Using semaphores, provide codes for processes X1, X2, X3, X4 and X5 in the following
synchronization problem. Each process has a special (synchronization) point in its code.
• Process X1 may cross its synchronization point unconditionally,
• Process X4 has to wait for processes X3 and X1 to cross or reach their synchronization points,
and only then X4 may cross its synchronization point,
• Process X2 has to wait for process X1 to cross or reach its synchronization point, and only then
X2 may cross its synchronization point,
• Process X3 has to wait for process X4 to cross or reach its synchronization point, and only then
X3 may cross its synchronization point,
• Process X5 has to wait for processes X1, X3 and X4 to cross their synchronization points, and
only then X5 may cross its synchronization point.
Assume that each process will cross its synchronization point only once.
Solution
/*In the above specified conditions the process X4 depedns on completion of synchronization of
X3 and X1.
whereas the X3 depends on synchronisation of X4. This may create deadlock.
*/
package semaphoretest;
import java.util.concurrent.Semaphore;
public class SemaphoreTest implements Runnable {
Semaphore binary = new Semaphore(1);
@Override
public void run() {
boolean flg=false;
System.out.println(\"Started\");
while(!flg) {
System.out.println(\"Thread is running\");
}
System.out.println(\"Stopped\");
}
public static void main(String args[]) {
final SemaphoreTest test = new SemaphoreTest();
Thread t1=new Thread(){
@Override
public void run(){
test.mutualExclusion();
}
};
Thread t2=new Thread(){
@Override
public void run(){
test.mutualExclusion();
}
};
Thread t3=new Thread(){
@Override
public void run(){
test.mutualExclusion();
}
};
Thread t4=new Thread(){
@Override
public void run(){
test.mutualExclusion();
}
};
Thread t5=new Thread(){
@Override
public void run(){
test.mutualExclusion();
}
};
t1.start();
t2.start();
t3.start();
t4.start();
t5.start();
}
private void mutualExclusion() {
try {
binary.acquire();
//mutual exclusive region
String tn=Thread.currentThread().getName();
String numberOnly= tn.replaceAll(\"[^0-9]\", \"\");
int num=Integer.parseInt(numberOnly)+1;
System.out.println(\"Thread \"+num + \" is running\");
Thread.sleep(100);
} catch (InterruptedException ie) {
ie.printStackTrace();
} finally {
binary.release();
String tn=Thread.currentThread().getName();
String numberOnly= tn.replaceAll(\"[^0-9]\", \"\");
int num=Integer.parseInt(numberOnly)+1;
System.out.println(\"Thread \"+num + \" completed...!!!\");
}
}
}.
What are some considerations when entering data into SPSSSoluti.pdf
1. What are some considerations when entering data into SPSS?
Solution
SPSS sets out its data in a spreadsheet-like manner. The principle of entering data in almost all
cases in SPSS Statistics is to enter the unique case in a new row. A case is the "object" which
you are measuring in someway. Usually, a case is an individual, but it can also be a commercial
product or a biological cell .
