How can I see which wakelocks are active

Question

For some reason my Android phone won't go to sleep. I assume that a wakelock is keeping it awake, but there is no way to tell which wakelocks are active. The running services doesn't list anything suspicious, and certainly nothing different from usual. So my questions are:

1. Does Android definitely release wakelocks when a process ends? Is it possible an app was badly written and didn't release a wakelock before exiting?

2. Is there any way to see the active wakelocks?

This is what dumpsys power shows:

$ dumpsys power Power Manager State:   mIsPowered=true mPowerState=0 mScreenOffTime=226093 ms   mPartialCount=0   mWakeLockState=   mUserState=   mPowerState=   mLocks.gather=   mNextTimeout=91922738 now=92136117 -213s from now   mDimScreen=true mStayOnConditions=0   mScreenOffReason=3 mUserState=0   mBroadcastQueue={-1,-1,-1}   mBroadcastWhy={0,0,0}   mPokey=1 mPokeAwakeonSet=false   mKeyboardVisible=false mUserActivityAllowed=false   mKeylightDelay=6000 mDimDelay=47000 mScreenOffDelay=7000   mPreventScreenOn=false  mScreenBrightnessOverride=-1  mButtonBrightnessOverride=-1   mScreenOffTimeoutSetting=60000 mMaximumScreenOffTimeout=2147483647   mLastScreenOnTime=0   mBroadcastWakeLock=UnsynchronizedWakeLock(mFlags=0x1 mCount=0 mHeld=false)   mStayOnWhilePluggedInScreenDimLock=UnsynchronizedWakeLock(mFlags=0x6 mCount=0 mHeld=false)   mStayOnWhilePluggedInPartialLock=UnsynchronizedWakeLock(mFlags=0x1 mCount=0 mHeld=false)   mPreventScreenOnPartialLock=UnsynchronizedWakeLock(mFlags=0x1 mCount=0 mHeld=false)   mProximityPartialLock=UnsynchronizedWakeLock(mFlags=0x1 mCount=0 mHeld=false)   mProximityWakeLockCount=0   mProximitySensorEnabled=false   mProximitySensorActive=false   mProximityPendingValue=-1   mLastProximityEventTime=0   mLightSensorEnabled=false   mLightSensorValue=-1.0 mLightSensorPendingValue=-1.0   mLightSensorScreenBrightness=35 mLightSensorButtonBrightness=255 mLightSensorKeyboardBrightness=0   mUseSoftwareAutoBrightness=true   mAutoBrightessEnabled=false   mScreenBrightness: animating=false targetValue=-1 curValue=0.0 delta=-1.3333334  mLocks.size=0:  mPokeLocks.size=1:     poke lock 'PhoneApp': POKE_LOCK_IGNORE_CHEEK_EVENTS 

Answer 1

In new versions of Android you can see list of wakelocks here:

adb shell "cat /sys/kernel/debug/wakeup_sources" 

Answer 2

You can use below adb command to require a wake lock

  adb shell "echo mylock > /sys/power/wake_lock" 

Then, you can use below command to watch if this lock is active. You will see the time column continuously change, it means the wake lock is active

  watch -n 1 'adb shell "cat /proc/wakelocks" | grep mylock' 

Now, use this adb command to release the wake lock

  adb shell "echo mylock > /sys/power/wake_unlock" 

Then, check it again, the time column will freeze, it means the wake lock is non active

  watch -n 1 'adb shell "cat /proc/wakelocks" | grep mylock' 

You can use the same technique to observe the wake lock you acquire in the code.