我正在为Java编写Bully算法程序 这是代码：
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
最后我开始接受Address already in use: JVM_Bin的例外
此外，如果我们在提出异常之前检查最新选出的协调员，则在询问is co-ordinator alive?之前选择两次
我确信，当协调员死亡时，我已经提供足够的延迟，以便它不会在两者之间醒来。
当我给予额外的dealy然后程序继续前进，否则它在中间停止
那么为什么必须出现这个问题呢？
我找到了例外的原因
它正在发生，因为如果你在异常消息之前仔细查看输出，它就选择了协调员2ce
每当一个线程被选为协调器时，它就会在端口12345打开一个ServerSocket
因为它发生了2ce，所以可能会抛出异常
但是我不明白......为什么选择2ce？
答案 0 :(得分：3)
在这两种情况下，您的错误消息是“地址已在使用中：JVM_Bind”。
此消息通常是java.net.BindException的一部分，当您尝试创建/打开Socket并且端口已在使用中时，会抛出该消息。在这种情况下，您可能尝试打开或创建两次相同的套接字。
这可能发生，因为在打开和关闭套接字之间，异常会停止调用socket.close（）。在这种情况下，当您为选举领导者创建套接字时，但由于主机被“崩溃”，因此抛出异常，因此永远不会调用close（）。
我认为你需要添加一行
electionMessage.close（）;发送消息的这部分的catch子句。
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) {
//Add close here
System.out.println("Process[" + this.process.getPid() + "] -> Process[" + i + "] did not respond to election message");
}
另外，我建议将所有其他相关的catch条款添加到其他地方，如果它在其他地方发生这种情况，并且始终是避免相关问题的良好做法。 我还建议明确指出你想要在每个地方捕获哪些例外，这样你就不会被其他陷阱所困扰。
我希望这是一个很好的起点。
我认为您“锁定”线程的方式存在问题。您依靠布尔标志来告诉您已达到代码中的特定点。但布尔标志本身不是在同步块中控制的，也不是代码上的任何其他锁。因此，多个线程可以通过锁定并导致意外事件，例如多次尝试打开同一个套接字。
您正在使用带锁的对象的代码
if (Election.isMessageFlag()) {
synchronized (Election.lock) {
Election.lock.wait();
}
}
Election.setMessageFlag(true);
if (Election.isElectionFlag()) {
// Do Stuff
// Open/close Sockets etc
}
Election.setMessageFlag(false);
synchronized (Election.lock) {
Election.lock.notifyAll();
}
这是多个线程可以在设置标志之前传递第一个if语句（在下一行！），以使后续线程等待。
但是，如果您使用ReentrantLock，则应使用以下代码：
lock.lock(); // block until condition holds
try {
// Do Stuff
// OPen CLose Sockets etc
} finally {
lock.unlock()
}
显然，你可能仍然需要设置一些标志来说明选举是否正在进行，但要确保用真正的锁定来保护正在运行的代码，例如： ReentrantLock，或在适当的同步块内。
希望这有帮助
答案 1 :(得分：0)
在参考上述所有评论后，我发布的代码完全正确，以便其他人可以参考 欢迎代码中的任何改进建议......
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 (NullPointerException e) {
System.out.println(e.getMessage());
}
for (int i = 0; i < total_processes; i++) {
new Thread(t[i]).start();//start every thread
}
}
}
package newbully;
import java.util.concurrent.locks.ReentrantLock;
public class Election {
public static ReentrantLock pingLock = new ReentrantLock();
public static ReentrantLock electionLock = new ReentrantLock();
private static boolean electionFlag = false; //By default no election is going on
private static boolean pingFlag = true; //By default I am allowed to ping
public static Process electionDetector;
public static Process getElectionDetector() {
return electionDetector;
}
public static void setElectionDetector(Process electionDetector) {
Election.electionDetector = electionDetector;
}
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;
import java.util.*;
import java.io.*;
import java.net.*;
public class RunningThread implements Runnable {
private Process process;
private int total_processes;
private static boolean messageFlag[];
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];
RunningThread.messageFlag = new boolean[total_processes];
for (int i = 0; i < total_processes; i++) {
RunningThread.messageFlag[i] = false;
}
}
synchronized private void recovery() {
while (Election.isElectionFlag());//if election is going on then wait
System.out.println("Process[" + this.process.getPid() + "]: -> Recovered from Crash");
//Find current co-ordinator.
