def _format_counters(counters, indent='\t'):
    """Convert a map from group -> counter name -> amount to a message
    similar to that printed by the Hadoop binary, with no trailing newline.
    """
    num_counters = sum(len(counter_to_amount)
                       for group, counter_to_amount in counters.items())
    message = 'Counters: %d' % num_counters

    for group, group_counters in sorted(counters.items()):
        if group_counters:
            message += '\n%s%s' % (indent, group)
            for counter, amount in sorted(group_counters.items()):
                message += '\n%s%s%s=%d' % (indent, indent, counter, amount)

    return message