Issue building android-demo

[nicholas-leonard]

Hi soumith,

So I was able to build using the first build.sh. Then I manually copied the static .a libs to the lib folder. But then when I get to compiling the android-demo using that build.sh, I get the following error:

nicholas14@hermes:~/projects/torch-android/android-demo$ bash build.sh 
Updated local.properties
Updated file ./proguard-project.txt
Android NDK: WARNING: APP_PLATFORM android-17 is larger than android:minSdkVersion 14 in ./AndroidManifest.xml    
Android NDK: WARNING:jni/Android.mk:torchdemo: non-system libraries in linker flags: -lgomp -lluaT -ltorch-lua-static -lTH -lnn -ltorch -lnnx -limage -limgraph -lluaT -ltorch-lua-static -lTH -lnn -ltorch -lnnx -limage -limgraph    
Android NDK:     This is likely to result in incorrect builds. Try using LOCAL_STATIC_LIBRARIES    
Android NDK:     or LOCAL_SHARED_LIBRARIES instead to list the library dependencies of the    
Android NDK:     current module    
[armeabi-v7a] Compile++ thumb: torchdemo <= torchandroid.cpp
[armeabi-v7a] Compile++ thumb: torchdemo <= torchdemo.cpp
[armeabi-v7a] Compile thumb  : torchdemo <= android_fopen.c
[armeabi-v7a] SharedLibrary  : libtorchdemo.so
../lib//libnn.a(init.c.o):init.c:function nn_FloatSqrt_updateGradInput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatSquare_updateGradInput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatSquare_updateOutput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatHardTanh_updateGradInput: error: undefined reference to 'GOMP_parallel'
collect2: error: ld returned 1 exit status

[soumith]

I dont have computer access today, will look into it tomorrow. It has to just be linked against openmp with the compiler flag -fopenmp

[nicholas-leonard]

Yeah the -fopenmp is part of the build command, but still doesn't work:

/home/nicholas14/Downloads/android-ndk-r10d/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++ -Wl,-soname,libtorchdemo.so -shared --sysroot=/home/nicholas14/Downloads/android-ndk-r10d/platforms/android-17/arch-arm ./obj/local/armeabi-v7a/objs/torchdemo/torchandroid.o ./obj/local/armeabi-v7a/objs/torchdemo/torchdemo.o ./obj/local/armeabi-v7a/objs/torchdemo/android_fopen.o /home/nicholas14/Downloads/android-ndk-r10d/sources/cxx-stl/gnu-libstdc++/4.8/libs/armeabi-v7a/thumb/libgnustl_static.a -lgcc -no-canonical-prefixes -march=armv7-a -Wl,--fix-cortex-a8  -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -mthumb -fopenmp -L/home/nicholas14/Downloads/android-ndk-r10d/platforms/android-17/arch-arm/usr/lib -llog -landroid -L../lib/ -lgomp -lluaT -ltorch-lua-static -lTH -lnn -ltorch -lnnx -limage -limgraph -lluaT -ltorch-lua-static -lTH -lnn -ltorch -lnnx -limage -limgraph -lc -lm -lgomp -o ./obj/local/armeabi-v7a/libtorchdemo.so 
../lib//libnn.a(init.c.o):init.c:function nn_FloatSqrt_updateGradInput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatSquare_updateGradInput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatSquare_updateOutput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatHardTanh_updateGradInput: error: undefined reference to 'GOMP_parallel'
collect2: error: ld returned 1 exit status

[nicholas-leonard]

Which is related to all these lines in the c code of nn's prebuilt static library:

#pragma omp parallel for private(k)

[nicholas-leonard]

Error happens on both ubuntu 12.04 and 14.04.

[nicholas-leonard]

Ok so I was able to build the android-demo but only after disabling OPENMP compilation from torch and nnx. I don't want to submit a PR for my changes because I believe there should be a way to compile the torch and nnx static libraries with the same OpenMP libraries used by the new ndk versions that support it.

[jgemmeke]

EDIT: Seems I was mistaken: it is simply a linking problem. For some reason the libgomp in the toolchain is not linked during compilation. Copying it from the android toolchain subdirs to ../lib worked for me, adding -lgomp did not.

But I don't know enough about android app compilation to come up with the proper fix.

That said:

• the camera-dependent apps still don't work for me - I get errors about preview sizes not being supported. Only the barebones torchdemo app works
• I cannot get the neon version build - I get assembly compilation errors (which usually indicate that the neon compile flags are not set, but the cmak scripts do seem to set them)

[soumith]

@jgemmeke NEON might not compile on armv8, there's some armv7 specific assembly there (wish that my work at @museami would be open-sourced, I rewrote all of it and a faster version for v8 as well).

the camera preview-sizes error is an android thing. you must be using some non-standard camera, we wrote these demos targeting most standard phones.

[rio0286]

For your information,
I got same library copy problem as other issue after updating android.toolchain.cmake for ndk version r10, a month ago.
So I manually copied libraries for testing but it does not work with this demo build error.
I found that some function like __srget removed after ndk version r10.
I think these functions are used in torch code and I cannot fix it.
So I rollbacked android.toolchain.cmake to r9.

you can find this information in this page with click on Android NDK, Revision 10c (October 2014)
https://developer.android.com/tools/sdk/ndk/index.html

[rio0286]

@jgemmeke you can fix that camera-dependent app error with removing some lines in demo code.

