helper function to wait for the queue to not overflow/underload it

def _queue_wait(self):
		"""
		helper function to wait for the queue to not overflow/underload it
		"""
		
		if self.num_running_jobs >= self.job_queue_sizes[1]:
			while(self.num_running_jobs > self.job_queue_sizes[0]):
				self.logger.debug('HBMASTER: running jobs: %i, queue sizes: %s -> wait'%(self.num_running_jobs, str(self.job_queue_sizes)))
				self.thread_cond.wait()