@staticmethod
def parse_resource_usage_header(header):
    """parse string like WORKER_TIME-3600=11.7/10000000;DB_QUERY_TIME-21600=4.62/2000 into dict
        """
    if not header:
        return {}
    result = {}
    try:
        for line in header.split(';'):
            right, left = line.split('=')
            metric, time_span = right.split('-')
            used, limit = left.split('/')
            result.setdefault(metric, {}).setdefault(time_span, {})[limit
                ] = float(used)
    except ValueError:
        return {}
    return result
