MULTI THREADINGTHE AIM OF MULTI THREADING IS TO PROVIDE CONCURRENT EXECUTION.[SIMULTANEOUS/PARELLELY PERFORMING MULTIPLE OPERATIONS]DEFNITION OF THREAD:-A FLOW OF CONTROL IS KNOWN AS THREAD.THE PURPOSE OF THREAD IS EXECUTING THE LOGIC OF JAVA PROGRAM WHICH IS RETURN IN THE FORM OF METHODS CONCURRENTLY.IF A JAVA PROGRAM CONTAINS MULTIPLE THREADS THEN IT IS CALLED MULTI THREADED PROGRAM.THE LANGUAGE LIKE C,C++.....E.T.C ARE TREATED AS SINGLE THREADED MODELLING LANGUAGES BECAUSE THEY EXECUTION ENVIRONMENT CONTAINS SINGLE FLOW OF CONTROL,PROVIDES SEQUENTIALEXECUTION,TAKES MORE EXECUTION TIME AND DOES NOT CONTAIN ANY LIBRARY FOR DEVELOPMENT OF MULTI THREADED APPS.THE LANGUAGE LIKE JAVA,.NET ARE TREATED AS MULTI THREADED MODELLING LANGUAGES BECAUSE THEIR EXECUTION ENVIRONMENT CONTAINS MULTIPLE FLOW OF CONTROLS,PROVIDES CONCURRENT EXECUTION,TAKES LESS TIME TO EXECUTE AND CONTAINS EFFECTIVE API'S FOR DEVELOPMENT OF THREAD BASED APPS.WHENEVER WE WRITE ANY JAVA PROGRAM THERE EXISTS TWO TYPES OF THREADS THEY ARE 1)FOREGROUND THREAD/CHILD THREAD2)BACK GROUND THREAD/PARENT THREADFORE GROUND THREAD ALWAYS EXECUTES LOGIC OF THE JAVA PROGRAM WHICH IS WRITTEN IN THE FORM OF METHODS CONCURRENTLY.A BACKGROUND THREAD ALWAYS MONITORS THE EXECUTION STATUS OF FOREGROUND THREADS.BY DEFAULT EVERY JAVA PROGRAM CONTAINS SINGL FOREGROUND THREAD AND SINGLE BACKGROUND THREAD,PROGRAMATICALLY ONE CAN CREATE MULTIPLE FOREGROUND THREADS AND RECOMMENDED TO CREATE ONE BACKGROUND THREADS.THE REALTIME IMPLEEMENTATIONS OF MULTI THREADING IS THAT TO DEVELOP REAL WORLD SERVER SOFTWARE LIKE TOMCAT,WEBLOGIC,WEBSPHERE....ETC.IN OTHERWORDS ALL THE SERVERS SOFTWRE'S DEVELOPED BY SERVER VENDORS IN JAVA LANGUAGE BY USING MULTI THEREADING CONCEPT.HENCE MULTI THREADING OF JAVA ISONE OF THE SPECIALIZED FORM OF MULTI TASKING OF O.S.HOW DO YOU JUSTIFY EACH AND EVERY JAVA PROGRAM IS MULTITHREADED?ANS:-WHEN EVER WE EXECUTE A JAVA PROGRAM THE LOGIC OF JAVA PROGRAM IS EXECUTED BY ONE OF THE THREAD KNOWN AS FOREGROUND THREAD.INTERNALLY TO MONITOR THE EXECUTION STATUS OF THE FOREGROUND THREAD ONE MORE THREAD IS CREATED KNOWN AS BACKGROUND THREAD.SO A JAVA PROGRAM CONTAINS TWO THREADS BY DEFAULT. HENCE,EVERY JAVA PROGRAM IS MULTI THREADED.WHAT ARE THE DIFFERENCES BETWEEN PROGRAM AND PROCESS?ANS:-PROGRAMPROCESS

*SET OF OPTIMIZED INSTRUCTIONS IS KNOWN AS PROGRAM.**PROGRAM WILL RESIDES IN THE SECONDARY MEMORY FOR ALONG TIME UNTIL WE DELETE.***PROGRAMATICALLY A PROGRAM CAN BE TREATED AS STATIC.*A PROGRAM UNDER EXECUTION IS KNOWN AS PROCESS.**PROCESSES RESIDES IN THE MAIN MEMORY FOR A LIMITED SPAN OF TIME UNTIL THE EXECUTION FINISHED.***PROGRAMATICALLY A PROCESS CAN BE TREATED AS DYNAMIC OBJECT.

