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Questions and Answers
What is the purpose of the 'counter' variable in the code?
What is the purpose of the 'pthread_cancel(tmp_thread)' function call?
What is the significance of the 'pthread_join' function calls in the main function?
What is a thread in the context of CPU utilization?
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How are threads in a process different from a traditional process?
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What is the benefit of multi-threaded programming in the context of multi-core systems?
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What is the primary difference between concurrency and parallelism?
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What is parallelism in computing?
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What is data parallelism?
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What model allows for optimal utilization of resources and good performance?
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Which API is commonly used in UNIX OSs for thread creation and synchronization?
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What involves defining and launching a new thread using the pthread_create() function?
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What is the purpose of terminating a thread using pthread_exit() or pthread_cancel()?
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What type of threading is done by compilers and run-time libraries rather than programmers?
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What method involves creating a pool of threads that await work for efficient processing of tasks?
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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.