- Program v/s Process :
1. A process is a program in execution.
- For example, when we write a program in C or C++ and compile it, the compiler creates binary code.
- The original code and binary code are both programs in high level and low level languages respectively.
2. When we actually run the binary code, it becomes a process.
- A process is an ‘active’ entity, while a program, is considered a ‘passive’ entity.
- A single program can create many processes when run multiple times; for example, when we open a .exe or binary file multiple times, multiple instances begin (multiple processes are created).
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PROCESS
- A process is a program in execution
- A process (program while executing) will need certain resources—such as CPU time, memory, files, and I/O devices—to accomplish its task.
- These resources are typically allocated by OS to the process while it is executing.
- A process is the unit of work in most systems.
--The operating system is responsible for the following activities in connection with process management:
- Creating and deleting both user and system processes
- Scheduling processes and threads on the CPUs
- Suspending and resuming processes
- Providing mechanisms for process synchronization
- Providing mechanisms for process communication
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1. Text section—the executable code (instructions in binary format)
2. Data section—Global variables
3. Heap section—memory that is dynamically allocated during program run time
4. Stack section—temporary data storage when invoking functions (such as function parameters, return addresses, and local variables)
5. The sizes of the text and data sections are fixed, as their sizes do not change during program run time.
6. However, the stack and heap sections can shrink and grow dynamically during program execution.
7. The Stack area is used during function calls.
8. The heap area is used to dynamically allocate the memory.
9. Although the stack and heap sections grow toward one another, the operating system must ensure they do not overlap one another.