DEFNITION OF CPU BURST TIME:-THE AMOUNT OF TIME TAKEN BY THE THREAD/PROCESS FROM CPU FOR ITS COMPLETE EXECUTION IS CALLED CPUBURST TIME.CPU BURST TIME IS DECIDED BY O.S WHEN THE PROGRAMIS ABOUT TO EXECUTE.IN REALWORLD WE WRITE TWO TYPES OF APPLICATIONS...PROCES BASED Vs THREAD BASED APPS (OR) NON MULTITASKING Vs MULTI TASKING APPS:-

PROCESS BASED APPS THREAD BASED APPS

*PROCESS BASED APPS(PBA)CONTAINS SINGLE FLOW OF CONTROL.**EG:-ALL THE SINGLE THREAD MODELLING LANG RELATED APPS ARE TREATED AS (PBA).***IN PBA CONTEXT SWITCHING IS MORE.****IN PBA EXECUTION TIME IS MORE.*****IN PBA FOR EACH&EVERY SUB-PROGRAM THERE EXISTS A SEPARATE ADDRESS SPACE.******ALL THE PBA RE TREATED AS HEAVY WEIGHT COMPONENTS.*******PBA PROVIDES ONLY SEQUENTIAL EXECUTION BUT NOT CONCURRENT.*THREAD BASED APPS(TBA) PROVIDES MULTIPLE FLOW OF CONTROLS.**EG:- ALL THE MULTI THREAD MODELLING LANG RELATED APPS ARE TREATED AS (TBA).***IN TBA CONTEXT SWITCHING IS LESS.****IN TBA EXECUTION TIME IS LESS.*****IN TBA,IRRESPECTIVE OF NO OF SUB-PROGRAM THERE EXISTS ONLY ONE ADDRESS SPACE.******ALL THE TBA RE TREATED AS LIGHT WEIGHT COMPONENTS.*******TBA PROVIDES BOTH CONCURRENT EXECUTION AND SEQUENTIAL EXECUTION.

DEFNITION OF ADDRESS SPACE:-IT IS AN AMOUNT OF TEMPORARY MEMORY SPACE CREATED BY O.S ON STACK MEMORY FOR THE TEMPORARY EXECUTION OF METHOD.DEFNITION OF CONTEXT SWITCHING:-IT IS THE MECHANISM OF SWITCH THE CPU FROM ONE ADRESS SPACE TO ANOTHER SPACE. *A HEAVY WEIGHT COMPONENT ALWAYS TAKES MORE EXECUTION TIME .AND LIGHT WEIGHT COMPONENT TAKES LESS EXECUTION TIME.NOTE:*FOR THE BEST APPS DEVELOPMENT CONTEXT SWITCHING MUST BE LESS.**EACH & EVERY TBA IS ONE OF THE PBA IN WHICH THERE EXISTS ONE MAIN PROCESS AND IT INTURNS CREATES NO OF SUB PROCESS.IN JAVA PROGRAMMING MAIN PROCESS IS CALLED "THREAD GROUP NAME"AND SUB PROCESS ARE CALLED "FOREGROUND THREADS" MEANT FOR EXECUTING THE METHOD CONCURRENTLY.

*WHERE AS A PBA WILL BE TREATED AS PBA IN EXECUTION BUT NOT TREATED AS TBA BECAUSE AT THE TIME OF EXECUTING PBA IT CONTAINS ONLY ONE FLOW OF CONTROL.[AND IT IS CALLED GREEN THREAD.}STATES/LIFE CYCLE OF A THREAD:THE NO OF STAGES/BREAKING POINTS OCCURING IN THE EXECUTION OF LOGIC OF THE JAVA PROGRAM WHICH IS WRITTEN IN THE FORM OF USER DEFINED METHODS BY THE THREAD ARE CALLED STATES OF THE THREAD.*STATES OF A THREAD ARE CLASSIFIED INTO 5 STEPS THEY ARENEW STATEREADY STATERUNNING STATEWAITING STATEHALTED/DEAD STATE.

