Removal of visible item may result in showing an unexpected item [154124815]

Fixed

Bug

Status Update

No update yet.

Description

je...@google.com

created issue #1

Apr 15, 2020 06:07PM

When items are same size as the viewport, and RV is currently laid out such that the viewport shows exactly one complete item, and you remove that item from the dataset, it can't find a reference child that is in the viewport. It defaults to using the first child it found in the hierarchy (getChild(0) for regular LTR RVs) as the reference child. But then it doesn't seem to use that child's old position as the anchor position, but just places that child at the start of the viewport.

That is a problem if you are looking at the last item (item N) and have two extra items laid out before the visible one. You'd expect that if you remove item N, you will look at item N-1 after that. But, it will actually go to item N-2.

I didn't check the behavior if you're not looking at the last item, but that might be affected as well.

Comments

sh...@google.com <sh...@google.com> #2Apr 15, 2020 10:09PM

A couple of questions:

1. Have you saw crash in real device or only in simulators?
2. Do you use dynamic feature for language ID?

sh...@google.com <sh...@google.com> #3Apr 15, 2020 10:09PM

Reassigned to je...@google.com.

Tested on Android 12 Emulator with custom executor, but cannot repro this issue.

sh...@google.com <sh...@google.com> #4Apr 15, 2020 10:11PM

Second crash in the description is from a real device. Experienced it myself on two different Xiaomi phones, plus lots of crashes from users in the Google Play console.
Dynamic features are not used in the application.

As a wild guess, I have downgraded build tools from 31.0.0 to 30.0.3, compileSdk from 31 to 30, and moved all work with Language ID to the service in a separate process (just to be sure that crash can kill secondary process instead of main). This combination is in beta for 2 days by now and I don't see any SIGSEGV crashes.

je...@google.com <je...@google.com> #5Apr 16, 2020 09:40AM

Hmm, I feel the crash might be something related to separate/secondary process.

I also changed compileSdk and targetSDK to 31 but still cannot repro this issue.

ap...@google.com <ap...@google.com> #6May 4, 2020 11:13PM

On the contrary, there was no separate process before, when crashes started.

In the new build (with the aforementioned changes) I can see SIGSEGV crash, but only one instead of dozens and it has a bit different backtrace:

signal 11 (SIGSEGV), code 1 (SEGV_MAPERR)
liblanguage_id_jni.so (offset 0x11e000)

backtrace:
  #00  pc 000000000003c7c0  /data/app/azagroup.reedy-mF7zTu2bv_ELlbFArwNgqA==/split_config.arm64_v8a.apk!lib/arm64-v8a/liblanguage_id_jni.so (offset 0x11e000)
  #00  pc 000000000003b960  /data/app/azagroup.reedy-mF7zTu2bv_ELlbFArwNgqA==/split_config.arm64_v8a.apk!lib/arm64-v8a/liblanguage_id_jni.so (offset 0x11e000)
  #00  pc 000000000003bb48  /data/app/azagroup.reedy-mF7zTu2bv_ELlbFArwNgqA==/split_config.arm64_v8a.apk!lib/arm64-v8a/liblanguage_id_jni.so (offset 0x11e000)
  #00  pc 000000000003bafc  /data/app/azagroup.reedy-mF7zTu2bv_ELlbFArwNgqA==/split_config.arm64_v8a.apk!lib/arm64-v8a/liblanguage_id_jni.so (offset 0x11e000)
  #00  pc 0000000000036c98  /data/app/azagroup.reedy-mF7zTu2bv_ELlbFArwNgqA==/split_config.arm64_v8a.apk!lib/arm64-v8a/liblanguage_id_jni.so (offset 0x11e000)
  #00  pc 0000000000032714  /data/app/azagroup.reedy-mF7zTu2bv_ELlbFArwNgqA==/split_config.arm64_v8a.apk!lib/arm64-v8a/liblanguage_id_jni.so (offset 0x11e000)
  #00  pc 0000000000031cac  /data/app/azagroup.reedy-mF7zTu2bv_ELlbFArwNgqA==/split_config.arm64_v8a.apk!lib/arm64-v8a/liblanguage_id_jni.so (offset 0x11e000)
  #00  pc 0000000000057438  /data/app/azagroup.reedy-mF7zTu2bv_ELlbFArwNgqA==/oat/arm64/base.odex (offset 0x57000)

sh...@google.com <sh...@google.com> May 8, 2020 08:40PM

Marked as fixed.

ch...@gmail.com <ch...@gmail.com> #7Jan 6, 2021 04:13PM

FYI, ML Kit launched a new language ID SDK in the latest release, which uses a new language ID model. https://developers.google.com/ml-kit/release-notes#august_11_2021

Could you try the new SDK version(17.0.0) to check if you can still repro this native crash? Thanks!