Operating System: Inter Process Communication: Message Passing Shared Memory
Summary
TLDRThis lecture explores interprocess communication, where processes, similar to tasks performed by individuals, interact to complete work. It discusses two types of processes: independent and cooperating. Cooperating processes can affect each other and communicate through shared memory or message passing. The lecture also covers synchronization methods, including blocking and non-blocking calls, using relatable analogies to explain how processes wait for or send messages. Overall, it provides a comprehensive understanding of how processes communicate and synchronize within an operating system.
Takeaways
- ๐ค Interprocess Communication (IPC) is the exchange of information between multiple processes, akin to people working together on a task.
- ๐ Processes can be independent or cooperating; cooperating processes affect or are affected by each other, while independent processes do not communicate.
- ๐ฅ Cooperation between processes can enhance information sharing, computation speed, modularity, and convenience in task division.
- ๐ฌ Two primary methods of IPC are shared memory and message passing, which allow processes to interact as if they are leaving notes or sending direct messages.
- ๐ Shared memory is a common area where processes can read from or write to, like a notice board used by two friends working different shifts.
- ๐ Message passing involves one process sending a message to another, similar to friends making plans to meet, requiring a receiver to acknowledge the message.
- ๐ The operating system facilitates IPC much like how humans interact, with processes communicating through shared resources or direct messaging.
- ๐ The communication model involves processes sending and receiving messages, sometimes through an intermediary, which can be likened to a 'colonel' in the analogy.
- ๐ฆ The producer-consumer problem is an example of IPC where one process produces data and another consumes it, often managed by a buffer with potential bounded or unbounded sizes.
- ๐ซ Synchronization in IPC includes blocking or synchronous calls where the sender waits for the receiver to accept the message, like knocking on a door until it's opened.
- ๐ Non-blocking or asynchronous calls allow the sender to leave a message without waiting, similar to putting a letter in a mailbox and returning to other tasks.
Q & A
What is interprocess communication?
-Interprocess communication (IPC) is a mechanism that allows different processes to exchange data or signals, enabling them to coordinate and synchronize their actions.
Why do processes need to communicate with each other?
-Processes need to communicate to share information, speed up computation by working in parallel, increase modularity by dividing tasks, and for convenience in combining different tasks performed by separate processes.
Can you provide an example of how two people working together in a kitchen illustrate interprocess communication?
-In the kitchen example, one person cuts vegetables while the other cooks them. They need to communicate to coordinate their tasks, such as waiting for the vegetables to be cut before cooking, which is similar to how processes need to communicate to synchronize their actions.
What are the two main methods of IPC mentioned in the script?
-The two main methods of IPC mentioned are shared memory and message passing.
How does shared memory IPC work?
-Shared memory IPC involves a common memory space that multiple processes can access to exchange data. It's like a notice board where one person leaves a message for another to read and act upon.
Can you explain the concept of message passing IPC?
-Message passing IPC involves sending messages between processes. One process sends a message, and another receives it. It's similar to two friends making plans to meet by sending messages to each other.
What is the difference between blocking and non-blocking send in IPC?
-A blocking send means the sender process will wait until the message is received by the recipient before it can continue execution. Non-blocking send allows the sender to leave the message and continue its work without waiting for the message to be received.
What is the producer-consumer problem in the context of IPC?
-The producer-consumer problem is a classic synchronization issue where one process (the producer) generates data, and another process (the consumer) consumes it. The problem is to coordinate the production and consumption so that the producer does not overflow the buffer and the consumer does not read from an empty buffer.
What is a bounded buffer in IPC?
-A bounded buffer is a fixed-size buffer used in IPC. It assumes a limited capacity for storing data, unlike an unbounded buffer which theoretically has no limit to how much data it can hold.
Why is synchronization important in IPC?
-Synchronization is important in IPC to ensure that processes coordinate their actions properly. It prevents issues such as race conditions and ensures that data is accessed in a controlled manner to avoid conflicts.
How does the operating system facilitate IPC between processes?
-The operating system provides mechanisms and resources for processes to communicate, such as shared memory spaces and message queues. It also manages synchronization to ensure orderly communication between processes.
