pthread sleep linux

Question

I am creating a program with multiple threads using pthreads.

Is sleep() causing the process (all the threads) to stop executing or just the thread where I am calling sleep?

caf · Accepted Answer · 2020-07-04T06:45:27.547

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Just the thread. The POSIX documentation for sleep() says:

The sleep() function shall cause the calling thread to be suspended from execution...

edited Jul 04 '20 at 06:45

answered Sep 03 '10 at 04:47

caf

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Here's what "man 3 sleep" says: "sleep() makes the calling process sleep until seconds seconds have elapsed..." (Ubuntu 10). The function is in unistd.h. Is this documentation wrong or is there a second sleep function? – user48956 May 14 '12 at 17:42
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@user48956: For historical reasons, the man pages often use "process" where the behaviour now applies to the "thread" - this is the case in the `sleep(3)` man page that you refer to. I suggest submitting a bug to Ubuntu about the documentation. – caf May 15 '12 at 01:24

score 11 · Answer 2 · edited Jun 05 '15 at 11:18

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Try this,

#include <unistd.h>

usleep(microseconds);

edited Jun 05 '15 at 11:18

ANjaNA

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answered Jun 05 '15 at 03:36

Chand Priyankara

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Yep, that's easier to use than `nanosleep` in most cases. – Thomas Tempelmann Dec 20 '16 at 13:21
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Note that usleep() is obsolete and has been removed from POSIX.1-2008. You should use either sleep(), or nanosleep() if higher resolution is required. – dpi May 05 '18 at 21:27

score 6 · Answer 3 · answered Sep 29 '11 at 08:21

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I usually use nanosleep and it works fine. Nanosleep supends the execution of the calling thread. I have had the same doubt because in some man pages sleep refers to the entire process.

answered Sep 29 '11 at 08:21

CMorgan

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Basile Starynkevitch · Answer 4 · 2020-07-04T10:29:30.520

In practice, there are few cases where you just want to sleep for a small delay (milliseconds). For Linux, read time(7), and see also this answer. For a delay of more than a second, see sleep(3), for a small delay, see nanosleep(2). (A counter example might be a RasPerryPi running some embedded Linux and driving a robot; in such case you might indeed read from some hardware device every tenth of seconds). Of course what is sleeping is just a single kernel-scheduled task (so a process or thread).

It is likely that you want to code some event loop. In such a case, you probably want something like poll(2) or select(2), or you want to use condition variables (read a Pthread tutorial about pthread_cond_init etc...) associated with mutexes.

Threads are expensive resources (since each needs a call stack, often of a megabyte at least). You should prefer having one or a few event loops instead of having thousands of threads.

If you are coding for Linux, read also Advanced Linux Programming and syscalls(2) and pthreads(7).

score 0 · Answer 5 · answered Nov 13 '22 at 11:32

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Posix sleep function is not thread safe. https://clang.llvm.org/extra/clang-tidy/checks/concurrency/mt-unsafe.html

answered Nov 13 '22 at 11:32

rjhcnf

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score -5 · Answer 6 · answered Oct 30 '18 at 14:27

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sleep() function does not cease a specific thread, but it stops the whole process for the specified amount of time. For stopping the execution of a particular thread, we can use one pthread condition object and use pthread_cond_timedwait() function for making the thread wait for a specific amount of time. Each thread will have its own condition object and it will never receive a signal from any other thread.

answered Oct 30 '18 at 14:27

Ricky

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This is inaccurate. The `sleep()` will cause the current thread to sleep. See `sleep(3)`. Lots of older man pages still use the word "process," but in reality a thread is a process. – Will Eccles Jun 08 '20 at 15:46

pthread sleep linux

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