Processes Threads Handles

Processes

An instance of an executable
Think of it as a container
An application can have many processes i.e. your web browser
- each tab you open will spawn a new processes
A Process typically isnt aware of other processes on the machine
- It believes it is the only process on the machine
Each processes is started with a single thread, often called primary thread but can create additional threads from any of its threads

Three Types of Processes

Application Processes
- i.e chrome is an application process
- Can be terminated by the user
Background processes
- Get started automatically
- updating software
- anti viruses
Windows Processes
- system level processes
- automatically get launched at start up
  - device drivers
  - windows memory management

Process Priority

determines the amount of CPU time each processes will be allocated
there are 6 different levels
- Realtime
- High
- Above normal
- Normal
- Below normal
- Low

Low

only be given cpu time when there are no other higher priority processes running on the system

Normal

by default normal is used for the creation of a processes
- NORMAL_PRIORITY_CLASS

Realtime

full access to the cpu
very dangerous as this is higher than disk cache, mouse, keyboard
will leave no cycles for anything else

Threads

a thread is the entity within a processes that can be scheduled for execution
All threads of a process share its virtual address space and system resources
Process can have many threads
- also called multi threading

Differences Processes and Threads

processes use much more resources
threads are lightweight
processes are a team trying to complete a project
thread is a single member of the team working on a part of a project
processes are independent of each other
threads are dependent on each other

Handle

Generic unit of identification
pointer to our object
many different types of handles
- the most common one is handles to processes and handles to modules
handles are system wide