Outlines
๐ค Understanding Interprocess Communication
This paragraph introduces the concept of interprocess communication (IPC), explaining it as a method for processes to interact and share information. The analogy of two people cooking together is used to illustrate how processes can be dependent and cooperate, needing to communicate with each other. The paragraph also contrasts this with independent processes that do not require communication. It outlines the reasons for processes to cooperate, such as information sharing, computation speed up, modularity, and convenience. Two primary methods of IPC are discussed: shared memory, where processes access the same memory space, and message passing, where processes send messages to each other. The paragraph concludes with an analogy of a notice board for night and day shift workers to communicate, emphasizing the importance of IPC in coordinating tasks.
๐ Synchronization and Communication Models in IPC
The second paragraph delves into the producer-consumer problem as an example of cooperating processes in IPC, highlighting the use of buffers for message passing. It distinguishes between unbounded and bounded buffers, with the latter being more common due to fixed size limitations. The paragraph then discusses synchronization issues in IPC, such as blocking or synchronous calls, where the sender waits for the message to be received, compared to non-blocking or asynchronous calls, where the sender does not wait and the receiver may poll for messages. The summary also touches on the concepts of blocking send and receive, and non-blocking send and receive, providing relatable examples to clarify these technical terms. The paragraph concludes by emphasizing the importance of understanding IPC and synchronization for effective process communication.
Mindmap
Keywords
๐กInterprocess Communication
๐กProcess
๐กCooperating Processes
๐กIndependent Processes
๐กShared Memory
๐กMessage Passing
๐กSynchronization
๐กBlocking Send
๐กBlocking Receive
๐กNon-Blocking Calls
๐กProducer-Consumer Problem
Highlights
Interprocess communication (IPC) is the exchange of data or information between multiple processes.
Processes can be independent or cooperating, with cooperating processes affecting or being affected by each other.
Cooperating processes require IPC for tasks like information sharing, computation speedup, and modularity.
IPC can be achieved through shared memory, where processes access a common memory space, or message passing.
In shared memory IPC, processes communicate by reading from and writing to a shared memory segment.
Message passing involves sending and receiving messages between processes, like sending a note to a friend.
The operating system plays a role in facilitating IPC, similar to how humans interact in real life.
IPC models include message passing with a mailman (kernel) delivering messages, and shared memory where processes access a common memory space.
The producer-consumer problem is an example of cooperating processes, where one sends data and the other receives it.
Buffers can be unbounded, allowing unlimited data writing, or bounded, with a fixed size which is more common.
Synchronization is important in IPC to coordinate the execution of processes, avoiding issues like race conditions.
Blocking or synchronous calls involve processes waiting for IPC operations to complete before proceeding.
Non-blocking or asynchronous calls allow processes to continue executing without waiting for IPC operations.
Blocking send means the sender process waits until the message is received before continuing.
Blocking receive means the receiver process waits for a message to arrive before proceeding.
Non-blocking send allows the sender to leave a message and return without waiting for the receiver.
Non-blocking receive involves the receiver periodically checking for messages, without halting other tasks.
Understanding IPC is crucial for designing systems where multiple processes need to interact and share data efficiently.
