Thursday, July 16, 2009
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2:18 AM
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Process Creation
Parent process creates children processes, which, in turn create other processes, forming a tree of processes.
Resource sharing
* Parent and children share all resources.
* Children share subset of parent’s resources.
* Parent and child share no resources.
Execution
* Parent and children execute concurrently.
* Parent waits until children terminate.
Address space
* Child duplicate of parent.
* Child has a program loaded into it.
UNIX examples
* fork system call creates new process
* fork returns 0 to child , process id of child for parent
* exec system call used after a fork to replace the process’ memory space with a new program
Process Termination
Process executes last statement and asks the operating system to delete it (exit).
*Output data from child to parent (via wait).
*Process’ resources are deallocated by operating system.
Parent may terminate execution of children processes (abort).
*Child has exceeded allocated resources.
*Task assigned to child is no longer required.
*Parent is exiting.
:Operating system does not allow child to continue if its parent terminates.
:Cascading termination.
*In Unix, if parent exits children are assigned init as parent
Parent process creates children processes, which, in turn create other processes, forming a tree of processes.
Resource sharing
* Parent and children share all resources.
* Children share subset of parent’s resources.
* Parent and child share no resources.
Execution
* Parent and children execute concurrently.
* Parent waits until children terminate.
Address space
* Child duplicate of parent.
* Child has a program loaded into it.
UNIX examples
* fork system call creates new process
* fork returns 0 to child , process id of child for parent
* exec system call used after a fork to replace the process’ memory space with a new program
Process Termination
Process executes last statement and asks the operating system to delete it (exit).
*Output data from child to parent (via wait).
*Process’ resources are deallocated by operating system.
Parent may terminate execution of children processes (abort).
*Child has exceeded allocated resources.
*Task assigned to child is no longer required.
*Parent is exiting.
:Operating system does not allow child to continue if its parent terminates.
:Cascading termination.
*In Unix, if parent exits children are assigned init as parent
Posted by
Roger
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