Pthread Error Codes 11

to the Single Unix Specification standard consisted to submit an example of use for pthread_sigmask()[1]. Since my proposal was going to be viewed by many Austin Group's contributors (some being "recognized how to find pthread_threads_max UNIX authority"), I tried to make my example as perfect as possible.

Pthread Error Handling

In an academic fashion, I checked every function's return code for possible errors. That's where I got it wrong pthread error codes to string for the Pthreads APIs. Oh well, they do not use errno… The Problem: Before the advent of Pthreads, POSIX functions used to return -1 on error, and set the corresponding error return code from pthread_create is 11 error detail resource temporarily unavailable error code in the global variable errno[2]. This mechanism has a few drawbacks even for single-threaded process: it is not simple to return -1 as valid value. a signal handler may change the errno value between the point a function set errno, and the point where you check the errno variable. Of course, a global errno doesn't work for multi-threaded processes. Indeed,

How To Find Pthread_threads_max Ubuntu

a thread could execute a function that modifies errno just before you check the value in another thread. The (Pthreads) Solution: Since Pthreads, the errno variable is thread-local. That is, every thread has its own "errno copy". If you (or a system function) set the errno variable in one thread, it won't affect the errno value in any other thread. This is shown in the example below. Download errno_01.c1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 /*------------------------------ errno_01.c -------------------------------* compile with: cc -pthread errno_01.c -o errno_01 Copyright Loic Domaigne. Licensed under the Apache License, Version 2.0. *--------------------------------------------------------------------------*/ #include // sleep() #include #include #include #include // strerror() #include /***************************************************************************/

is 8MB. pthread_detach() is important to release thread resource so that it can be reclaimed. I had this program running with 115 threads, and pthread_create return there were many others dynamically created during runtime. At some point, pthread_create resource temporarily unavailable I noticed these dynamic threads were not created properly, it took me a while to figure out the

Pthread_create Example

problem was on pthread_create() which returned error code 11: Resource temporarily unavailable. I searched through the Internet and manuals trying to figure out what is the maximum number of http://www.domaigne.com/blog/computing/pthreads-errors-and-errno/ threads supported in a process, and it seemed there was no hard limit on this. So I decided to run a small test with the follow piece of code. #include #include #include #include void* thread_proc(void *param) { usleep(10); return NULL; } int main(int argc, char* argv[]) { pthread_t test_thead; for(int i=1; i<10000; i++){ int error https://zhenprogramming.wordpress.com/2009/08/27/max-number-of-threads/ = pthread_create(&test_thead, NULL, &thread_proc, NULL); if (error){ printf("pthread_create fail in creating thread %d with code: %d\n", i, error); break; } } return 0; } And the test result showed pthread_create failed creating thread 382 (for some reason, it may be 381 or 383, but 382 turned up most of the time). So my guess would be 384 threads is the limit. Late on, I came to realize that there is a default stack space for a thread, which is about 8 MB, so 384x8M=3GB, a fair limit in a 32-bit system. However, what bugged me was I definitely didn't have ~380 threads running at the same time. In the above test program, even if I added sleep(1) after pthread_create(), such that every created thread was guaranteed to be over by the time out, I still couldn't increase the number. After searching for a while, I had learnt pthread_detach() or pthread_join() is needed if you need thread resource to be reclaimed. Here was what it said: The pthread_detach() function is used to indicate to the implemen

void *(*start_routine)(void*), void *arg); DESCRIPTION The pthread_create() function is used to create a new thread, with attributes specified by attr, within a process. If attr is NULL, the default attributes http://pubs.opengroup.org/onlinepubs/7908799/xsh/pthread_create.html are used. If the attributes specified by attr are modified later, https://groups.google.com/d/topic/raxml/QFOc5ZIe3b0 the thread's attributes are not affected. Upon successful completion, pthread_create() stores the ID of the created thread in the location referenced by thread. The thread is created executing start_routine with arg as its sole argument. If the start_routine returns, the effect is as if there pthread error was an implicit call to pthread_exit() using the return value of start_routine as the exit status. Note that the thread in which main() was originally invoked differs from this. When it returns from main(), the effect is as if there was an implicit call to exit() using the return value of main() as the exit status. The pthread error codes signal state of the new thread is initialised as follows: The signal mask is inherited from the creating thread. The set of signals pending for the new thread is empty. If pthread_create() fails, no new thread is created and the contents of the location referenced by thread are undefined. RETURN VALUE If successful, the pthread_create() function returns zero. Otherwise, an error number is returned to indicate the error. ERRORS The pthread_create() function will fail if: [EAGAIN] The system lacked the necessary resources to create another thread, or the system-imposed limit on the total number of threads in a process PTHREAD_THREADS_MAX would be exceeded. [EINVAL] The value specified by attr is invalid. [EPERM] The caller does not have appropriate permission to set the required scheduling parameters or scheduling policy. The pthread_create() function will not return an error code of [EINTR]. EXAMPLES None. APPLICATION USAGE None. FUTURE DIRECTIONS None. SEE ALSO pthread_exit(), pthread_join(), fork(), . DERIVATION Derived from the POSIX Threads Extension (1003.1c-1995) UNIX is a registered

GoogleВойтиСкрытые поляПоиск групп или сообщений