GreenDroid Research Project
Contact: andrewust@cse.ust.hk

Problems detected by GreenDroid

1. Existing problems

GreenDroid detected 12 energy problems that were confirmed before our experiments. These problems are:

Application name	Energy problem	Problematic version	Problem type
DroidAR	Issue 27	Revision 204	Missing sensor deactivation
Recycle Locator	Issue 33	Revision 68	Missing sensor deactivation
Ushahidi	Commit 337b48f	Revision 9d0aa75	Missing sensor deactivation
Sofia Public Trasport Nav.	Issue 76	Revision eb4fbcb (115)	Missing sensor deactivation
AndTweet	Issue 29	Version 0.2.4	Missing wake lock deactivation
EbookDroid	Issue 23	Revision 137	Missing wake lock deactivation
BabbleSink	Commit 9fbc6f0	Revision 12879a3	Missing wake lock deactivation
CWAC-Wakeful	Commit c7d440f	Revision d984b89	Missing wake lock deactivation
Sofia Public Transport Nav.	Issue 38	Revision 7959b87 (114)	Sensory data underutilization
Osmdroid	Issue 53	Revision 750	Sensory data underutilization
Zmanim	Issue 50/56	Revision 322	Sensory data underutilization
Geohash Droid	Issue 24	Version 0.8.1-pre2	Sensory data underutilization

These problems are known to cause huge energy waste and great inconvenience for users. Below are two user reviews for Zmanim and Geohash Droid, respectively.

2. New problems

GreenDroid also detected two new energy problems that were previously unknown. We then submitted bug reports to developers and the two bugs have been confirmed by developers.

Application name	Energy problem	Problematic version	Problem type
Omnidroid	Issue 179	Revision 863	Sensory data underutilization
GPSLogger	Issue 7	Revision 15	Sensory data underutilization

Below are two comments from developers for Omnidroid issue 179 and GPSLogger issue 7, respectively.

Omnidroid: "Completely true, and your suggestion is a great idea and you're correct omnidroid does suck up way more energy than necessary as a result.  I'd be happy to accept a patch in this regard."

GPSLogger: "Why would someone keep polling GPS if the location data are continuously discarded? GPS is an energy hog! The current design is far from perfect."

We also created a patch for GPSLogger to optimize its energy consumption. We did some field testing of our patch and the result suggested that there is around 20% energy saving. Although this saving is not too much, considering users typically concurrently run multiple applications on their smartphone, it is still meaningful if the energy consumption for each application can be reduced by 20%. This patch was later integrated into GPSLogger and a new version can be downloaded here.