Processes may be in one of 5 states:
New - The process is in the stage
of being created.
Ready - The process has all the resources available that it needs to
run, but the CPU is not currently working on this process's instructions.
Running - The CPU is working on this process's instructions.
Waiting - The process cannot run at the moment, because it is waiting
for some resource to become available or for some event to occur. For example
the process may be waiting for keyboard input, disk access request,
inter-process messages, a timer to go off, or a child process to finish.
Terminated - The process has completed.
Five state model Diagram :
Process Brief
Explanation:
A process is an instance of a program running in a computer. It is close in
meaning to task, a term used in some operating systems. In UNIX and some other
operating systems, a process is started when a program is initiated (either by
a user entering a shell command or by another program). Like a task, a process
is a running program with which a particular set of data is associated so that
the process can be kept track of. An application that is being shared by
multiple users will generally have one process at some stage of execution for
each user.
A process can
initiate a sub process, which is a called a child process (and the initiating process
is sometimes referred to as its parent). A child process is a replica of the
parent process and shares some of its resources, but cannot exist if the parent
is terminated.
Processes can
exchange information or synchronize their operation through several methods of
inter-process communication (IPC).
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