CameraClass.jave 65th line parameters.setPreviewSize(1280, 768);

After commenting this line, preview size remains as your phone's default configuration and it may work.
but the recognition result may not good.

I think that will be nice if there are some resizing step instead of using fixed preview size(1280,768)

[nicholas-leonard]

@jgemmeke Tried dropping the static libgomp.a and linking it during the compilation of the android demo, but still get the same errors. What am I missing?

My Android.mk file:

LOCAL_PATH := $(call my-dir)

LOCAL_CFLAGS += -fopenmp
LOCAL_LDFLAGS += -fopenmp

LOCAL_EXPORT_C_INCLUDES := $(TORCH_ANDROID)/include/torch
LOCAL_MODULE := gomp
LOCAL_SRC_FILES := /home/nicholas14/Downloads/android-ndk-r10d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/arm-linux-androideabi/lib/libgomp.a
include $(PREBUILT_STATIC_LIBRARY)
LOCAL_STATIC_LIBRARIES += gomp

LOCAL_MODULE := torch-lua-static
LOCAL_SRC_FILES := $(TORCH_ANDROID)/lib/libtorch-lua-static.a
include $(PREBUILT_STATIC_LIBRARY)

LOCAL_MODULE := luaT
LOCAL_SRC_FILES := $(TORCH_ANDROID)/lib/libluaT.a
LOCAL_STATIC_LIBRARIES += torch-lua-static
include $(PREBUILT_STATIC_LIBRARY)

LOCAL_MODULE := TH
LOCAL_SRC_FILES := $(TORCH_ANDROID)/lib/libTH.a
LOCAL_STATIC_LIBRARIES += luaT
include $(PREBUILT_STATIC_LIBRARY)

LOCAL_MODULE := torch
LOCAL_SRC_FILES := $(TORCH_ANDROID)/lib/libtorch.a
LOCAL_STATIC_LIBRARIES += TH
include $(PREBUILT_STATIC_LIBRARY)

LOCAL_MODULE := nn
LOCAL_SRC_FILES := $(TORCH_ANDROID)/lib/libnn.a
LOCAL_STATIC_LIBRARIES += torch
include $(PREBUILT_STATIC_LIBRARY)

LOCAL_MODULE := nnx
LOCAL_SRC_FILES := $(TORCH_ANDROID)/lib/libnnx.a
LOCAL_STATIC_LIBRARIES += nn
include $(PREBUILT_STATIC_LIBRARY)

LOCAL_MODULE := image
LOCAL_SRC_FILES := $(TORCH_ANDROID)/lib/libimage.a
LOCAL_STATIC_LIBRARIES += nnx
include $(PREBUILT_STATIC_LIBRARY)

LOCAL_MODULE := imgraph
LOCAL_SRC_FILES := $(TORCH_ANDROID)/lib/libimgraph.a
LOCAL_STATIC_LIBRARIES += image
include $(PREBUILT_STATIC_LIBRARY)

LOCAL_STATIC_LIBRARIES += imgraph
LOCAL_MODULE := torchdemo
LOCAL_C_INCLUDES += $(TORCH_ANDROID)/include/torch
LOCAL_SRC_FILES := torchandroid.cpp torchdemo.cpp android_fopen.c
LOCAL_LDLIBS := -llog -landroid
include $(BUILD_SHARED_LIBRARY)

[nicholas-leonard]

I made a little test to see if I could compile a part of the android-demo with openmp support. In torchandroid.cpp, I added:

#include <omp.h>
...
lua_State* inittorch(AAssetManager* manager) {
...
  char buffer[4096]; // buffer for textview output
#pragma omp parallel for
    for(int i = 0;i < 100;i++) {
        /* Do work... */
        buffer[i] = 'd';
    }
  return L;
}

It compiled with the build command issued by ndk-build:

/home/nicholas14/Downloads/android-ndk-r10d/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++ -MMD -MP -MF ./obj/local/armeabi-v7a/objs/torchdemo/torchandroid.o.d -fpic -ffunction-sections -funwind-tables -fstack-protector -no-canonical-prefixes -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=softfp -fno-exceptions -fno-rtti -mthumb -Os -g -DNDEBUG -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64 -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/projects/torch-android//include/torch -I/home/nicholas14/Downloads/android-ndk-r10d/sources/cxx-stl/gnu-libstdc++/4.8/include -I/home/nicholas14/Downloads/android-ndk-r10d/sources/cxx-stl/gnu-libstdc++/4.8/libs/armeabi-v7a/include -I/home/nicholas14/Downloads/android-ndk-r10d/sources/cxx-stl/gnu-libstdc++/4.8/include/backward -Ijni -DANDROID -fopenmp -Wa,--noexecstack -Wformat -Werror=format-security   -fopenmp   -I/home/nicholas14/Downloads/android-ndk-r10d/platforms/android-17/arch-arm/usr/include -c  jni/torchandroid.cpp -o ./obj/local/armeabi-v7a/objs/torchdemo/torchandroid.o

So that would seem to indicate that the issue lies in how we compile torch-android, and not the android-demo...