-NEW STATE:-IN THIS STATE THREAS IS CREATED AND IT IS ABOUT TO ENTER INTO MAIN MEMORY.READY STATE:-IN THIS STATE THE THREAD IS ENTERES INTO MAIN MEMORY ,MEMORY SOACE IS ALLOCATED FOR THE THREAD AND FIRST TIME WAITING FOR THE CPU FOR EXECUTING THE LOGIC OF JAVA PROGRAM.RUNNING STATE:-IN THIS STATE THE THREAD IS UNDER THE CONTROL OF CPU,IN OTHERWORDS AS LONG AS THREAD IS EXECUTING LOGIC OF THE JAVA PROGRAM THEN THE STATE OF THREAD IS IN RUNNING STATE.HALTED STATE:-IN THIS STATE THE THREAD COMPLETES THE TOTAL EXECUTION ,IN OTHERWORDS WHEN THE THREAD COMPLETE ITS TOTAL CPU BURST TIME THEN THE STATE OF THE THREAD IS HALTEDWAITING STATE:-A THREAD IS SAID TO BE IN WAITING STATE IFF IT SATISFIES ANY OF THE FOLLOWING FACTORS 1)THREAD COMES TO WAITING STATE FOR REMAINING BURST TIME.2)SUSPENDING THE CURRENT EXECUTING THREAD.3)MAKING THE CURRENTLY RUNNING THREAD TO SLEEP FOR PERIOD OF TIME IN TERMS OF MILLI SECONDS.4)MAKING THE CURRENTLY EXECUTING THREAD TO WAIT WITH TIME.5)MAKING THE CURRENTLY EXECUTING THREAD TO WAIT WITHOUT TIME.6)JOINING THE THREADS.Q)WHAT DO YOU JUSTIFY THREAD OF JAVA EXECUTES CONCURRENTLY?ANS:-IF WE ASSUME THREADS ARE EXECUTING WITH THE DIFFERENCE OF HRS,MIN,SEC THEN SUCH THREAD EXECUTION IS CONSIDERED TO BE SEQUENTIAL EXECUTION[SLOWEST]AND NOT FOLLOWED IN JAVA PROGRAMMING.IF THREADS OF JAVA EXECUTING WITH THE DIFFERENCE OF MS OF TIME THEN SUCH EXECUTIONS IS CONSIDERED TO BE CONCURRENT EXECUTION[FASTEST] BECAUSE JAVA PROGRAMMER IS UNABLE TO DIFFERENTIATE THE DIFFERENCE OF MS OF TIME AND IT IS FOLLOWED IN THE JAVA PROGRAMMING HENCE DURING THE EXECUTION OF MULTI THREADING APPS ALL THE THREADS ARE EXECUTING WITH THE DIFFERENCE OF MS OF TIME BY FOLLOWING ROUND ROBIN ALGORITH CONCURRENTLY.NOTE:NEW STATE& HALTED STATE ARE CALLED OUT OF MEMORY STATES AND WHOSE EXECUTION STATUS IS FALSE.READY,RUNNING7WAITING STATES ARE CALLED IN MEMORY STATES AND WHOSE EXECUTION STATUS IS TRUE.DEFNITION OF PCB/JCB:-[PROCESS CONTROL BLOCK] IS ONE OF THE BUFFER[TEMPORARY MEMORY SPACE] CREATED BY O.S FOR EACH & EVERY THREAD WHEN IT IS ENTERED INTO READY STATFIRST TIME AND WHOSE PURPOSE IS TO CONTAIN TEMPORARY EXECUTION DETAILS OF THE THREAD.CREATING A THREAD IN JAVA:-IN JAVA PROGRAMMING WE CAN CREATE THREADS [FLOW OF CONTROL]BY USING 2 APPROACHES-----JAVA.LANG.THREAD--------------------------------------------------BY USING JAVA.LANG.RUNNABLE INTERFACEBY USING JAVA.LANG.THREAD:-BY USING JAVA.LANG.THREAD CLASS WE CAN CREATE ITS OBJECT(FLOW OF CONTROL)IN 3 WAYS THEY ARE --------BY USING NEW OPERATORThread t1=new Thread();----BY USING FACTORY METHODThread t2=Thread.CurrentThread();AN OBJECT OF SUB CLASS OF JAVA.LANG.THREAD IS ALSO AN OBJECT OF JAVA.LANG.THREAD.class Th1 extends Thread{-------------------------}Th1 t1=new Th1();HERE T1 IS AN OBJECT OF Th1 .Th1 IS THE SUBCLASS OF JAVA.LANG.THREAD.INDIRECTLY T1 IS AN OBJECT OF JAVA.LANG.OBJECT.PROFILE OF JAVA.LANG.THREAD-DATA MEMBERS:-Public Static Final Int MAX-PRIORITY(=10)Public Static Final Int NORM_PRIORITY(=5)Public Static Final Int MIN_PRIORITY(=1)THE DATA MEMBERS ARE CALLED THREAD PRIORITY MODIFIERS. THE PURPOSE OF THREAD PRIORITY MAODIFIERS IS THAT WHICH THREDS TO EXECUTE FIRST,SECOND AND LAST.THE DEFAULT PRIORITY OS THE THREAD IS NORM_PRIORITY(=5)CONSTRUCTORS:Thread();THIS CONSTRUCTOR IS USED FOR CREATING AN OBJECT OF THREAD CLASS WITHOUT GIVING USER FRIENDLY NAME TO THE THREAD.IF WE CREATE N-NUMBER OF OBJECTS WITH THIS CONSTRUCTOR THEN THEDEFAULT NAMES OF THE THREAD STARTS WITH THREAD-0,THREAD-1....GIVING THESE DEFAULT NAMES ARE NOT RECOMMEND TO GIVE USER FRIENDLY NAMES TO THE THREADEG:- Thread t1=new Thread();HERE T1 IS CALLED OBJECT/REFERRENCE VARIABLE AND WHOSE DDEFAULT NAME IS "THREAD-0".Thread(String);Thread t!