getPid() + "] -> Process[" + i + "] did not respond to election message");
}
}
}
Election.setMessageFlag(false);
synchronized (Election.lock) {
Election.lock.notifyAll();
}
} catch (Exception ex1) {
System.out.println(ex1.getMessage());
}
return response;
}
synchronized private void serve() {
try {
//service counter
Socket incoming = null;
ServerSocket s = new ServerSocket(12345);
for (int counter = 0; counter < 10; counter++) {
incoming = s.accept();
System.out.println("Process[" + this.process.getPid() + "]:Yes");
Scanner scan = new Scanner(incoming.getInputStream());
PrintWriter out = new PrintWriter(incoming.getOutputStream(), true);
if (scan.hasNextLine()) {
if (scan.nextLine().equals("Who is the co-ordinator?")) {
System.out.print("Process[" + this.process.getPid() + "]:");
out.println(this.process);
}
}
}
//after serving 10 requests go down for random time
this.process.setCoOrdinatorFlag(false);
this.process.setDownflag(true);
try {
incoming.close();
s.close();
sock[this.process.getPid() - 1].close();
Thread.sleep((this.r.nextInt(10) + 1) * 1000000);//going down
recovery();
} catch (InterruptedException e) {
System.out.println(e.getMessage());
}
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
}
@Override
public void run() {
try {
sock[this.process.getPid() - 1] = new ServerSocket(10000 + this.process.getPid());
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
while (true) {
if (process.isCoOrdinatorFlag()) {
//serve other processes
serve();
} else {
while (true) {
//Execute some task
executeJob();
//Ping the co-ordinator
pingCoOrdinator();
if (Election.isElectionFlag()) {
if (!sendMessage()) {//elect self as co-ordinator
System.out.println("New Co-Ordinator: Process[" + this.process.getPid() + "]");
this.process.setCoOrdinatorFlag(true);
Election.setElectionFlag(false);
break;
}
}
}
}
}
}
}
package newbully;
public class Election {
private static boolean pingFlag = false;
private static boolean electionFlag = false;
private static boolean messageFlag = false;
public static final Object lock = new Object();
public static boolean isMessageFlag() {
return messageFlag;
}
public static void setMessageFlag(boolean messageFlag) {
Election.messageFlag = messageFlag;
}
public static boolean isPingFlag() {
return pingFlag;
}
public static void setPingFlag(boolean pingFlag) {
Election.pingFlag = pingFlag;
}
public static boolean isElectionFlag() {
return electionFlag;
}
public static void setElectionFlag(boolean electionFlag) {
Election.electionFlag = electionFlag;
}
public static void initialElection(RunningThread[] t) {
Process temp = new Process(-1, -1);
for (int i = 0; i < t.length; i++) {
if (temp.getPriority() < t[i].getProcess().getPriority()) {
temp = t[i].getProcess();
}
}
t[temp.pid - 1].getProcess().CoOrdinatorFlag = true;
}
}
package newbully;
public class Process {
int pid;
boolean downflag,CoOrdinatorFlag;
public boolean isCoOrdinatorFlag() {
return CoOrdinatorFlag;
}
public void setCoOrdinatorFlag(boolean isCoOrdinator) {
this.CoOrdinatorFlag = isCoOrdinator;
}
int priority;
public boolean isDownflag() {
return downflag;
}
public void setDownflag(boolean downflag) {
this.downflag = downflag;
}
public int getPid() {
return pid;
}
public void setPid(int pid) {
this.pid = pid;
}
public int getPriority() {
return priority;
}
public void setPriority(int priority) {
this.priority = priority;
}
public Process() {
}
public Process(int pid, int priority) {
this.pid = pid;
this.downflag = false;
this.priority = priority;
this.CoOrdinatorFlag = false;
}
}
这是输出:
//--When delay in executeJob() method is 100
Process[4]: Are you alive?
Process[6]:Yes
Process[4]: Are you alive?
Process[6]:Yes
Process[3]: Are you alive?
Process[6]:Yes
Process[5]: Are you alive?
Process[6]:Yes
Process[1]: Are you alive?
Process[6]:Yes
Process[4]: Are you alive?
Process[6]:Yes
Process[3]: Are you alive?
Process[6]:Yes
Process[3]: Are you alive?
Process[6]:Yes
Process[2]: Are you alive?
Process[6]:Yes
Process[5]: Are you alive?
