Finding cause in LeakCanary leak trace

Question

LeakCanary has reported a memory leak in our app with following leak trace:

05-24 08:41:05.380044 16534 19408 D LeakCanary: HeapAnalysisSuccess(heapDumpFile=/data/user/0/..../files/leakcanary/2020-05-24_08-24-07_502.hprof, createdAtTimeMillis=1590334865374, analysisDurationMillis=85525, applicationLeaks=[ApplicationLeak(className=<>.media.MediaControlActivity, leakTrace=
05-24 08:41:05.380044 16534 19408 D LeakCanary: ┬
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ android.provider.FontsContract
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: NO (HomeApplication↓ is not leaking and a class is never leaking)
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    GC Root: System class
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ static FontsContract.sContext
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ <>.application.HomeApplication
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: NO (Application is a singleton)
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    HomeApplication does not wrap an activity context
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ HomeApplication.mLoadedApk
05-24 08:41:05.380044 16534 19408 D LeakCanary: │                      ~~~~~~~~~~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ android.app.LoadedApk
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ LoadedApk.mReceivers
05-24 08:41:05.380044 16534 19408 D LeakCanary: │                ~~~~~~~~~~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ android.util.ArrayMap
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ ArrayMap.mArray
05-24 08:41:05.380044 16534 19408 D LeakCanary: │               ~~~~~~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ java.lang.Object[]
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ array Object[].[9]
05-24 08:41:05.380044 16534 19408 D LeakCanary: │                     ~~~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ android.util.ArrayMap
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ ArrayMap.mArray
05-24 08:41:05.380044 16534 19408 D LeakCanary: │               ~~~~~~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ java.lang.Object[]
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ array Object[].[58]
05-24 08:41:05.380044 16534 19408 D LeakCanary: │                     ~~~~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ ayf
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ ayf.a
05-24 08:41:05.380044 16534 19408 D LeakCanary: │          ~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ ayg
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ ayg.b
05-24 08:41:05.380044 16534 19408 D LeakCanary: │          ~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ als
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ als.b
05-24 08:41:05.380044 16534 19408 D LeakCanary: │          ~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ alt
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ alt.b
05-24 08:41:05.380044 16534 19408 D LeakCanary: │          ~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ╰→ <>.media.MediaControlActivity
05-24 08:41:05.380044 16534 19408 D LeakCanary: ​     Leaking: YES (Activity#mDestroyed is true and ObjectWatcher was watching this)
05-24 08:41:05.380044 16534 19408 D LeakCanary: ​     key = 758a249e-d3c7-44e3-b633-4649a5574735
05-24 08:41:05.380044 16534 19408 D LeakCanary: ​     watchDurationMillis = 5397
05-24 08:41:05.380044 16534 19408 D LeakCanary: ​     retainedDurationMillis = 393
05-24 08:41:05.380044 16534 19408 D LeakCanary: , retainedHeapByteSize=43842), ApplicationLeak(className=aym, leakTrace=
05-24 08:41:05.380044 16534 19408 D LeakCanary: ┬

from this, I understand that the cause is somewhere in MediaControlActivity. Also, I see that the reference being stored starts in the Application class/

But what I don't understand is how these two are linked, since some lines in the trace are kind of obfuscated, this part specifically:

├─ java.lang.Object[]
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ array Object[].[58]
05-24 08:41:05.380044 16534 19408 D LeakCanary: │                     ~~~~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ ayf
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ ayf.a
05-24 08:41:05.380044 16534 19408 D LeakCanary: │          ~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ ayg
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ ayg.b
05-24 08:41:05.380044 16534 19408 D LeakCanary: │          ~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ als
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ als.b
05-24 08:41:05.380044 16534 19408 D LeakCanary: │          ~
05-24 08:41:05.380044 16534 19408 D LeakCanary: ├─ alt
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    Leaking: UNKNOWN
05-24 08:41:05.380044 16534 19408 D LeakCanary: │    ↓ alt.b
05-24 08:41:05.380044 16534 19408 D LeakCanary: │          ~

So, the questions that I have are: - why is the trace obfuscated here? Is is due to proguard? If not, what else?

Answer 1

The trace is obfuscated because the code is obfuscated. If you enabled Proguard for that build, there's a plugin to help LeakCanary: https://square.github.io/leakcanary/recipes/#using-leakcanary-with-obfuscated-apps

If you did not enable Proguard, then it's most likely because you use a library that has been obfuscated. You should try to figure out which library it is.