Change deleteIdleStats default value from false to true

[ziegeer]

Statsd has a deleteIdleStats option that is responsible for removing unused statistics. The default value is false, which means once statsd has seen a stat, it will repeatedly send it forever regardless of weather it sees that stat come in again. I propose a default value of true, which is far less likely to cause harm. In practice, stat names change regularly and I've seen this feature cause more than 500,000 unused, worthless stats to be sent to a single Graphite instance every five seconds without end. Even a well-spec'd Graphite instance can struggle to keep up with that volume of data, especially since that's not including the actual live data that people want. Graphite does not include good facilities for identifying where a given stat comes from so identifying statsd as the source of the flood of stats took many man-hours. Please save many headaches and remove unused stats by default by setting deleteIdleStats to true out of the box.

[mrtazz]

Thanks for the patch! We have thought about that before, however it's a breaking change with the current configuration and therefore we will postpone it into the v1.0.0 release for which we have a couple of other breaking changes that we want to do.