 | | | about process | about process 2005-08-12 - By Eris
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On Friday 12 August 2005 12:08 am, peeyush kr wrote:
> Hi friends,
>
> I want to know about the process that run in the background.
> there are three processes 1.active 2.sleep 3. zombi
When a process is active then it is actually executing on the CPU. An active
process has it's program code loaded into RAM.
When a process is sleeping, then it is not executing. Instead it is waiting
for something to happen. It may be waiting for the disk controller to read
data off of the hard disk, or it may be waiting for data to arrive on the
ethernet port. A process can sleep for many different reasons. A process
that is sleeping may have it's code and data moved out of RAM and onto the
swap partition if it has been waiting long enough.
A zombie process is one that has already terminated and been unloaded from
RAM, so it isn't using your memory. But it is still listed in the process
list because no one has checked its return value yet. (The return value is
stored in the process table entry, so that entry has to be kept around until
the return value is checked, even if the process itself is already unloaded
from RAM.)
Normally a zombie process will disappear very quickly because the init process
itself will remove it if no other program checks the return value. If the
zombie stays around, then it is usually because its parent process is still
running, but is not checking the return value. In that case you have to kill
the parent in order to kill the zombie.
Eris Caffee
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