How to prevent unwanted DBG_FMMDM spam from filling up your logcat buffers I asked this question on Stack Overflow but was advised to ask it here.

I am attempting to debug an error using logcat in Android Studio on my testing device, a Galaxy s9 plus running Pie. Suddenly I have a really weird and annoying logcat output making it hard to view events:

2019-03-01 10:49:15.024 17645-17645/? I/DBG_FMMDM: [6.9.22][Line:55][a] xdmGetAccountRegistration : true
2019-03-01 10:49:15.024 17645-17645/? I/DBG_FMMDM: [6.9.22][Line:47][onDestroy] XDM ALERT REAMINED, SO RESTART DM SERVICE
2019-03-01 10:49:15.024 17645-17645/? I/DBG_FMMDM: [6.9.22][Line:2][a] FMM Application Start !
2019-03-01 10:49:15.028 17645-17645/? I/DBG_FMMDM: [6.9.22][Line:5][onCreate] XDM Service onCreate
2019-03-01 10:49:15.029 17645-17645/? I/DBG_FMMDM: [6.9.22][Line:20][onCreate] Device ID is null!!, service not start !
2019-03-01 10:49:15.030 17645-17645/? I/DBG_FMMDM: [6.9.22][Line:3][onStartCommand] 
2019-03-01 10:49:15.030 17645-17645/? I/DBG_FMMDM: [6.9.22][Line:2][onDestroy] onDestroy
2019-03-01 10:49:15.037 17645-17645/? I/DBG_FMMDM: [6.9.22][Line:30][a] Samsung Account Exist !!!
2019-03-01 10:49:15.038 17645-17645/? E/DBG_FMMDM: Warning!!! [6.9.22][Line:15][a] java.lang.NullPointerException: Attempt to read from field 'com.fmm.dm.b.a.x com.fmm.dm.b.a.ac.g' on a null object reference


This output runs over and over, to the point that my logcat is completely populated and there is no way to scroll up to see past outputs.

I'm sure it is some OS daemon, but I have never seen one that runs so frequently. 

I have no idea what I/DBG_FMMDM is and why it is attempting to read from com.fmm.dm.b.a.x (whatever that is).

Has anyone seen this type of output before?

My testing device is a Galaxy s9 plus running Pie
Yes, I have seen this before. It is a security feature and it is coming from Samsungs Find My Mobile {FMM}(com.samsung.android.fmm). Samsungs version of Google's Find My Device. 

It is located at:

Settings --> Lock screen (maybe Biometrics) and security --> Find My Mobile.

If the service is not wanted it can be deactivated.

I/DBG_FMMDM is short for Debug _ Find My Mobile Device Manager. 

A breakdown of what log you posted states: 

The FMM app is started but when it tries to get your Device ID it cannot find the IMEI for GSM and the MEID or ESN for CDMA phones so its returning null. However, when it checks to see if a Samsung account is connected to the device it returns positive.