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SEARCH KEYWORD -- OS Threads

  Java Concurrency Basics: CountDownLatch and CyclicBarrier

CountDownLatch CountDownLatch can be used in synchronizing behavior among threads, it makes one or more threads wait for some actions in other threads to be completed. It has a property count which defines how many countDown() need to be called before other threads which called await() to be waked up.  When a thread calls CountDownLatch.await(), the thread will be blocked until the value of count becomes 0. The initial value of count can be specified when creating the CountDownLatch instanc...

   JAVA,JAVA CONCURRENCY,COUNTDOWNLATCH,CYCLICBARRIER     2018-03-25 07:02:40

  Exit main thread and keep other threads running in C

In C programming, if using return in main function, the whole process will terminate. To only let main thread gone, and keep other threads live, you can use thrd_exit in main function. Check following code: #include #include #include int print_thread(void *s) { thrd_detach(thrd_current()); for (size_t i = 0; i < 5; i++) { sleep(1); printf("i=%zu\n", i); } thrd_exit(0); } int main(void) { ...

   C LANGUAGE,MULITHREAD,MAIN THREAD     2020-08-14 21:20:04

  Simple explanation about process and thread

Process and thread are two basic concepts of operating system, but they are a bit abstract which cannot be  mastered easily. There is an analogy which explains these concepts very well. 1. The kernel of the computer is CPU, it handles all the computing tasks, it's like a factory and will run all the time. 2. Assume there is power limitation for the factory, it can only supply to one unit once,i.e, when one unit is working, other units must stop and wait. The meaning behind this is that eac...

   Process,Thread,CPU,Operating system     2013-04-24 11:33:10

  Multithreading interview questions in Java

Multithreading as a widespread programming and execution model allows multiple threads to exist within the context of a single process. These threads share the process' resources but are able to execute independently. The threaded programming model provides developers with a useful abstraction of concurrent execution. However, perhaps the most interesting application of the technology is when it is applied to a single process to enable parallel execution on a multiprocessor system.Many programme...

   Multithreading,Java,Interview     2012-05-28 06:33:25

  Concurrency vs Parallelism

Concurrency and parallelism are two related concepts which deal with executing tasks "simultaneously". From Sun's Multithreaded Programming Guide: Concurrency: A condition that exists when at least two threads are making progress. A more generalized form of parallelism that can include time-slicing as a form of virtual parallelism. Parallelism: A condition that arises when at least two threads are executing simultaneously. These two definitions are too formal to be understood easily. On t...

   Concurrency,Parallelism,Thread     2013-08-07 23:42:33

  Why is single threaded Redis so fast

Redis is a high-performance, in-memory key-value database. According to official test reports, it can support around 100,000 QPS (queries per second) on a single machine. However, Redis uses a single-threaded architecture in its design. Why does Redis still have such high performance with a single-threaded design? Wouldn't it be better to use multiple threads for concurrent request processing? In this article, let's explore why Redis has a single-threaded architecture and still maintains its spe...

   REDIS,SINGLE-THREADED,MULTI-THREADING     2023-02-28 05:16:22

  PHP Multithreading – Faking It

PHP doesn’t really support multi-threading per se but there are ways to do “fake” multithreading. Here’s one I saw in the PHPClasses.org newsletter – Multi-thread Simulation. Note that this class is intedend for use on a webserver, as opposed to running PHP scripts from a command line (or similar). Check the end of this post for some alternatives you can try if you’re using PHP as a stand-alone scripting language. Now, I’m going to be lazy and just ...

   PHP,Multithreading,Possible,CURL,Fake,Si     2011-09-04 23:07:22

   Python – parallelizing CPU-bound tasks with multiprocessing

In a previous post on Python threads, I briefly mentioned that threads are unsuitable for CPU-bound tasks, and multiprocessing should be used instead. Here I want to demonstrate this with benchmark numbers, also showing that creating multiple processes in Python is just as simple as creating multiple threads. First, let’s pick a simple computation to use for the benchmarking. I don’t want it to be completely artificial, so I’ll use a dumbed-down version of factorization...

   Python,Multitasking,Multiprocessing,CPU bound     2012-01-17 11:38:22

  Python threads: communication and stopping

A very common doubt developers new to Python have is how to use its threads correctly. Specifically, a large amount of questions on StackOverflow show that people struggle most with two aspects: How to stop / kill a threadHow to safely pass data to a thread and back I already have a blog post touching on these issues right here, but I feel it’s too task-specific for sockets, and a more basic and general post would be appropriate. I assume the reader has a basic familiarity with Pytho...

   Python,Multithreading,Communication,Synchronize     2011-12-28 07:38:32

  Practice of using spinlock instead of mutex

Spinlock and mutex are two important concepts in multithreading programs. They are used to lock some shared resource to prevent concurrent access which may affect data consistency. But they do have differences, what are the differences? when should we use spinlock instead of mutex? The Theory In theory, when a thread tries to lock a mutex and it does not succeed, because the mutex is already locked, it will go to sleep, immediately allowing another thread to run. It will continue to sleep until...

   Spinlock,Mutex,Concurrency     2014-04-19 21:54:12

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