Paralel Prosesler

1
Paralel Prosesler
Proses Rapor_Yaz Begin while (true)
do .......bir süre bekle... print(sayac) sayac
0 end end

• Proses Gözle
• Begin
• while (true) do
• ......olayi gözle......
• sayac
• end
• end

sayac ortak degisken
2
Problem
Proses Rapor_Yaz Begin while (true)
do .......bir süre bekle... print(sayac) sayac
0 end end

• Proses Gözle
• Begin
• while (true) do
• ......olayi gözle......
• sayac
• end
• end

Kritik Bölge Ilan Edilir

1.) Program sayac noktasinda kesildi ve
sayac degeri 8 idi. 3.) devam edip 3 olay
gözledi ve sayac degerini 3 yapti , durdu.
2) print(sayac) ile ekrana 8 yazdi ve sonra
kesildi. 4.) sayac0 atamasi yapti, sayac
içindeki 3 bilgisi kayboldu
3
Diger Problem

• sayac makine düzeyi anlaminda hangi
  islemlerinden olusur

ACC ? 5 kesildi INC 6? sayac
sayaci ekrana yaz sayac? 0
LDA sayac INC STA sayac
4
Semafor integer deger 0,1,2... kuyruk
isaretcisi prosesler bu kuyrukta askiya
alinirlar

• Kritik Bölgeye Giris ? P(mySemafor)
• ----- kritik bölge
• Çikista ? V(mySemafor)

V islemi If(kuyrukta bekleyen varmi) uyandir Els
e mySemafor
P islemi If(mySemaforgt0) mySemafor - - Else
kuyruk üzerinde bekle
5
Monitor Yapisi

• Kritik bölüm içindeki kodlar bu monitor içine
  yazilir
• Böylece Monitor içinde hem kaynak degiskenler hem
  de tüm kritik bölüm kodlari yer alir
• Monitörün kod parçalarina entry ismi verilir
• Monitorden bir anda sadece bir proses
  yararlanabilir.

Proses C
Proses A
Anahtar_al
Anahtar_ver
sayac
Proses B
Veri tabanini kullan
Proses D
mesgul
6
Mutual - Obstacle
7
Fatal Lock
8
JAVA Thread

• public interface Runnable
• abstract public void run()

class Animation implements Runnable ...
public void run( ) while ( true ) // draw
Frames ...
Animation happy new Animation("Mr.
Happy") Thread myThread new Thread( happy )
myThread.start( )
9
A natural-born thread

• class Animation extends Thread
• ...
• public void run( )
• while (true )
• // draw Frames ...

Animation bouncy new Animation("Bouncy")
bouncy.start( )
10
Using an adapter

• class Animation
• public void startAnimating( )
• // do setup, load images, etc.
• ...
• // start a drawing thread
• myThread new Thread ( new Runnable( )
  
• public void run() drawFrames( )
  
• )
• myThread.start( )
• private void drawFrames( )
• // do animation ...

11
Synchronization

• class SpreadSheet
• int cellA1, cellA2, cellA3
• synchronized int sumRow( )
• return cellA1 cellA2 cellA3
• synchronized void setRow( int a1, int a2, int
  a3 )
• cellA1 a1
• cellA2 a2
• cellA3 a3
• ...

synchronized ( myObject ) //
Functionality that needs to be synced
12
notifierMethod waiterMethod

• class MyThing
• synchronized void waiterMethod( )
• // do some stuff
• wait( ) // now wait for notifier to
  do something
• // continue where we left off
• synchronized void notifierMethod( )
• // do some stuff
• notify( ) // notify waiter that we've
  done it
• // do more things
• synchronized void relatedMethod( )
• // do some related stuff
• ...

13

• import java.util.Vector
• class Producer extends Thread
• static final int MAXQUEUE 5
• private Vector messages new Vector( )
• public void run( )
• try
• while ( true )
• putMessage( )
• sleep( 1000 )
• catch( InterruptedException e )
• private synchronized void putMessage( )
• throws InterruptedException
• while ( messages.size( )
  MAXQUEUE )
• wait( )
• messages.addElement( new
  java.util.Date().toString( ) )

// called by Consumer public synchronized
String getMessage( ) throws
InterruptedException notify( )
while ( messages.size( ) 0 ) wait(
) String message (String)messages.fir
stElement( ) messages.removeElement(
message ) return message
// end of class Producer
14

• public class Consumer extends Thread
• Producer producer
• Consumer(Producer p)
• producer p
• public void run( )
• try
• while ( true )
• String message
  producer.getMessage( )
• System.out.println("Got message
  " message)
• sleep( 2000 )
• catch( InterruptedException e )
• public static void main(String args)

15
Producer- Comsumer Output

• java Consumer
• The output is the timestamp messages created by
  the Producer
• Got message Sun Dec 19 033555 CST 1999
• Got message Sun Dec 19 033556 CST 1999
• Got message Sun Dec 19 033557 CST 1999
• ...

16
Thread Priority
17
class MyThread extends Thread String
message MyThread ( String message )
this.message message
public void run( ) while ( true )
System.out.println( message )

• public class Thready
• public static void main( String args )
  
• new MyThread("Foo").start( )
• new MyThread("Bar").start( )
• // end of class Thready

class Thready public static void main(
String args ) new
MyThread("Foo").start( ) Thread bar
new MyThread("Bar") bar.setPriority(
Thread.NORM_PRIORITY 1 ) bar.start(
)
18

• public class SimpleThread extends Thread
• public SimpleThread(String str)
• super(str)
• public void run()
• for (int i 0 i lt 10 i)
• System.out.println(i " "
  getName())
• try
• sleep((long)(Math.random()
  1000))
• catch (InterruptedException e)
• System.out.println("DONE! " getName())

19
0 Jamaica 0 Fiji 1 Fiji 1 Jamaica 2 Jamaica 2
Fiji 3 Fiji 3 Jamaica 4 Jamaica 4 Fiji 5
Jamaica 5 Fiji 6 Fiji 6 Jamaica 7 Jamaica 7
Fiji 8 Fiji 9 Fiji 8 Jamaica DONE! Fiji 9
Jamaica DONE! Jamaica

• public class TwoThreadsDemo
• public static void main (String args)
• new SimpleThread("Jamaica").start()
• new SimpleThread("Fiji").start()

20
Makarna Yiyen Filozoflar
5
1
1
5
2
4
4
3
2
3