1. Understand Process Management
• Relationship Between Processes
1

2. Recap
In the last class, you have learnt
• Process Creation
• Process Termination
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3. Objectives
On completion of this class, you will be able to
know
• Relationship between Processes
• Reasons for providing an environment that allows
Process cooperation
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4. Relationship Between Processes
• Concurrent processes executing in the operating system may be
either “Independent processes” or “Cooperating processes”
• A process is independent if it cannot affect or be affected by the
other processes executing in the system
• A process that does not share any data with any other process is
independent Process
• A Process is a cooperating, if it can affect or be affected by the
other processes executing in the system
• Any process that shares data with other processes is a
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cooperating process

5. Relationship Between Processes
Reasons for Process cooperation
• Information sharing
• Computation speedup
• Modularity
• Convenience
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6. Relationship Between Processes
Information Sharing
• Several users may be interested in same piece of information,
Ex. Shared file
• Must provide an environment to allow concurrent access to
these types of resources
Computation Speedup
• To run a particular task faster, we must break it into subtasks
• Each of the subtask will execute in parallel with others
• This is possible only if computer has multiple processing
elements ( CPU or I/O channels)
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7. Relationship Between Processes
Modularity:
• For cooperating between systems we have to construct the
system in a modular fashion
• Dividing the system function into separate processes or
threads
Convenience:
• Even an individual user may work on many tasks at the same
time
• For instance, a user may be editing, printing and compiling in
parallel
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8. Cooperating Processors
• Concurrent execution that requires cooperation among the
processes requires mechanisms to allow processes
communicate with one another
• To illustrate the concept of cooperating processes look at the
– Example: Producers-consumers problem
• A producer process produces information that is consumed by
a consumer process
– Example :
• A print program produces character that are consumed
by the printer driver9CM402.14 8

9. Cooperating Processes
• To concurrently run producers and consumers processes we
must have a buffer of items that can be filled by the producer
and emptied by the consumer
• A producer can produces one item while the consumer is
consuming another item
• The producer and consumer must be synchronized, so that
– the consumer does not try to consume an item that has not yet been
produced
• The consumer must wait until an item is produced
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10. Example
• Solutions to producer-consumer problem may implement the
buffer interface shown follows
Interface for buffer implementation
Public interface Buffer
{
// producers call this method
public abstract void insert (object item);
// consumers call this method
public abstract object remove( );
}
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11. Example
• The producer process involves the insert( ) method when It
wishes to enter an item in the buffer
insert( ) method
Public void insert (object item){
While (count= = BUFFER SIZE)
; // do nothing - - no free buffers
+ + count;
buffer [in]=item;
in=(in+1) % BUFFER -SIZE;
}
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12. Example
• The consumer calls the remove( ) method when it wants to consume an item
from the buffer
remove method
Public object remove ( ) {
Object item;
While (count= = 0)
; // do nothing - - nothing to consume
// remove an item from the buffer
--count;
item=buffer [out];
out=(out+1) % BUFFER _ SIZE;
return item; } 9CM402.14 12

13. Summary
In this class, you have learnt
• Relationship between the processes
• Reasons for Process cooperation
• Cooperating Processes
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14. Frequently Asked Questions
1. Explain about cooperating process
2. What are the several reasons for cooperating processes
3. Explain about the relationship between processes
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15. Quiz
1. A process is ____________ if it cannot affect or be
affected by the other processes executing in the system
a) Independent
b) Dependent
c) Cooperating
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16. Quiz
2. A process is ________ if it can affect or be affected by
other processes executing in the system.
a) Cooperating
b) Independent
c) Dependent
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17. Quiz
3. A process that does not share any data with any
other process is
a)Independent Process
b) Cooperating
c) Dependent
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18. Other subject materials
• Web designing
• Micro processors
• C++ tutorials
• java
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