Amalgamation for android arm64 was built successfully but failed to run in device

[zhenglaizhang]

Environment info

Operating System: Arch Linux (build host)
Targeting Device: Android 7.0 with arm64-v8a CPU

Compiler:

• Android toolchain produced from python make_standalone_toolchain.py --arch arm64 --install-dir /tmp/my-android-toolchain --stl=libc++
• Latest NDK (15.2) & NDK 14, both run failed with same error
• export CC=aarch64-linux-android-clang
• export CXX=aarch64-linux-android-clang++

MXNet version: installed from source:

MXNet commit hash (git rev-parse HEAD):8a4221bca2ddd4fa05840f7951a7216775021237

Error Message:

When try to run on device, following exception was thrown.

Caused by: java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_ZTVN4dmlc2io23IndexedRecordIOSplitterE" referenced by "/data/app/com.test.face-2/lib/arm64/libmxnet_predict.so"...
                                                                                       at java.lang.Runtime.loadLibrary0(Runtime.java:994)
                                                                                       at java.lang.System.loadLibrary(System.java:1533)
                                                                                       at org.dmlc.mxnet.Predictor.<clinit>(Predictor.java:28)

What have you tried to solve it?

1. with c++fit it shows as below:

% c++filt _ZTVN4dmlc2io23IndexedRecordIOSplitterE
vtable for dmlc::io::IndexedRecordIOSplitter

Want to know if anybody have succeeded in building the arm64 arch for android with latest source. Thanks in advance.

[piiswrong]

@larroy

[zhenglaizhang]

And i checked the so, the symbol is indeeded undefined:

% nm libmxnet_predict.so | grep _ZTVN4dmlc2io23IndexedRecordIOSplitterE
         U _ZTVN4dmlc2io23IndexedRecordIOSplitterE

[larroy]

Please have a look at this PR:
#7792

I added an Android arm64 build file:

Dockerfile.build.android.arm64

I think we should remove the amalgamation and rely on the build system for cross platform builds as we discussed before.

@zhenglaizhang can you provide more details on how are you running on the device?

[zhenglaizhang]

@larroy thanks for quick response!

just with following code at android side.

static {
        System.loadLibrary("mxnet_predict");
    }

Now as i checked, it's all because the generated mxnet_predict-all.cc really misses some method definitions, it compiles but fails at runtime, as I added the missed definitions, 3 to 4 missed definitions, I could load the mxnet_predict so on android device successfully.

Agree with you, amalgamation might be out of dated, and cross platform builds should be better, I will take some time tomorrow to try your dockerfile android arm64 build, hope it will works.

thanks for your helpful info -:)

[larroy]

@zhenglaizhang can you share the code of the project?

[zhenglaizhang]

@larroy Hi,sorry for late response, thanks for the help, with the help from other thread, #4783 i added missing header files and built the so successfully.
And I tried the cross build docker, and found the built so was so large, around 30M if i remember correctly, and I couldn't run that successfully on android device.

[novioleo]

@zhenglaizhang you have to also add indexedRecordIOSplitter into mxnet_predict0.cc

[zhenglaizhang]

@novioleo yeah, you are right, that's what i did to solve the problem. thanks for the info -:)

[novioleo]

@zhenglaizhang i think this issue had been solved,can you close it?

[zhenglaizhang]

Close as the issue was resolved, thanks all for the help!