Operating System: Inter Process Communication: Message Passing Shared Memory

saurabhschool

6 May 201408:04

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

🤝 Interprocess Communication (IPC) is the exchange of information between multiple processes, akin to people working together on a task.
🔍 Processes can be independent or cooperating; cooperating processes affect or are affected by each other, while independent processes do not communicate.
👥 Cooperation between processes can enhance information sharing, computation speed, modularity, and convenience in task division.
📬 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.
📝 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.
💌 Message passing involves one process sending a message to another, similar to friends making plans to meet, requiring a receiver to acknowledge the message.
🔄 The operating system facilitates IPC much like how humans interact, with processes communicating through shared resources or direct messaging.
🔄 The communication model involves processes sending and receiving messages, sometimes through an intermediary, which can be likened to a 'colonel' in the analogy.
📦 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.
🚫 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.
🔄 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

00:00

🤝 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.

05:01

🔄 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

💡Interprocess Communication

Interprocess Communication (IPC) refers to the mechanisms and methods allowing different processes to exchange information. In the video, IPC is likened to two people working together on a task, such as cooking, where one person cuts vegetables while the other cooks, requiring them to communicate and coordinate their actions. IPC is essential for processes to cooperate and share data.

💡Process

A process is an instance of a program in execution, with its own memory space and resources. The video script uses the analogy of a person performing a task to explain a process. For example, one person might be cutting vegetables, which represents a single process with its own specific job to do within a larger system.

💡Cooperating Processes

Cooperating processes are those that need to communicate and work together to accomplish a task. In the script, this is illustrated by two people making food together, where one's task depends on the other's actions. These processes affect and are affected by each other, necessitating IPC.

💡Independent Processes

Independent processes do not require communication with other processes to perform their tasks. The video uses the example of a person studying in a different room, who does not need to interact with the people cooking, thus not requiring IPC.

💡Shared Memory

Shared memory is a method of IPC where multiple processes have access to the same memory space, allowing them to exchange information directly. The script describes a notice board used by two friends working different shifts as an example of shared memory, where one leaves a message for the other to see later.

💡Message Passing

Message passing is another IPC method where processes communicate by sending and receiving messages. The video script uses the example of friends Bob and Sally making plans to meet, which represents the process of one process sending a message that another process must receive.

💡Synchronization

Synchronization in the context of IPC refers to the coordination of processes to manage access to shared resources or to ensure that messages are sent and received in the correct order. The script mentions blocking and non-blocking calls as forms of synchronization, where processes may wait for a message to be received or continue without waiting.

💡Blocking Send

A blocking send is a type of IPC operation where the sender process waits until the message is received by the intended recipient process. The video uses the analogy of knocking on someone's door and waiting for them to open it, emphasizing that the sender does not proceed until the message is acknowledged.

💡Blocking Receive

Blocking receive is when a process waits for a message to arrive before it can continue its execution. The script likens this to waiting for a Valentine's Day message, where the receiver waits for the message to arrive before reacting.

💡Non-Blocking Calls

Non-blocking calls, also known as asynchronous calls, allow a process to send a message without waiting for it to be received. The sender can continue with other tasks, and the message will be delivered independently. The script compares this to leaving a message in a mailbox without waiting for the recipient to retrieve it.

💡Producer-Consumer Problem

The producer-consumer problem is a classic synchronization issue in IPC where one process (the producer) generates data, and another process (the consumer) consumes it. The video script touches on this concept in the context of message passing, where one process sends messages that another process receives and processes.

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.