Understanding Threads in Processes

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Questions and Answers

What is the purpose of the 'counter' variable in the code?

To terminate thread_func2 after a certain number of iterations

To monitor the overall progress of the main function

To track the number of times thread_func1 has run (correct)

To synchronize the execution of thread_func1 and thread_func2

What is the purpose of the 'pthread_cancel(tmp_thread)' function call?

To terminate thread1 and thread2 simultaneously

To signal the completion of thread_func1

To cancel the execution of thread2 after a specific condition is met (correct)

To pause the execution of both threads for a given time

What is the significance of the 'pthread_join' function calls in the main function?

To pause the execution of the main function until both threads are canceled

To create new threads for thread_func1 and thread_func2

To wait for thread1 and thread2 to finish their execution before exiting main (correct)

To synchronize the printing of 'thread number one' and 'thread number two'

What is a thread in the context of CPU utilization?

A basic unit of CPU utilization Signup and view all the answers

How are threads in a process different from a traditional process?

Threads share code section, data section, and other OS resources Signup and view all the answers

What is the benefit of multi-threaded programming in the context of multi-core systems?

Improves concurrency and more efficient use of multiple cores Signup and view all the answers

What is the primary difference between concurrency and parallelism?

Concurrency supports more than one task by allowing all tasks to make progress, while parallelism involves simultaneous execution of multiple tasks Signup and view all the answers

What is parallelism in computing?

Execution of more than one task simultaneously Signup and view all the answers

What is data parallelism?

Distributing subsets of the same data across multiple cores and performing the same operation on each Signup and view all the answers

What model allows for optimal utilization of resources and good performance?

Many-to-Many Signup and view all the answers

Which API is commonly used in UNIX OSs for thread creation and synchronization?

Pthreads Signup and view all the answers

What involves defining and launching a new thread using the pthread_create() function?

Creating a thread Signup and view all the answers

What is the purpose of terminating a thread using pthread_exit() or pthread_cancel()?

Terminating a thread Signup and view all the answers

What type of threading is done by compilers and run-time libraries rather than programmers?

Implicit threading Signup and view all the answers

What method involves creating a pool of threads that await work for efficient processing of tasks?

Thread pools Signup and view all the answers

Study Notes

Parallelism is a computing concept where more than one task is executed simultaneously.
Parallelism can be achieved on a multi-core system.
Types of parallelism include data parallelism and task parallelism.
Data parallelism distributes subsets of the same data across multiple cores and performs the same operation on each.
Task parallelism distributes threads across cores, each thread performing a unique operation.
Multi-threading is one way to achieve parallelism.
User threads are managed by user-level threads libraries, while kernel threads are supported by the kernel.
Multi-threading models include Many-to-One, One-to-One, and Many-to-Many.
In the Many-to-One model, many user-level threads are mapped to a single kernel thread. This can result in reduced concurrency and poor performance on multi-core systems.
In the One-to-One model, each user-level thread maps to a single kernel thread. This allows for more concurrency and better performance but comes with more overhead.
In the Many-to-Many model, many user-level threads are mapped to many kernel threads. This allows for optimal utilization of resources and good performance.
Thread libraries provide an API for creating and managing threads.
Pthreads is a POSIX API for thread creation and synchronization, and is commonly used in UNIX OSs.
Thread ID is the thread analogue to the process ID and is assigned by the Pthread library.
Creating a thread involves defining and launching a new thread using the pthread_create() function.
Terminating a thread involves either calling pthread_exit() from within the thread or using pthread_cancel() to terminate another thread.
Joining and detaching threads are used to manage the execution of threads. Joining allows one thread to wait for the termination of another, while detaching allows a thread to terminate immediately and automatically release its resources.
Implicit threading is a method of threading where the creation and management of threads is done by compilers and run-time libraries rather than programmers.
Methods of implicit threading include thread pools, fork-join, and OpenMP.
Thread pools create a pool of threads that await work, allowing for efficient processing of tasks.
Fork-join involves forking multiple threads and joining them together to process a task, allowing for parallelism in a tree-like structure.
OpenMP is a set of compiler directives and APIs for C, C++, and FORTRAN that identifies parallel regions of code.
Thread cancellation allows for a thread to be terminated before it has finished, allowing for better performance in some cases.
There are two general approaches to thread cancellation: asynchronous cancellation and deferred cancellation.
In asynchronous cancellation, the thread is terminated immediately.
In deferred cancellation, the thread is allowed to periodically check if it should be cancelled, allowing for a more graceful termination.

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Description

Learn about the concept of threads as a basic unit of CPU utilization within processes. Explore how multiple threads can perform various tasks simultaneously and share resources within a process, enhancing the efficiency of applications.