Process[6]:Yes
Process[1]: Are you alive?
process[1]: -> Co-Ordinator is down
Initiating Election
Process[1] -> Process[2] responded to election message successfully
Process[1] -> Process[3] responded to election message successfully
Process[1] -> Process[4] responded to election message successfully
Process[1] -> Process[5] responded to election message successfully
Process[1] -> Process[6] did not respond to election message
Process[2] -> Process[3] responded to election message successfully
Process[3] -> Process[4] responded to election message successfully
Process[4] -> Process[5] responded to election message successfully
Process[2] -> Process[4] responded to election message successfully
Process[2] -> Process[5] responded to election message successfully
Process[3] -> Process[5] responded to election message successfully
Process[5] -> Process[6] did not respond to election message
New Co-Ordinator: Process[5]
New Co-Ordinator: Process[1]
Address already in use: JVM_Bind
Address already in use: JVM_Bind
Address already in use: JVM_Bind
//--When delay in executeJob() method is 700
Process[3]: Are you alive?
Process[6]:Yes
Process[5]: Are you alive?
Process[6]:Yes
Process[2]: Are you alive?
Process[1]: Are you alive?
Process[6]:Yes
Process[6]:Yes
Process[5]: Are you alive?
Process[1]: Are you alive?
Process[6]:Yes
Process[6]:Yes
Process[4]: Are you alive?
Process[6]:Yes
Process[3]: Are you alive?
Process[6]:Yes
Process[2]: Are you alive?
Process[6]:Yes
Process[1]: Are you alive?
Process[6]:Yes
Process[4]: Are you alive?
process[4]: -> Co-Ordinator is down
Initiating Election
Process[4] -> Process[5] responded to election message successfully
Process[4] -> Process[6] did not respond to election message
Process[5] -> Process[6] did not respond to election message
New Co-Ordinator: Process[5]
Process[1]: Are you alive?
Process[5]:Yes
Process[1]: Are you alive?
Process[5]:Yes
Process[3]: Are you alive?
Process[5]:Yes
Process[2]: Are you alive?
Process[5]:Yes
Process[1]: Are you alive?
Process[5]:Yes
Process[4]: Are you alive?
Process[5]:Yes
Process[2]: Are you alive?
Process[5]:Yes
Process[4]: Are you alive?
Process[5]:Yes
Process[3]: Are you alive?
Process[5]:Yes
Process[3]: Are you alive?
Process[5]:Yes
Process[2]: Are you alive?
process[2]: -> Co-Ordinator is down
Initiating Election
Process[2] -> Process[3] responded to election message successfully
Process[2] -> Process[4] responded to election message successfully
Process[2] -> Process[5] did not respond to election message
Process[2] -> Process[6] did not respond to election message
Process[3] -> Process[4] responded to election message successfully
Process[3] -> Process[5] did not respond to election message
Process[3] -> Process[6] did not respond to election message
Process[1] -> Process[2] responded to election message successfully
Process[1] -> Process[3] responded to election message successfully
Process[1] -> Process[4] responded to election message successfully
Process[1] -> Process[5] did not respond to election message
Process[1] -> Process[6] did not respond to election message
Process[2] -> Process[3] responded to election message successfully
Process[2] -> Process[4] responded to election message successfully
Process[2] -> Process[5] did not respond to election message
Process[2] -> Process[6] did not respond to election message
Process[4] -> Process[5] did not respond to election message
Process[4] -> Process[6] did not respond to election message
New Co-Ordinator: Process[4]
Process[3]: Are you alive?
Process[4]:Yes
Process[3]: Are you alive?
Process[4]:Yes
Process[1]: Are you alive?
Process[4]:Yes
Process[2]: Are you alive?
Process[4]:Yes
Process[1]: Are you alive?
Process[4]:Yes
Process[2]: Are you alive?
Process[4]:Yes
Process[2]: Are you alive?
Process[4]:Yes
Process[2]: Are you alive?
Process[4]:Yes
Process[3]: Are you alive?
Process[4]:Yes
Process[1]: Are you alive?
Process[4]:Yes
Process[3]: Are you alive?
process[3]: -> Co-Ordinator is down
Initiating Election
Process[3] -> Process[4] did not respond to election message
Process[3] -> Process[5] did not respond to election message
Process[3] -> Process[6] did not respond to election message
New Co-Ordinator: Process[3]
New Co-Ordinator: Process[2]
Address already in use: JVM_Bind
Address already in use: JVM_Bind
Address already in use: JVM_Bind
Address already in use: JVM_Bind
Address already in use: JVM_Bind
最后我开始得到例外Address already in use: JVM_Bin
。
另外,如果我们在thow例外前与OUPUT的最新选举协调员联系,它选择了两次,然后问is co-ordinator alive?
我确定协调员死亡时,我已经提供了足够的延迟,以免它介于两者之间。
当我给予额外的交易时,程序会继续进行,否则它会在中间停止。
那么为什么一定会出现这个问题呢?
我找到了异常的原因
它正在发生,因为如果你在异常消息之前仔细查看输出,它已经选择了协调器 2ce。
每当一个线程被选为协调者时,它都会在端口 12345 上打开一个 ServerSocket。
由于它发生在 2ce,它可能会引发异常。
但我不明白......为什么它选择了2ce?