Java Multithreading Tutorial

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Multitasking:

Multitasking is a way of executing multiple tasks during the same period of time. Multiple tasks use common resources like CPU and main memory.

With a single CPU only one task can be running at one point in time, so the CPU uses context switching to perform multitasking. Context switch (Context means state) is the process of storing and restoring the state of a process so that execution can be resumed from the same point at a later time.

Types of Multitasking:

1. Multiprocessing.
2. Multithreading.

Multiprocessing:

Multiprocessing is a type of multitasking based upon processes i.e. context switching is done in-between processes. For example: Typing in notepad, Listening to music, and downloading files from the internet at the same time. Here in the example, we can clearly see that all applications are independent. Multiprocessing is the type of multitasking that is handled at the operating system level.

Process:

A process has a self-contained execution environment i.e. allocates a separate memory area. Context switch time is more in the case of processes because the switch is done between different memory areas.

Multithreading:

Multithreading is a type of multitasking based upon threads i.e. context switching is done in-between threads. In the case of multithreading, multiple independent tasks are executed simultaneously. These independent tasks are the part of same application. Multithreading is the type of multitasking that is handled at the program level.

Thread:

A thread is a lightweight process. Thread uses the process’s execution environment i.e. memory area. Context switch time is less in the case of threads because the switch is done within the same process’s memory area.

A thread represents a flow of execution. Every thread has a job associated with it.

Note: A thread can’t exist without a process, it exists within the process.

Difference between process and thread in Java:

                       Process                          Thread
  1. The process has its own main memory for execution.
  2. The process is considered a heavyweight component.
  3. One process can have multiple threads.
  4. Context switch time is more.
  1. Thread uses the process’s main memory for execution and shares it with other threads.
  2. Thread is considered a lightweight component.
  3. One thread can’t have multiple processes.
  4. Context switch time is less.

 

Java Multithreading tutorial:

Java concurrency tutorial