JVM, JRE, JDK and JIT ??




JIT:

 Just in time (JIT) is a part of Java Virtual Machine (JVM) architecture. The job of JIT inside JVM is to compile bytecode into machine executable code in real time, on a piece-by-piece, demand basis.






When Java programs are executed, JVM does not read the entire Bytecode and converts it 
into machine instructions. If JVM tries to do this approach then the program execution 
time will be delayed for hours. Java has overcome the latency of program execution 
time by interpreting the required bytecode and keep the rest of the code aside.
Just in time (JIT) helps to compile code that is only needed and at the same time boost 
the program performance. Wheather the Java programs are interpreted traditional 
way or on the fly the functionality and features like portability and security remains 
the same.


Summary:Java compiler converts the Java source code that you write into a binary 

program consisting of bytecodes. Bytecodes are machine instructions for the Java 
Virtual Machine. When you execute a Java program, a program called the Java 
interpreter (JIT) inspects and decipher the bytecodes into machine executable language.
JVM:
JVM (Java Virtual Machine) is an abstract machine. It is a specification that provides runtime
environment in which java bytecode can be executed.

 JVMs are available for many hardware and software platforms. JVM, JRE and JDK are platform
dependent because configuration of each OS differs. But, Java is platform independent.
The JVM performs following main tasks:

  1. Loads code
  2. Verifies code
  3. Executes code
  4. Provides runtime environment


JRE:
JRE is an acronym for Java Runtime Environment.It is used to provide runtime environment.It is
the implementation of JVM. It physically exists. It contains set of libraries + other files that JVM
uses at runtime.
Implementation of JVMs are also actively released by other companies besides Sun Micro Systems.





 JDK:
 JDK is an acronym for Java Development Kit.It physically exists.It contains JRE + development tools.




Comments

Post a Comment

Popular posts from this blog

Different Type of keys in Database Managemenet System.

Image
All super, candidate and primary, secondary keys are used to uniquely distinguish all rows in data base. But the main difference between them is. Super 🔑 -superset of candidate keys Candidate 🔑 -subset of super key, it is a single key or least combination of feild that uniquely  identifies every tuple. Primary 🔑- it is a candidate key that is most appropriate to become main key for the table. Secondary 🔑- candidate keys which are not selected as primary keys. Non-key attributes (attributes other than candidate keys) Non prime attributes (attributes other than primary key) Foreign 🔑?? It is a feild in one table that uniquely identifies a row in another table They are constraints between column of tables. Example:
Read more

FC Barcelona vs Real Madrid -El Clasico Rivalry.

Image
                              El Clasico The Story of the Rivalry between FC Barcelona and Real Madrid  The rivalry comes about as  Madrid  and  Barcelona  are the two largest cities in Spain, and they are sometimes  identified  with opposing political positions, with Real Madrid viewed as representing  Spanish nationalism  and Barcelona viewed as representing  Catalan nationalism . It is considered one of the biggest club  football  games in the world, and is among the most viewed annual sporting events.  It has always been a heated match, from both sides. Political background: The rivalry between the the two most successful clubs in football started with an oft-ignored political backstory and contrasts in how both clubs were made.  FC Barcelona was founded by --> Joan Gamper along with several foreign-...
Read more

Normalization in Database.

Image
What is normalisation in simple terms?? The process of organising data into columns and tables such as to reduce redundancy in the data is called normalisation. And to avoid insert, delete, and update anomalies. From ☝ answer many of you know about redundancy but not anomalies,  So what is a anomaly? Anomalies are problems that can occur in Poorly planned, un-normalised databases where all the data is stored in one table (a flat-file database). There are 3 types of anomalies  insert anomaly delete anomaly update anomaly I will explain the above with a simple example instead of explaining them with formal defnitions. Consider the below table. From the above table : Redundancy: When ever i add a student of cse department, the information about the department(i.e department name, hod and phone number) is repeating as you can see in above table. This redundancy should be reduced when you normalize the database. Insert anomaly: If i want to ...
Read more