Understanding, Debugging and Fixing
Power Bugs
Aditya & Satyam
Power Bugs
Apps are to blame the most for bad battery life
Power Bugs
• Bad coding patterns cause power bugs
• Specific behaviors of the Android Platform
• App inter-dependencies!
• Special Attention must be paid to optimize for power!
Users Hate Power Bugs
Understanding Common Power Bugs
Common Power Bugs 1. Not Sleeping Properly
Common Power Bugs 2. Un-necessary Animations
Common Power Bugs 3. Updating the Screen
Common Power Bugs 4. Handling Display-Off
Common Power Bugs 5. Waking up to notifications
More Types Of Power Bugs
• Registering for un-necessary events
• Waking up the system causes everyone to be woken up
• Register for “active” notifications (instead of passive ones)
• Handset-specific problems
Best Practices(or how to avoid the dreaded battery drain)
Power Consumption is Complex and Inter-dependent among components
Jeff Sharkey at Google IO
Best Practices - Network
• prefetch data
– to avoid switching states frequently, try and read as much data as possible
– trade-off between too much pre-fetch and battery drain
– google recommends pre-fetching data that you will initiate in the next 2 to 5 minutes, and in the order of 1-5 MB size
• batch data
– do data send/receive in batches rather than on-demand
– eg: batch analytics information, rather than sending them as they are collected
Best Practices - Network
• using inexact timers
– AlarmManager.setInexactRepeating()
– use ELAPSED_REALTIME instead of ELAPSED_REALTIME_WAKEUP
• detect network connection
– avoid connection attempts if no network is active
• avoid polling and use GCM when possible
– avoids multiple connections
– reduces the number of device state changes
Best Practices - Screen
• color matters!
– esp on OLED screens
– darker the color, lesser the consumption
• brightness levels have more impact
– refer to - http://stackoverflow.com/questions/5032588/cant-apply-system-screen-brightness-programmatically-in-android
Best Practices - Screen
• programmatically reduce brightness if its suits your app/activity
• Use “night mode” for reading Apps
• Think about your color scheme
Best Practices - CPU
• wakelocks are your friend, but your users worst nightmare!
• use them only if really needed and ensure they are removed as soon as possible
• Use ‘android:keepScreenOn’ property in your manifest instead of doing it programmatically
Best Practices - CPU
• if possible, spread out your computationally intensive job
• gpu typically consumes more power than cpu
– avoid floating point math where possible
• use algorithms that consume less CPU cycle
– O(n log n) vs O(n 2) algorithms
Identifying power bugs with little eye
Demo
