Hello. Thanks for replying. No. There is no crash, just illegal instruction. And it happens after the function run over. After recheck the document, https://www.boost.org/doc/libs/1_63_0/doc/html/boost_asio/using.html BOOST_ASIO_DISABLE_THREADS Explicitly disables Boost.Asio's threading support, independent of whether or not Boost as a whole supports threads. I find by -DBOOST_ASIO_DISABLE_THREADS the code works fine. Still don't know why On Thu, Dec 21, 2023 at 2:35 AM Ruben Perez wrote:

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The code looks like below: void myTask(const char *text) { sleep(5); /*for(;;) { //sleep(1); }*/ cout<<"text is "<

Does the problem happen if you call any function other than sleep? Doing a blocking sleep in an async task is something to avoid in general. It may be causing interferences with asio's internal scheduler.

Hi Ruben. Thanks for replying. The problem is not within sleep. I used sleep to identify where the code got illegal instruction then got killed. The problem, as I described, is that without DBOOST_ASIO_DISABLE_THREADS, it happened after the function ran over. Instead of returning peacefully, got "illegal instruction" error. I think the problem is because the old kernel and gcc I used, the device was made in 2009 so the system is quite old. Besides this , if I use '-fPIC' which gcc, the program crashed either. On Thu, Dec 21, 2023 at 10:39 PM Ruben Perez wrote:

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BOOST_ASIO_DISABLE_THREADS

Explicitly disables Boost.Asio's threading support, independent of whether or not Boost as a whole supports threads.

I find by -DBOOST_ASIO_DISABLE_THREADS the code works fine.

From the Linux man pages: https://man7.org/linux/man-pages/man3/sleep.3.html sleep is listed as MT-unsafe.

From this thread: https://unix.stackexchange.com/questions/528362/sleep-system-call-on-linux-i... This behaviour is used as a workaround for a bug that is still present in the Linux version you're using. Calling a MT-unsafe function from a multi-threaded environment can yield to behaviour like the one you're describing. Can you please replace the sleep call by a nanosleep (https://man7.org/linux/man-pages/man2/nanosleep.2.html), which is MT-safe (or a console print statement), and see if the behaviour reproduces?

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Still don't know why

On Thu, Dec 21, 2023 at 2:35 AM Ruben Perez wrote:

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The code looks like below: void myTask(const char *text) { sleep(5); /*for(;;) { //sleep(1); }*/ cout<<"text is "<

Does the problem happen if you call any function other than sleep? Doing a blocking sleep in an async task is something to avoid in general. It may be causing interferences with asio's internal scheduler.