WordPress at a glance
action is not described

action_scheduler_before_process_queue action-hook . WC 1.0

Process actions in the queue.

Usage

add_action( 'action_scheduler_before_process_queue', 'action_function_name_1487' );
function action_function_name_1487(){
	// action...
}

Where the hook is called

ActionScheduler_WPCLI_QueueRunner::run()
action_scheduler_before_process_queue
ActionScheduler_QueueRunner::run()
action_scheduler_before_process_queue
woocommerce/packages/action-scheduler/classes/ActionScheduler_QueueRunner.php 126
do_action( 'action_scheduler_before_process_queue' );

Where in WP core the hook is used WooCommerce

woocommerce/packages/action-scheduler/classes/data-stores/ActionScheduler_wpCommentLogger.php 219
add_action( 'action_scheduler_before_process_queue', array( $this, 'disable_comment_counting' ), 10, 0 );