try {
Election.pingLock.lock();
Election.setPingFlag(false);
Socket outgoing = new Socket(InetAddress.getLocalHost(), 12345);
Scanner scan = new Scanner(outgoing.getInputStream());
PrintWriter out = new PrintWriter(outgoing.getOutputStream(), true);
System.out.println("Process[" + this.process.getPid() + "]:-> Who is the co-ordinator?");
out.println("Who is the co-ordinator?");
out.flush();
String pid = scan.nextLine();
String priority = scan.nextLine();
if (this.process.getPriority() > Integer.parseInt(priority)) { //Bully Condition
out.println("Resign");
out.flush();
System.out.println("Process[" + this.process.getPid() + "]: Resign -> Process[" + pid + "]");
String resignStatus = scan.nextLine();
if (resignStatus.equals("Successfully Resigned")) {
this.process.setCoOrdinatorFlag(true);
sock[this.process.getPid() - 1] = new ServerSocket(10000 + this.process.getPid());
System.out.println("Process[" + this.process.getPid() + "]: -> Bullyed current co-ordinator Process[" + pid + "]");
}
} else {
out.println("Don't Resign");
out.flush();
}
Election.pingLock.unlock();
return;
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
}
synchronized private void pingCoOrdinator() {
try {
Election.pingLock.lock();
if (Election.isPingFlag()) {
System.out.println("Process[" + this.process.getPid() + "]: Are you alive?");
Socket outgoing = new Socket(InetAddress.getLocalHost(), 12345);
outgoing.close();
}
} catch (Exception ex) {
Election.setPingFlag(false);
Election.setElectionFlag(true);
Election.setElectionDetector(this.process);
//Initiate Election
System.out.println("process[" + this.process.getPid() + "]: -> Co-Ordinator is down\n" + "process[" + this.process.getPid() + "]: ->Initiating Election");
} finally {
Election.pingLock.unlock();
}
}
private void executeJob() {
int temp = r.nextInt(20);
for (int i = 0; i <= temp; i++) {
try {
Thread.sleep((temp + 1) * 100);
} catch (InterruptedException e) {
System.out.println("Error Executing Thread:" + process.getPid());
System.out.println(e.getMessage());
}
}
}
synchronized private boolean sendMessage() {
boolean response = false;
try {
Election.electionLock.lock();
if (Election.isElectionFlag() && !RunningThread.isMessageFlag(this.process.getPid() - 1) && this.process.priority >= Election.getElectionDetector().getPriority()) {
for (int 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 (IOException ex) {
System.out.println("Process[" + this.process.getPid() + "] -> Process[" + i + "] did not respond to election message");
} catch (Exception ex) {
System.out.println(ex.getMessage());
}
}
this.setMessageFlag(true, this.process.getPid() - 1);//My message sending is done
Election.electionLock.unlock();
return response;
} else {
throw new Exception();
}
} catch (Exception ex1) {
Election.electionLock.unlock();
return true;
}
}
public static boolean isMessageFlag(int index) {
return RunningThread.messageFlag[index];
}
public static void setMessageFlag(boolean messageFlag, int index) {
RunningThread.messageFlag[index] = messageFlag;
}
synchronized private void serve() {
try {
boolean done = false;
Socket incoming = null;
ServerSocket s = new ServerSocket(12345);
Election.setPingFlag(true);
int temp = this.r.nextInt(5) + 5;// min 5 requests and max 10 requests
for (int counter = 0; counter < temp; counter++) {
incoming = s.accept();
if (Election.isPingFlag()) {
System.out.println("Process[" + this.process.getPid() + "]:Yes");
}
Scanner scan = new Scanner(incoming.getInputStream());
PrintWriter out = new PrintWriter(incoming.getOutputStream(), true);
while (scan.hasNextLine() && !done) {
String line = scan.nextLine();
if (line.equals("Who is the co-ordinator?")) {
System.out.println("Process[" + this.process.getPid() + "]:-> " + this.process.getPid());
out.println(this.process.getPid());
out.flush();
out.println(this.process.getPriority());
out.flush();
} else if (line.equals("Resign")) {
this.process.setCoOrdinatorFlag(false);
out.println("Successfully Resigned");
out.flush();
incoming.close();
s.close();
System.out.println("Process[" + this.process.getPid() + "]:-> Successfully Resigned");
return;
} else if (line.equals("Don't Resign")) {
done = true;
}
}
}
//after serving 5-10 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(15000);//(this.r.nextInt(10) + 1) * 10000);//going down
recovery();
} catch (Exception 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();
//Do Election
if (Election.isElectionFlag()) {
if (!sendMessage()) {//elect self as co-ordinator
Election.setElectionFlag(false);//Election is Done
System.out.println("New Co-Ordinator: Process[" + this.process.getPid() + "]");
this.process.setCoOrdinatorFlag(true);
for (int i = 0; i < total_processes; i++) {
RunningThread.setMessageFlag(false, i);
}
break;
}
}
}
}
}
}
}
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;
}
}