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I've experienced seen this issue, even on 26.0.0-beta1.

Thank you for reporting this issue. We have shared this with our engineering team and will update this issue with more information as it becomes available.

I think I'm running into this issue again--but this time it's with deep-linking and synthesizing a fragment back stack. If I have postponeEnterTransition in the fragment I'm deep-linking to, I see the other (backstacked) fragments briefly show on screen.

In one project, I'm using the Navigation Component. The graph is just two fragments: A1 is the start destination with a deep-link to A2. I see A1 show momentarily if I use postponeEnterTransition in A2. And I see similar results in another project that does its own fragment transactions; in that case, I can use setReorderingAllowed(false) to prevent the issue.

Here's my project to test

related: b/63325506

we can probably tie this to WAL support.

So the title of this bug should be changed to "support multiple instances of RoomDatabase"?

When support this? i face the same problem, it multiple query and insert, it'll block

hopefully we'll have this in 2.1 . What is your use case, are you accessing the same database from different processes or are you creating 2 instance of the same RoomDatabase in the same process?

Create one instance of RoomDatabase, and use LiveData paging query the datas and when querying, i also use the db connect insert the data, the query always wait the insert end and return

BTW, other thread insert the data, or update the data

if you are in the same process, don't use multiple RoomDatabase instances.

Why the LiveData been blocked? the query always waiting for the insert end and return

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 41bbdfb46058e7ef3ea6aa21ac8d7a3c7642fa1d
Author: Yuichi Araki <yaraki@google.com>
Date:   Wed May 23 17:38:58 2018

    Multi-instance invalidation
   
    Developers can now sync observers for InvalidationTracker and LiveData
    between multiple RoomDatabase instances by
    RoomDatabase.Builder.enableMultiInstanceInvalidation(). This can also be
    used for database instances in other processes. All the instances have
    to be using the same database file.
   
    When multi-instance invalidation is turned on, all the tables are
    observed by an instance of MultiInstanceInvalidationClient, and
    invalidation detected in one instance is broadcast to other instances by
    remote procedure call.
   
    Test: MultiInstanceInvalidationTest
    Bug: 62334005
    Bug: 80464228
    Change-Id: I76033c5ac543ddaef735be06f828b7d7d607883a

M       room/integration-tests/testapp/build.gradle
A       room/integration-tests/testapp/src/androidTest/java/androidx/room/integration/testapp/test/MultiInstanceInvalidationTest.java
M       room/integration-tests/testapp/src/main/AndroidManifest.xml
A       room/integration-tests/testapp/src/main/aidl/androidx/room/integration/testapp/ISampleDatabaseService.aidl
A       room/integration-tests/testapp/src/main/java/androidx/room/integration/testapp/SampleDatabaseService.java
M       room/integration-tests/testapp/src/main/java/androidx/room/integration/testapp/database/CustomerDao.java
A       room/integration-tests/testapp/src/main/java/androidx/room/integration/testapp/database/Product.java
A       room/integration-tests/testapp/src/main/java/androidx/room/integration/testapp/database/ProductDao.java
M       room/integration-tests/testapp/src/main/java/androidx/room/integration/testapp/database/SampleDatabase.java
M       room/runtime/api/current.txt
M       room/runtime/src/main/AndroidManifest.xml
A       room/runtime/src/main/aidl/androidx/room/IMultiInstanceInvalidationCallback.aidl
A       room/runtime/src/main/aidl/androidx/room/IMultiInstanceInvalidationService.aidl
M       room/runtime/src/main/java/androidx/room/DatabaseConfiguration.java
M       room/runtime/src/main/java/androidx/room/InvalidationTracker.java
A       room/runtime/src/main/java/androidx/room/MultiInstanceInvalidationClient.java
A       room/runtime/src/main/java/androidx/room/MultiInstanceInvalidationService.java
M       room/runtime/src/main/java/androidx/room/RoomDatabase.java
M       room/testing/src/main/java/androidx/room/testing/MigrationTestHelper.java

https://android-review.googlesource.com/720919
https://goto.google.com/android-sha1/41bbdfb46058e7ef3ea6aa21ac8d7a3c7642fa1d