Practical No: 1 Aim: Demonstrate round - robin scheduling using threads.

Transcription

1 Practical No: 1 Aim: Demonstrate round - robin scheduling using threads. Source Code: RR.java import java.io.*; class job implements Runnable int process_id, no_of_instr,time_quantum; Thread t; job(int pid, int instr, int tq) process_id = pid; no_of_instr = instr; time_quantum = tq; t = new Thread(this); t.start(); public void run() try for(int i=1; i<=no_of_instr; i++) System.out.println("Executing instr no " + i + " of process " + process_id); Thread.sleep(time_quantum); System.out.println("Job " + process_id + " is over");

2 catch(interruptedexception e) System.out.println("The job has been interrupted..."); class RR public static void main(string args[]) try int process_id=100, time_quantum = 100; BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("Enter a user process starting number:"); process_id = Integer.parseInt(br.readLine()); System.out.println("Enter a time quantum(in millis):"); time_quantum = Integer.parseInt(br.readLine()); job j1 = new job(process_id, 10, time_quantum); job j2 = new job(++process_id, 6, time_quantum); job j3 = new job(++process_id, 8, time_quantum); catch(exception e) System.out.println("Some process failed to complete..."); System.out.println("Plz contact system admin...");

3 Output:

4 Practical No: 2 Aim: Demonstrate Priority scheduling using threads. Source Code: Priority.java import java.io.*; class job implements Runnable int process_id, no_of_instr,priority_value, time_quantum; Thread t; job(int pid, int instr, int prio, int tq) process_id = pid; no_of_instr = instr; time_quantum = tq; priority_value = prio; t = new Thread(this); t.setpriority(priority_value); t.start(); public void run() try for(int i=1; i<=no_of_instr; i++) process_id); System.out.println("Executing instr no " + i + " of process " + Thread.sleep(time_quantum);

5 System.out.println("Job " + process_id + " is over"); catch(interruptedexception e) System.out.println("The job has been interrupted..."); class Priority public static void main(string args[]) try int process_id=100, time_quantum = 100; BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("Enter a user process starting number:"); process_id = Integer.parseInt(br.readLine()); System.out.println("Enter a time quantum(in millis):"); time_quantum = Integer.parseInt(br.readLine()); job j1 = new job(++process_id, 8, 9, time_quantum); job j2 = new job(++process_id, 8, 1, time_quantum); job j3 = new job(++process_id, 8, 2, time_quantum); catch(exception e) System.out.println("Some process failed to complete...");

6 System.out.println("Plz contact system admin..."); Output:

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8 Practical No: 3 Aim: Calculate Turn - around time for any scheduling algorithm. Source Code: turn_around_time.java import java.io.*; import java.util.*; //class job represents os process //each job has some number of instructions //OS assigns process id and time quantum class job implements Runnable int process_id, no_of_instr,time_quantum; long millis; Thread t; job(int pid, int instr, int tq) millis = System.currentTimeMillis(); process_id = pid; no_of_instr = instr; time_quantum = tq; t = new Thread(this); t.start(); public void run() try for(int i=1; i<=no_of_instr; i++)

9 process_id); System.out.println("Executing instr no " + i + " of process " + Thread.sleep(time_quantum); millis = System.currentTimeMillis() - millis; turn_around_time.millitime = turn_around_time.millitime + millis; System.out.println("Job " + process_id + " with " + no_of_instr + " instructions has completed in " + millis + " milliseconds"); catch(interruptedexception e) class turn_around_time static long millitime = 0; System.out.println("The job has been interrupted..."); static int process_id=100, time_quantum = 100; public static void main(string args[]) try BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("Enter a user process starting number:"); process_id = Integer.parseInt(br.readLine()); System.out.println("Enter a time quantum(in millis):"); time_quantum = Integer.parseInt(br.readLine());

10 job j1 = new job(process_id, 15, time_quantum); job j2 = new job(++process_id, 7, time_quantum); job j3 = new job(++process_id, 10, time_quantum); Thread mainthread = Thread.currentThread(); mainthread.sleep(3000); System.out.println("Average turn around time = " + (millitime)/3.0f); catch(exception e) System.out.println("Some process failed to complete..."); System.out.println("Plz contact system admin..."); Output:

11 Practical No: 4 Aim: Demonstrate the concept of synchronized access to shared resource. Source Code: //Demonstrate the concept of synchronized access to shared resource class room public synchronized void takeslecture(string name) throws InterruptedException System.out.println(name + " enters..."); Thread.sleep(250); System.out.println(name + " starts lecture..."); Thread.sleep(500); System.out.println(name + " exits..."); Thread.sleep(250); class lecturer implements Runnable String name; room r; Thread t; lecturer(string n,room r) name = n; t = new Thread(this, n); this.r = r; public void start()

12 t.start(); public void run() try r.takeslecture(name); catch(interruptedexception e) System.out.println(name + " operation interrupted..."); class synch_access public static void main(string args[]) room r = new room(); lecturer ABC= new lecturer("abc Sir",r); lecturer MNO= new lecturer("mno Madam",r); lecturer PQR = new lecturer("pqr",r); ABC.start(); MNO.start(); PQR.start();

13 Output:

14 Practical No: 5 Aim: Demonstrate any 1 of deadlock-avoidance algorithm Source Code: deadlock_avoidance.java import java.io.*; class Banker int avail[]; int max[][] = 3,2,2,1, 8,12,0,0, 2,1,0,0, 4,3,0,0, 2,0,3,1; int alloc[][] = 1,1,1,0, 2,1,0,0, 1,0,0,0, 2,1,0,0, 1,0,0,0; int need[][]; int m,n; Banker() m = 4; n = 5; avail = new int[4]; avail[0] = 16; // Number of Registers avail[1] = 50; // Number of Files avail[2] = 5; // Number of Ports avail[3] = 2; // Number of Printer need = new int[5][4]; for(int i=0;i<5; i++) for(int j=0;j<4; j++) need[i][j] = max[i][j] - alloc[i][j]; boolean issafe()