=new Thread("HARSHA");THIS CONSTRUCTOR IS USED FOR CREATING AN OBJECT OF THREAD CLASS BY TO GIVE USER FRIENDLY NAME TO THE THREAD.Thread(Runnable);Thread(Runnable,String);INSTANCE METHODS:-Public Final Void getName(String)Public Final String getName()THE ABOVE METHODS ARE USED FOR GETTING THE USER FRIENDLY NAME TO THE THREAD AND GETTING THE NAME OF THE THREAD.EG:-Thread t1=new Thread(0;String tname=t1.getName();sop(tname);//Thread -1t1.getName("harsha");tname=t1.getName();sop(tname);//harshaNOTE :-ANY METHOD STATS WITH GET***(---)THEN IT IT IS CALLED_______MODIFIER AND WHOSE PURPOSE IS CHANGING THE VALUE OF THE OBJECT.IF ANY METHOD STARTS WITHGET***()THEN IT IS KNOWN AS INSPECTOR AND WHOSE PURPOSE IS TO OBTAINING THE VALUES FROM OBJECT.NOTE:-FINAL METHODS CAN'T BE OVERRIDDENPublic Final Void getPriority(int);Public Final Void getPriority();THE ABOVE METHODS ARE USED FOR GETTING THE PRIORITY TO THREAD AND GETTING PRIORITY OF THE THREAD.EG:-Thread t1=new Thread("harsha");int pv=t1.getPriority(0);sop(pv);//s=>NORM_PRIORITYThread Priority(Thread MAX_PRIORITY)pv=t1.getPriority();sop(pv)//10=>MAX_PRIORITYPublic Final Boolean IsAlive():-THIS METHOD RETURNS TRUE WHEN PROVIDED THE THREAD IS IN READY,RUNNING AND WAITING STATES.IT RETURNS FALSE WHEN THE THREAD IS NEW AND HALTED STATESPublic Void Run():-IT IS ONE OF THE PREDEFINED NULL BODY METHOD PRESENT IN THREAD CLASS.THIS METHOD IS ALWAYS FOR THE LOGIC OF THE JAVA PROGRAM WHICH IS TO BE EXECUTED BY JVM.Public Final Start():-*WHEN WE CALL THIS METHOD UPON THE THREAD CLASS OBJECT,IT CAN PERFORM 3 OPERATIONS--IT MOVES THE THREAD FROM NEW STATE TO READY STATE.---IT PROVIDES INTERNAL SERVICE OF MULTI THREADING(CONCURRENTLY,SYNCHRONISATION,INTERTHREAD COMMUNICATION) INTO THE THREAD CLASS OBJECT.----IT AUTOMATICALLY CALLS OWN()WHICH IS CONTAINING THE LOGIC OF THREAD----HENCE TO DEVELOP ANY TBA,CHOOSE AN APPROPRIATE USER DEFINED CLASS IT MUST EXTENDS JAVA.LANG.THREAD CLASS AND WE MUST OVERWRITE NULL BODY RUN() OF THREAD CLASSclass Th1 extends Thread{Public Void Run()//overridden method{----________}Th1 t1=new Th1();boolean b1=t1.IsAlive(0;sop(t1)''falseb1=t1.IsAlive();sop(b1);//true*IT IS NOT RECOMMENDE TO THE JAVA PROGRAMMER TO CALL RUN() DIRECTLY BECAUSE WE CANT GET THE MULTITHREADING SEVICES HENCE RUN()MUST BE CALLED ALWAYS TO THROUGH START()*Public Final Void Suspend():-THIS METHOD USED FOR SUSPENDING THE CURRENTLY EXECUTING THREADS WHEN WE CALL SUSPEND()UPON THE THREAD CLASS OBJECT, WHOSE EXECUTION WIL BE TERMINATED,PLACE THE CURRENT EXECUTION DETAILS IN THE PCB AND THREAD WILL BE ENTERED INTO WAITING STATET1.Suspend();*Public Final Void Resume();-THIS METHOS IS USED TO TRANSFERING THE SUSPENDED THREADS FROM WITING STATE TO READY STATE WHEN THE THREADS ARE RESUMED(RESTARTED)THEN THEY CONTINOUSTHEIR EXECUTION WHERE THEY LEFT OFF BEFORE THEIR SUSPENSION.T1.Resume();*Public Final Void Stop():THIS METHOD IS USED FOR