Java Threads

1. Java Threads

2. What is Thread • Threading is a facility to allow multiple activities to coexist within a single process. • Specialized form of Multitasking. • Java is the first mainstream programming language to explicitly include threading within the language itself, rather than treating threading as a facility of the underlying operating system.

3. What is Thread • A process can support multiple threads, which appear to execute simultaneously and asynchronously to each other • Threads are independent, concurrent paths of execution through a program. • Each Thread has • Stack • Program Counter • Local Variables

4. Thread Sharing • Threads within a process are less insulated from each other than separate processes are. They share memory, file handles. • Does not depend upon Operating System.

5. Every Java program uses threads • Every Java program has at least one thread -- the main thread. When a Java program starts, the JVM creates the main thread and calls the program's main() method within that thread.

6. Why use threads • Make the UI more responsive • Take advantage of multiprocessor systems • Simplify modeling • Perform asynchronous or background processing.

7. Thread States

8. Thread Priority • JVM selects to run a Runnable thread with the highest priority. • All Java threads have a priority in the range 1-10. • Top priority is 10, lowest priority is 1. Normal priority by default is 5. • Thread.MIN_PRIORITY - minimum thread priority • Thread.MAX_PRIORITY - maximum thread priority • Thread.NORM_PRIORITY- maximum thread priority

9. Thread Scheduling • The JVM schedules using a preemptive , priority based scheduling algorithm. • All Java threads have a priority and the thread with he highest priority is scheduled to run by the JVM. • In case two threads have the same priority a FIFO ordering is followed.

10. Thread Methods

11. Thread Methods