Running pipelines in parallel.

def run_matrix_in_parallel(self, process_data):
        """Running pipelines in parallel."""
        worker_data = [{'matrix': entry, 'pipeline': process_data.pipeline,
                        'model': process_data.model, 'options': process_data.options,
                        'hooks': process_data.hooks} for entry in self.matrix
                       if Matrix.can_process_matrix(entry, process_data.options.matrix_tags)]
        output = []
        success = True
        with closing(multiprocessing.Pool(multiprocessing.cpu_count())) as pool:
            for result in pool.map(matrix_worker, worker_data):
                output += result['output']
                if not result['success']:
                    success = False
        return {'success': success, 'output': output}