TERMINATING /STOPS THE EXECUTION OF THE THREAD. WHEN WE RESTART THE STOPPER THREADS THEY START CONTAINING THEIR EXECUTION FROM THE BEGGININGPublic Final Void Join();THROWS JAVA.LANG.INTERRUPTED EXCEPTION THEIR COMPI=LETION OF EXECUTION AS A SINGLE AND HAND OVER TO THE GARBAGE COLLECTORTHIS PROCESS WILL IMPROVE THE EFFICIENCY OF MULTI THREADDING APPS*THE DEFAULT ENVIRONMENT OF MULTI THREADING SAYS INDIVIDUALLY COLLECTING THE THREADS AND INDIVIDUALLYHAND OVERING TO THE GARBAGE COLLECTOR WHICH IS ONE OF THE TIME CONSUMING PROCESS.Join()THROWS A PRE-DEFINED EXCEPTION CALLED JAVA.LANG.INTERRUPTTEDEXCEPTION--IT IS ONE OF THE UNCHECKED EXCEPTIONWHEN INTERRUPTED EXCEPTION OCCUR:-LET US ASSUME 'N'NO OF THREADS ARE CREATED STARTED ALL OF THEM UNDER EXECUTION,(N-1)THREADS ARE COMPLETED THEIR EXECUTION AND JOINED AND STILL,Nth THREAD IS UNDER EXECUTION.DUE TO MAIN MEMORY MANAGMENT OF O.S THREAD GROUPNAME IS ATTEMPTING TO COLLECT ALL THE THREADS EVEN THOUGH Nth THREAD IS UNDER EXECUTION,AT THIS TIME OF THREAD WITH RESPECT TO Nth THREAD JVM GENERATES A PRE DEFINED EXCEPTION CALLED JAVA.LANG.INTERRUPTEDEXCEPTION.EG:-try{t1.join();t2.join();:tn.join();}catch(InterruptedException ie){sop("problem in tread line");}STATIC METHODS:-static methods of thread class must be access with class namePublic Static Final Thread CurrentThread():it isone of the factory method and it is used for finding name of the threads which are default by meaning in java execution environmenteg:-Thread t=Thread.CurrentThread();sop(t);//Thread[Main,5,Main]----->[fgt,priority,tgn)t1.getName("harsha");sop(t);//[harsha,5,Main]Public Static Final Void Sleep(lang)throws java.lang.InterruptedExceptionthis method is used for making the currently executing thread to sleep for aperiod of time interms of MS.once the sleep time of the thread is over it will be automatically transferred into ready&running states .once the thread is sleeping further operations will not be performed until the sleep time is over.WHEN INTERRUPTEDEXCEPTION OCCURS:it is one of the un checked exception,let us assume first thread of the current program sleeping in one of the location of main memorymanagement of O.S,the second thread of same program attempting to sleep in the same location when the first thread is sleeping,wrto that thread .jvm generates a re defined exception called java.lang.InterruptedExceptioneg:try{=======thread.sleep(1000)=======}catch(InterruptedException ie){sop('problem in thread exception");}write a jp which will print preliminary info abt thread such as name of the threads which are default running,whose execution status,name of the defined programmersthread whose execution status head priority modifier value?ans://thdemo1.javaclass Thdemo1{Public Static Void main(String k[]){thread t1=thread.Current Thread();sop("default name="+t1)//thread(main,5,main)boolean state=t1.isAlive();sop("execution status of t1="+state);//treeThread t2=new Thread();//new threadsop("default name of priority defnition FGT=t2.getName(0);state =t2.isAlive();sop("exe status of t2="+state);//falsesop("val of max priority="+Thread.MAX_PRIORITY);//0sop('value of norm priority="+Thread.NORM_PRIORITY);sop{val of min="+Th)}}wajp which will print 1-10 numbers each and every sec.//thdemo2.javaclass th1 extends Thread{public void run(0{try{for(i=1;i