1. Computer fundamentals

1. Endianness

The order or sequence in which the bytes of a data is stored in a computer memory. It is expressed as big-endian (BE) or little-endian (LE).

  1. Big-endian: The most significant byte (MSB) is stored at the smallest memory address.
  2. Little-endian: The least significant byte (LSB) is stored at the smallest memory address.

2. Stack & Heap: Memory Allocation and management in python

When a variable is declared, for example x=10 and x=y both have the same value memory, i.e both variable points to the same object. Python optimizes memory utilisation by allocating the same object reference to a new variable if object already exists in memory with same value.

Memory address stored by a variable can be found using id().

The order of memory allocation in RAM is as follows (Low to high),

https://courses.engr.illinois.edu/cs225/sp2022/resources/stack-heap/
https://courses.engr.illinois.edu/cs225/sp2022/resources/stack-heap/

Heap is responsible to store all the values. A stack stores hold the references to the objects in the heap.

The name heap and stack does not have any relation to the data structure.

3. Processes and Threads

A process is a program that is currently under execution, whereas a thread is an execution entity that reside within a process that can be scheduled for execution. 1

A thread is an execution unit with its own stack and set of registers that reside in a process. A thread always belongs to exactly one process.

Threads are also known as light-weight processes.

Difference b/w single & multi-threaded process
Difference b/w single & multi-threaded process

In a multi-threaded process, each thread has its own stack and registers but shares the same memory. This lets access to code segments, files and data be shared among threads.

4. Mutexes and Semaphores

5.Global Interpreter Lock (GIL)

References


  1. https://afteracademy.com/blog/what-is-a-thread-in-os-and-what-are-the-differences-between-a-process-and-a-thread ↩︎

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