Recently after every upload I get "IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long period of time."

[nicolas-raoul]

It started this week, probably caused by a recent commit?

Tasks:

1. Reproduce the issue
2. Find since what commit it started (use git bisect)
3. Either revert the commit or improve it.

If you can upload without any such issue please let me know. Thanks! :-)

java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long period of time.
at androidx.room.RoomDatabase.assertNotMainThread(RoomDatabase.kt:435)
at androidx.room.RoomDatabase.beginTransaction(RoomDatabase.kt:505)
at fr.free.nrw.commons.customselector.database.UploadedStatusDao_Impl.insert(UploadedStatusDao_Impl.java:120)
at fr.free.nrw.commons.customselector.database.UploadedStatusDao.insertUploaded(UploadedStatusDao.kt:51)
at fr.free.nrw.commons.upload.worker.UploadWorker$saveIntoUploadedStatus$1$1.invokeSuspend(UploadWorker.kt:538)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:108)
at android.os.Handler.handleCallback(Handler.java:991)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loopOnce(Looper.java:232)
at android.os.Looper.loop(Looper.java:317)
at android.app.ActivityThread.main(ActivityThread.java:8787)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:591)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:871)
Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@7cb3322, Dispatchers.Main]

[rohit9625]

I want to take this one. Well, I am experiencing this error when I tried to build the app using the latest Android Studio. Do you have any idea about this?

[rohit9625]

When I try to open the custom selector and open a folder, I get this crash:

I guess the issue is with accessing database. I am looking into it.

[rohit9625]

This commit removes the suspend keyword from UploadStatusDao making it blocking functions, i.e., it'll block the thread from where these functions will be called. In ImageLoader and UploadWorker, one of the DAO's methods was called from MainScope() that's why we are facing that error.
However, I added the suspend keyword again and removed the MainScope with CoroutineScope.

I will link a PR once assigned :)

[RitikaPahwa4444]

Hey @rohit9625, the commit removes suspend keyword from DepictsDao as well. Did you notice any issues because of that too during testing?

[rohit9625]

Sorry, I didn't notice that before. The changes are in the PlacesDao also. However, in the Depicts Dao, the function calls to the database is handled like this:

private suspend fun deleteDepicts(depicts: Depicts) =
        CoroutineScope(Dispatchers.IO).launch {
            delete(depicts)
        }

But, I need to cross-check for usages of functions in DepictsDao. Or should revert the changes because those functions are meant to be thread-safe? Currently, they are blocking the IO thread.

[rohit9625]

Okay, I will revert the changes. Since there's no sense in using CoroutineScope(Dispatcher. IO) in the context of DepictsDao. Because, if some other operation is executing on the IO thread and somehow we perform a task that executes the functions from DepictsDao, then it'll affect the execution of other tasks on the thread.

Thank you for pointing out @RitikaPahwa4444

[sivaraam]

Reopening as the fix in MR #5902 seems incomplete according to this comment.

[rohit9625]

Hey @nicolas-raoul, should I create a new PR, or will pushing commits to the existing PR's branch be sufficient?

[nicolas-raoul]

Either is fine. 🙂