Transcripts
in this lecture we are going to learn
about what is known as interprocess
communication so what is interprocess
communication so first to understand
this let's try to dissect this
interprocess so
process communicating with each other
okay so processes are basically some
tasks that are being performed and they
want to communicate so what will happen
with that so it's basically something
like two people are working on something
okay so let's say I'm working with my
friend and I'm making
some dish okay so two people are there
okay so both of them are working and
he's cutting basically some vegetable
and I'm cooking it on a frying pan okay
so both of us are basically interacting
with each other and I will be waiting
for him to supply me with the cut
vegetable and then I will cook and so on
so these are basically some interrelated
task okay so but some person if you one
friend is studying here so mostly he
will have no interaction because his
work is different so the processes might
be independent or they might be
cooperating person in the kitchen and
person in the study room they might not
be communicating they are independent
processes but if two people are
simultaneously making food and
cooperating with each other then they
are dependent so cooperating process can
affect or be affected by other processes
okay if he is busy and he has not cut
all the vegetables he will be waiting
for him okay and then let's say his next
task is to provide some oil to him so
again he will have they have some kind
of
communication but he is just studying
and he doesn't need them right now okay
reasons for cooperating process of
course so one is information Shar ing so
if he needs let's say salt okay so he
will ask this person that okay he will
somehow needs to communicate that please
bring me some salt and pepper okay so
they have to communicate computation
speed up let's say both of them now they
have a stove two stoves so they both
will be making two dishes and it will
become faster modularity also he will be
handling all the work of
cleaning
let's say and then something like
cutting vegetables and he will be frying
them he will be on the store convenience
okay so it is convenient people are
doing different works and then they are
combining so cooperating processes need
interprocess communication so similarly
if you are doing some process so two
processes they are trying to do some
work okay they need to communicate and
how do they communicate they use shared
memory and and then they use message
passing so they are the two different
ways of so let's try to see shared
memory so we two are friends okay and in
fact so they have a notice board so one
is working in a BP a call center and he
okay so he what he does he works at
night and the other one works in the day
shift okay two people are there so they
are they need to communicate okay so how
do they communicate they have a notice
board there and he says that okay okay
please cook for me okay something like
that so that other person when he goes
in the morning and then the other person
wakes up he will know that okay what he
needs to do so this is a shared memory
kind of process where two processes they
have a shared memory and that's how they
interact message
passing two people so let's say Bob and
Sally okay so they are friends and they
say that okay they can send a message
saying that okay let's meet at 4:00 okay
we will have some fun time so Bob and
Sally so they can interact so this is
message passing I can send some message
and Sally has to receive that message so
this is how they interact so this is
another way of communicating so this is
how the processes interact and operating
system is very much similar to how
humans interact okay so how everything
is related to person
so this happens then communication model
so process a process B so that's how
they're showing so in terms of processes
so they have a message passing so the
processing M sends a message to the
colonel and from there it goes to
process B okay so Colonel is the person
here who has the messages can
communicate through him so that's there
otherwise they have a shared memory here
and process a can write something into
the shared memory memory process we can
read that thing so This Is How They
communicate and then you have producer
consumer problem so cooperating process
someone is sending message and the other
one is receiving message so your buffer
where you write something that can be
unbounded buffer there is practically no
limit how much you can write but bounded
buffer assumes that there is a fixed
buffer size and which is the normal case
so let let's try to
see some more thing
okay and that
is basically synchronization okay so how
you synchronize so there is a blocking
or synchronous call where what happens
if you send if let's say I'm sending
something so that sender will block
until that message is received so it's
some kind of I'm going to some person's
house and I will be knocking okay so I
will be knocking at his door till that
person opens I cannot just leave that
message outside or in some mailbox I
will wait okay some there is very some
costly thing and I will wait till that
person or someone opens the door and I
give him I give him that costly gift or
something okay that is blocking send
another thing is blocking receive okay
so that happens I'm waiting for on
Valentine's Day some girl is waiting
that his boyfriend should send some
message okay so he is wait she's waiting
and waiting waiting till he gets the
message and then a smile comes on her
face so this is blocking receive so
something similar in the processes also
so process is waiting for some message
so like on a server so it always keep on
waiting for some request web request to
come so it's blocking
receive blocking send what example you
can think of so you can tell me in terms
of computers so non-blocking calls or
asynchronous calls or what a sender
sends a message he doesn't care if
someone is there or not he will put it
in the door at the door and then he'll
come back or in the mailbox so that is
it work and that somehow is in fact good
also that he doesn't have to wait but
what kind of thing you want that you
have to design based on your problem
non-blocking receive
I will keep on polling I'm not that much
concerned okay so I will keep sometimes
I check the door and see if some message
is there if there is I take it otherwise
I again go and do my work so that is
nonblocking receive so I hope you
understand this interprocess
communication till now what I said so
synchronization issue and how they
communicate so using message passing and
sending me uh sharing
memory a shared memory through that the
exchange I hope you understand this
thanks a lot
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