If we can get the computer to execute some of these subtasks at the same time, with no change in our program’s results, our overall task will continue to get as much processing as it needs, but it will complete in a shorter period of time. For instance, if our program is a marine navigation system, we could launch separate tasks to perform each sounding and maintain other tasks that calculate relative depth, correlate coordinates with depth measurements, and display charts on a screen. Today, it’s frequently useful to look at our program (our very big task) as a collection of subtasks.
One of those capabilities is a computing system’s ability to perform multitasking. If all of our programs run like this, we’re very likely not using our computer to its fullest capabilities.
How to exit pthread c serial#
When we package our work according to the traditional, serial notion of a program, we’re asking the computer to execute it close to the humble performance of a computer of yesterday. Today’s computers can do many things at once (or very effectively make us believe so). Since then, computers have become more and more powerful and grown more efficient at performing the work that makes running our programs possible. Not too many years ago, single instructions were how we delivered work to computers.
But we have one way into our program, regardless of its spins and hops, and one way out.
If programming instructions were squares on a game board, we can see that our program has places where we stall, squares that we cross again and again, and spots we don’t cross at all. Our notion of a program can include certain eccentricities, like loops and jumps, that make a program more resemble a game of Chutes and Ladders than a piano roll. When describing how computers work to someone new to PCs, it’s often easiest to haul out the old notion that a program is a very large collection of instructions that are performed from beginning to end. Pthread_named_by_parent.Specifying Potential Parallelism in a Concurrent Programming Environment Making sure the parent thread gave the pthread a name.įprintf(stdout, "I am thread with ID '%lu', my name is '%s' and my parent gave me my name\n", tid, thread_name ) Ĭonst int setname_rv = pthread_setname_np(thread_info.thread_id, "Bob Marley") Added an artificial delay for the sake of the example. #include is needed for the resolution of unsigned int sleep(unsigned int seconds) The next code, creates a pthread and the parent gives the thread a meaningful name. The pthread_join() function suspends execution of the calling thread until the target thread terminates, unless the target thread has already terminated.Ĭonst int join_rv = pthread_join(thread_info.thread_id, NULL) Įxample 2: The parent decides for the pthread name so we print pthread_t as an unsigned long intįprintf(stdout, "I am thread with ID '%lu', my name is '%s' and I gave me my name by myself\n", tid, thread_name ) Ĭonst int create_rv = pthread_create(&(thread_info.thread_id), NULL, &self_named_thread, (void *) &thread_info) Usually pthread_t is defined as follows: This function always succeeds, returning the calling thread's ID. Struct thread_info_t *thread_info = (struct thread_info_t *) data Ĭonst int setname_rv = pthread_setname_np(thread_info->thread_id, "Tom Hanks") Ĭhar thread_name Ĭonst int getname_rv = pthread_getname_np(thread_info->thread_id, thread_name, MAX_LENGTH_PTHREAD_NAME) We know that the input data pointer is pointing to a thread_info_t so we are casting it to the right type. This is the thread that will be called by pthread_create() and it will be executed by the new thread. The thread name is a meaningful C language string, whose length is restricted to 16 characters, including the terminating null byte. #include is needed for the resolution of EXIT_SUCCESS warning: implicit declaration of function ‘pthread_getname_np’ warning: implicit declaration of function ‘pthread_setname_np’ #define _GNU_SOURCE is needed for the resolution of the following warnings The following code, creates a pthread which later, it will give itself a meaningful name. Pthread_named_by_parent.c (compressed) (364 downloads)Įxample 1: The pthread decides for its name Pthread_self_named.c (compressed) (403 downloads) Naming a pthread using meaningful names, can be a very useful feature for debugging multi-threaded applications as it can make your logs very informative.įor this reason, we are presenting two examples demonstrating the use of names in pthreads. 29 September 2017 in C / C++ tagged _GNU_SOURCE / C/C++ / C++ / errno / pthread_create / pthread_getname_np / pthread_join / pthread_self / pthread_setname_np / pthread_t by Tux
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