[jgemmeke]

Literally the only thing I need to do to get the demos compiled (just tested with fresh git clone of the repo)

cp ~/android-ndk-r10d/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/lib/libgomp.a lib/

I welcome understanding why this works for me, and what the proper way to do it is :)

[jgemmeke]

Forgot (to mention) I overwrote my libgomp files with the ones posted in the comments in this thread:

http://recursify.com/blog/2013/08/09/openmp-on-android-tls-workaround

Which probably makes the difference.

[nicholas-leonard]

Yeah also tried that. It works for me now thanks to your comment. Actually reverted to the old style Android.mk as the one I posted above, although it fixes an ndk-build warning, sucks. Tomorrow will try to compile on my buddy's computer to confirm what steps are actually necessary. I also made some changes to the torch-android build.sh.

[nicholas-leonard]

The key was in fact changing the cmake command in the torch-android build.sh to:

cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/android.toolchain.cmake .. -DCMAKE_INSTALL_PREFIX=$INSTALL_DIR -DANDROID_STL=none -DCMAKE_BUILD_TYPE=Release -DANDROID_TOOLCHAIN_NAME=arm-linux-androideabi-4.8 -DANDROID_NO_UNDEFINED=ON

No need to drop the libgomp.a.
No need to do any of the recursify stuff.

[soumith]

oh! nice. can you PR? let me just add you to the repo

[alfo888]

hi @nicholas-leonard , i get the same error. After build using sh build.sh in torch-android-master i copy manually the libraries ( found using in the shell "$find . -name *.a") inside the folder /torch-android-master/lib.

I enter in android-demo folder and launching "$sh build.sh" (or using ndk-build comand after adding ndk-build at the enviroment varibles) I get:

alfonso@alfonso-Precision-T1700:~/AndroidStudioProjects/torch-android-master/android-demo$ sh build.sh
Picked up JAVA_TOOL_OPTIONS: -javaagent:/usr/share/java/jayatanaag.jar
Picked up JAVA_TOOL_OPTIONS: -javaagent:/usr/share/java/jayatanaag.jar
Picked up JAVA_TOOL_OPTIONS: -javaagent:/usr/share/java/jayatanaag.jar
Updated local.properties
Updated file ./proguard-project.txt
Android NDK: WARNING: APP_PLATFORM android-17 is larger than android:minSdkVersion 14 in ./AndroidManifest.xml
Android NDK: WARNING:jni/Android.mk:torchdemo: non-system libraries in linker flags: -lluaT -ltorch-lua-static -lTH -lnn -ltorch -lnnx -limage -limgraph -lluaT -ltorch-lua-static -lTH -lnn -ltorch -lnnx -limage -limgraph
Android NDK: This is likely to result in incorrect builds. Try using LOCAL_STATIC_LIBRARIES
Android NDK: or LOCAL_SHARED_LIBRARIES instead to list the library dependencies of the
Android NDK: current module
[armeabi-v7a] Compile++ thumb: torchdemo <= torchandroid.cpp
[armeabi-v7a] Compile++ thumb: torchdemo <= torchdemo.cpp
In file included from jni/torchdemo.cpp:8:0:
jni/torchdemo.cpp: In function 'jstring* Java_com_torch_torchdemo_TorchDemo_callTorch(JNIEnv, jobject, jobject)':
jni/torchandroid.h:19:78: warning: too many arguments for format [-Wformat-extra-args]

define D(x...) __android_log_print(ANDROID_LOG_INFO,"torchdemo", "%s", x)

                                                                          ^

jni/torchdemo.cpp:35:7: note: in expansion of macro 'D'
D("Error doing resource: %s\n", file);
^
[armeabi-v7a] Compile thumb : torchdemo <= android_fopen.c
[armeabi-v7a] SharedLibrary : libtorchdemo.so
../lib//libnn.a(init.c.o):init.c:function nn_FloatSqrt_updateGradInput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatSquare_updateGradInput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatSquare_updateOutput: error: undefined reference to 'GOMP_parallel'
../lib//libnn.a(init.c.o):init.c:function nn_FloatHardTanh_updateGradInput: error: undefined reference to 'GOMP_parallel'
collect2: error: ld returned 1 exit status
make: *_* [obj/local/armeabi-v7a/libtorchdemo.so] Error 1

I tried to change the cmake command in the torch-android build.sh to:

cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/android.toolchain.cmake .. -DCMAKE_INSTALL_PREFIX=$INSTALL_DIR -DANDROID_STL=none -DCMAKE_BUILD_TYPE=Release -DANDROID_TOOLCHAIN_NAME=arm-linux-androideabi-4.8 -DANDROID_NO_UNDEFINED=ON

I am usuing ubuntu 15.04 64bit

Thanks in advance

[nicholas-leonard]

@alfo888 Haven't touched this in a while. You might want to try a different NDK version. gcc/g++ 4.9 might also do the trick. The solution seems to be different for every OS.