15 int work[] = new int[m]; boolean finish[] = new boolean[n]; for(int i=0 ;i<m; i++) work[i] = avail[i]; for(int i=0 ;i<n; i++) finish[i] = false; for(int i=0; i<n; i++) if(finish[i]==false) boolean incomplete=false; for(int j=0;j<m; j++) if(need[i][j]>work[j]) incomplete = true; work[j]); //System.out.println(i + ":" + j + ":" + need[i][j] + ":" + if(need[i][j]!=0 && need[i][j]<=work[j]) work[j] = work[j] - need[i][j]; if(!incomplete) finish[i]=true; if(finish[i])

16 System.out.println("Process " + i + " can be completed"); else System.out.println("Process " + i + " can't be completed"); for(int i=0; i<n; i++) if(!finish[i]) return false; return true; void resourcerequest() int request[][] = 1,1,1,0, 2,2,0,0, 1,1,0,1, 1,1,0,0, 1,0,0,0; boolean safe=true; for(int i=0; i<n; i++) for(int j=0;j<m; j++) if(request[i][j]<=need[i][j]) if(request[i][j]<=avail[j]) avail[j] = avail[j] - request[i][j]; alloc[i][j] = alloc[i][j] + request[i][j];

17 need[i][j] = need[i][j] - request[i][j]; else System.out.println("Hey process " + i + "! resource " + j + " is not available now...try again later..."); else System.out.println("Process " + i + " has exceeded request for resource " + j + " hence is unsafe"); if(safe) else class deadlock_avoidance safe = false; System.out.println("the system is safe..."); System.out.println("the system is unsafe..."); public static void main(string args[]) throws Exception

18 Banker b = new Banker(); System.out.println("Applying safety algorithm..."); if(b.issafe()) System.out.println("The system is in safe state..."); else System.out.println("The system is not in safe state..."); System.out.println("Applying resource request algo..."); b.resourcerequest(); Output:

19 Practical No: 6 Aim: Demonstrate memory management using first/best/worst fit Source Code: memory_management.java import java.util.*; import java.io.*; class Job int instr[]; int process_id, size; Job(int pid, int n) process_id = pid; size = n; instr = new int[size]; for(int i=0;i<size;i++) int getsize() return size; int [] getinstr() return instr; int getprocessid() instr[i] = process_id + i+1;

20 return process_id; class MemMgmt int memory_array[]; Vector jobqueue; MemMgmt(Vector v) jobqueue = v; memory_array = new int[20]; for(int i=0;i<20;i++) memory_array[i] = 0; System.out.println("Initial memory layout..."); printarray(); void addjob(job newjob) jobqueue.add(newjob); void addsortedjob(job newjob) if(jobqueue.size()==0) jobqueue.add(newjob);

21 return; for(int i=0; i<jobqueue.size(); i++) Job j = (Job) jobqueue.elementat(i); if(j.getsize()>=newjob.getsize()) jobqueue.insertelementat(newjob,i); return; jobqueue.add(newjob); void printarray() System.out.println(); System.out.print(" "); for(int i=0;i<20;i++) System.out.print(memory_array[i]+" "); void firstfit() int mem_arr_index=0; for(int i=0; i<jobqueue.size(); i++) Job job = (Job) jobqueue.elementat(i);

22 int instr_array[] = job.getinstr(); if(20-mem_arr_index>=instr_array.length) System.out.print("\n\ncopying " + instr_array.length + " instructions at location " + mem_arr_index); is too big!"); void worstfit() for(int j=0;j<instr_array.length;j++) printarray(); else int mem_arr_index=0; memory_array[mem_arr_index] = instr_array[j]; mem_arr_index++; for(int i=jobqueue.size()-1; i>=0; i--) System.out.println("\nJob with process id " + job.getprocessid()+ " Job job = (Job) jobqueue.elementat(i); int instr_array[] = job.getinstr(); if(20-mem_arr_index>=instr_array.length)

23 System.out.print("\n\ncopying " + instr_array.length + " instructions at location " + mem_arr_index); big!"); else class memory_management for(int j=0;j<instr_array.length;j++) printarray(); memory_array[mem_arr_index] = instr_array[j]; mem_arr_index++; System.out.println("\nJob with process id " + job.getprocessid()+ " is too public static void main(string args[]) throws Exception Vector v = new Vector(); MemMgmt m = new MemMgmt(v); Job job1 = new Job(500, 9); Job job2 = new Job(200, 2); Job job3 = new Job(900, 6); System.out.println("\n\nEnter policy:\n1:first Fit\n2:Best Fit\n3:Worst Fit"); BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); int policy=integer.parseint(br.readline());

24 if(policy==1) System.out.println("\nApplying First Fit Policy..."); m.addjob(job1); m.addjob(job2); m.addjob(job3); m.firstfit(); else if(policy==2) System.out.println("\nApplying Best Fit Policy..."); m.addsortedjob(job1); m.addsortedjob(job2); m.addsortedjob(job3); //m.bestfit(); else if(policy==3) System.out.println("\nApplying Worst Fit Policy..."); m.addsortedjob(job1); m.addsortedjob(job2); m.addsortedjob(job3); m.worstfit(); Output:

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