ay use file descriptor based notifications. Please note that not all engines may support the callback mechanism, so the callback may not be used even if it has been set. See ASYNC_WAIT_CTX_new() for more details.</p>

<p>The ASYNC_block_pause() function will prevent the currently active job from pausing. The block will remain in place until a subsequent call to ASYNC_unblock_pause(). These functions can be nested, e.g. if you call ASYNC_block_pause() twice then you must call ASYNC_unblock_pause() twice in o