Process vs Thread

Process vs Thread.pdf

Process vs Thread


Process:

  • Definition:
    • A process is an independent and self-contained unit of execution in a computer system. It is an instance of a running program that includes its own memory space, resources, and system state.
  • Memory Space:
    • Each process has its own separate memory space. Processes do not share memory with other processes by default.
  • Resource Allocation:
    • Processes are allocated system resources, including CPU time, memory, file handles, and more. Each process operates independently of other processes.
  • Communication:
    • Inter-process communication (IPC) mechanisms, such as message passing or shared memory, are required for processes to communicate with each other.
  • Isolation:
    • Processes are isolated from each other, meaning that the failure of one process does not affect the execution of other processes.
  • Overhead:
    • Processes have a higher overhead compared to threads due to the isolation and resource allocation.
  • Creation and Termination:
    • Creating and terminating processes is generally more time-consuming than creating and terminating threads.
  • Process typically has a main thread. The main thread is the initial thread that is created when a program starts. It is the thread responsible for executing the main entry point of the program, such as the main function in C or C++.

Thread:

  • Definition:
    • A thread is the smallest unit of execution within a process. It shares the same resources and memory space as other threads within the same process.
  • Memory Space:
    • Threads within the same process share the same memory space. They can directly access the memory of other threads within the same process.
  • Resource Allocation:
    • Threads within a process share the same resources. They can efficiently communicate with each other through shared memory.
  • Communication:
    • Threads within the same process can communicate directly through shared variables and data structures. No special mechanisms are required for communication.
  • Isolation:
    • Threads within the same process are not fully isolated. The failure of one thread can potentially affect the entire process.
  • Overhead:
    • Threads have lower overhead compared to processes because they share resources and memory.
  • Creation and Termination:
    • Creating and terminating threads is generally faster than creating and terminating processes.

Summary:

  • A process is an independent program with its own memory space, resources, and system state.
  • A thread is the smallest unit of execution within a process, sharing the same resources and memory space with other threads in the same process.
  • Processes are isolated, and communication between them requires special mechanisms.
  • Threads within the same process can communicate directly through shared memory.
  • Processes have higher overhead due to their isolation and separate resource allocation.
  • Threads have lower overhead as they share resources within the same process.
  • Processes are more robust in the face of failures since one process's failure does not affect others.
  • Threads within a process are less isolated, and the failure of one thread can potentially affect the entire process.


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