Each process has four sections that is:

• Stack Segment
• Heap Segment
• Data Segment
• Code Segment

Similarly, even thread has these sections but text, Data and, Heap sections are common to all the threads but only the stack section is separate for each thread.

A multithreaded aware operating system also needs to keep track of threads. The items that the operating system must store that are unique to each thread are:

• Thread ID
• Stack Pointer, Saved Registers and Instruction Pointer(PC)
• Stack(Local variables, temporary variables, return address)
• Signal Mask
• Priority(Scheduling information)

The items that are shared among threads within a process are:

• Text segment (instructions)
• Data segment (static and global data)
• BSS segment (uninitialized data)
• Open file descriptors
• Signals
• Current working directory
• User and group IDs

Diag-1: Memory Layout with two Threads

Relevant Posts:

• Thread Introduction
• Types of Thread: User-Level and Kernel Threads
• Memory layout of a process
• Thread Control Block(TCB)
• Characteristics of a Thread
• Pros and cons of a Thread
• Process Vs Thread
• Thread Programming

Categories: Operating system (OS)