UnsatisfiedLinkError with Amalgamation for Android

[dmazzoni]

Description

I have compiled libmxpredict.so for Android following the guide found at #7146, but loading it inside an app causes a java.lang.UnsatisfiedLinkError at runtime.

Environment info

Operating System: macOS 10.13.1
NDK version: android-ndk-r14b
Compiler: arm-linux-androideabi-clang++
MXNet version: v0.12.0
MXNet commit hash : * 0.12.0 4f2af2d

Error message

Process: com.happen.it.make.whatsthis, PID: 29304
java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_ZN4dmlc2io10FileSystem22ListDirectoryRecursiveERKNS0_3URIEPNSt6__ndk16vectorINS0_8FileInfoENS5_9allocatorIS7_EEEE" referenced by "/data/app/com.happen.it.make.whatsthis-2/lib/arm/libmxnet_predict.so"...
at java.lang.Runtime.loadLibrary(Runtime.java:372)
at java.lang.System.loadLibrary(System.java:1076)
at org.dmlc.mxnet.Predictor.<clinit>(Predictor.java:5)
at com.happen.it.make.whatisit.WhatsApplication.onCreate(WhatsApplication.java:48)
at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1013)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4707)
at android.app.ActivityThread.-wrap1(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1405)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Minimum reproducible example

I am compiling the WhatsThis sample app from my repo (https://github.com/dmazzoni/WhatsThis.git) with Android Studio 3.0, and running it on a Nexus 5 with Android 6.0.1. The repository includes the libmx_predict.so I recompiled, together with libopenblas.so and libc++_shared.so, whose absence caused linker errors, now solved.

Steps to reproduce

1. Compile and run the Android application.

[dmazzoni]

Solved by adding the line #include "../dmlc-core/src/io/filesys.cc" to dmlc-minimum0.cc

[bryanlinnan]

hi，i followed your method, add the line to dmlc-minimum0.cc and recompile another libmxnet_predict.so, still got the error: "can not locate symbol _ZN4dmlc2io10FileSystem22ListDirectoryRecursiveERKNS0_3URIEPNSt6__ndk16vectorINS0_8FileInfoENS5_9allocatorIS7_EEEE" referenced by "/data/app/com.happen.it.make.whatsthis-2/lib/arm/libmxnet_predict.so"." is there any other step you did?