zephyr

History

Daniel Leung ee40548788 samples: condvar: extra stack space for custom threads When coverage is enabled, some boards require more stack space for the custom threads created in main(). Since this "samples" already has CONFIG_TEST enabled, we can pad the stack size with CONFIG_TEST_EXTRA_STACK_SIZE. Signed-off-by: Daniel Leung <daniel.leung@intel.com>		2022-08-18 17:23:18 +02:00
..
src	samples: condvar: extra stack space for custom threads	2022-08-18 17:23:18 +02:00
CMakeLists.txt
prj.conf
README.rst	samples: kernel: condvar: add README	2022-07-08 21:06:33 -04:00
sample.yaml

README.rst

.. _samples_kernel_condvar:

Condition Variables
###################

Overview
********

This sample demonstrates the usage of condition variables in a
multithreaded application. Condition variables are used with a mutex
to signal changing states (conditions) from one thread to another
thread. A thread uses a condition variable to wait for a condition to
become true. Different threads alternate between their entry point
function execution based on when they signal the other thread that is
pending on the condition variable. The sample can be used with any
:ref:`supported board <boards>` and prints the sample output shown to
the console.

Building and Running
********************

This application can be built and executed on Native Posix as follows:

.. zephyr-app-commands::
   :zephyr-app: samples/kernel/condition_variables/condvar
   :host-os: unix
   :board: native_posix
   :goals: run
   :compact:

To build for another board, change "native_posix" above to that board's name.

Sample Output
=============

.. code-block:: console

    Starting watch_count: thread 1
    watch_count: thread 1 Count= 0. Going into wait...
    inc_count: thread 2, count = 1, unlocking mutex
    inc_count: thread 3, count = 2, unlocking mutex
    inc_count: thread 2, count = 3, unlocking mutex
    inc_count: thread 3, count = 4, unlocking mutex
    inc_count: thread 2, count = 5, unlocking mutex
    inc_count: thread 3, count = 6, unlocking mutex
    inc_count: thread 2, count = 7, unlocking mutex
    inc_count: thread 3, count = 8, unlocking mutex
    inc_count: thread 2, count = 9, unlocking mutex
    inc_count: thread 3, count = 10, unlocking mutex
    inc_count: thread 2, count = 11, unlocking mutex
    inc_count: thread 3, count = 12  Threshold reached.Just sent signal.
    inc_count: thread 3, count = 12, unlocking mutex
    watch_count: thread 1 Condition signal received. Count= 12
    watch_count: thread 1 Updating the value of count...
    watch_count: thread 1 count now = 137.
    watch_count: thread 1 Unlocking mutex.
    inc_count: thread 2, count = 138, unlocking mutex
    inc_count: thread 3, count = 139, unlocking mutex
    inc_count: thread 2, count = 140, unlocking mutex
    inc_count: thread 3, count = 141, unlocking mutex
    inc_count: thread 2, count = 142, unlocking mutex
    inc_count: thread 3, count = 143, unlocking mutex
    inc_count: thread 2, count = 144, unlocking mutex
    inc_count: thread 3, count = 145, unlocking mutex
    Main(): Waited and joined with 3 threads. Final value of count = 145. Done.