Realm-java: Build realm-java under windows

[Drjacky]

I'm going to build realm. So run this command in command prompt:

gradlew assemble

But I got this error:

* What went wrong:
Execution failed for task ':realm-library:downloadCore'.
> Java heap space

Windows 7 64-bit Ultimate
Gradle 3.1
cygwin 2.5.2 64bit
Installed JDKs and JREs:
64bit:

jdk1.8.0_121
jre1.8.0_121

32bit:

jdk1.8.0_121
jre1.8.0_121
jdk1.7.0_80
jre7
jdk1.6.0_45
jre6

Used java version in Environment Variables: 1.8.0_121

[Zhuinden]

Well it claims it ran out of memory, you can try adding more memory if you have a build.gradle where you can put this:

dexOptions{
    javaMaxHeapSize "4g"
}

Although considering this is not dex, i'm not sure if it helps

[Drjacky]

@Zhuinden I tested this before, and didn't help.
Even change

org.gradle.jvmargs=-XX:MaxPermSize=512m

From

\realm\realm-java\gradle.properties

To something more
Or change

org.gradle.jvmargs=-Xms512m -Xmx2048m

From

\realm\realm-java\realm\gradle.properties

To something more
Or
Put gradle.properties under

\realm\realm-java\realm

With this content:

org.gradle.jvmargs=-Xms2048m -Xmx4048m

Didn't help.
But when I set

GRADLE_OPTS=-Xmx2048m

In Environment Variables, I get this error:

Could not reserve enough space for 2097152

[Zhuinden]

Make sure you close Chrome and other memory intensive stuff for this process to work

[kneth]

From the screenshot I assume that you are using Windows. We have tried to build under Windows so I can't tell if it's a Windows issue or not. Moreover, building Realm requires Android NDK which in the past wasn't working that well under Windows. My recommendation is that you install Linux in a virtual machine and try to build using that.

Switch to Windows 10 and use the built-in Linux support might be another option. Again, we haven't tried that.

[Drjacky]

@Zhuinden I have 32GB memory on my machine; And about 20GB is free. @kneth I'll try these solution too...

[kneth]

Can it be that you are using the 32 bit version of the JVM? The number reported indicated that you are not allowed to allocate more than 2 GB.

[kneth]

Btw, building Realm Java requires NDK r10e. Previously the NDK had issues on Windows: https://github.com/android-ndk/ndk/issues/139

[Drjacky]

@kneth Memory heap problem caused by JDK 32bit. I changed it to JDK 64bit and I get this error now:

I downloaded CMake from Android Studio.

[beeender]

It could be the same problem with https://github.com/taka-no-me/android-cmake/issues/94

@Drjacky would you please try to modify the ./realm/realm-library/src/main/cpp/android.toolchain.cmake as it is described here and let us know the results? I don't have a windows machine right now so i cannot verify it :(
Thanks!

[Drjacky]

@beeender After those changes: I got this:

[beeender]

@Drjacky Make sure the javah is in your system's PATH so cmake can find it to generate jni header files from java class.

[Drjacky]

@beeender It's exist!

[beeender]

hmmm, maybe it is trying to find the javah by JAVA_HOME. Can you try to set the JAVA_HOME to your JDK home?

[Drjacky]

@beeender This is my whole Environment Variables:

[beeender]

Does C:\Program Files\Java\jdk1.8.0_121\bin\javah.exe exist?

[Drjacky]

@beeender Yes.

[beeender]

It is very strange. Probably caused by the cmake doesn't play well with windows path separator.
So maybe you can try to handcode the javah path in ./realm/realm-library/src/main/cpp/android.toolchain.cmake. Before line 10 else(), something like:

    elseif (EXISTS "C:/Program Files/Java/jdk1.8.0_121/bin/javah.exe")
        set(Java_JAVAH_EXECUTABLE "C:/Program Files/Java/jdk1.8.0_121/bin/javah.exe")

You might need to remove the line 6-7 since you actually have the JAVA_HOME set.

Also, if it doesn't work, try to change the path separator to \\.

[beeender]

or maybe you only need to add .exe to line 6-7

[Drjacky]

@beeender I coudn't find that line. This is my android.toolchain.cmake
*Note: Attaching ZIP file failed. So I changed text file extension to JPG. Please download this file and remove JPG extension.
Link

[beeender]

uh ... Really sorry, I put a wrong file path there. It should be ./realm/realm-library/src/main/cpp/CMakeLists.txt

[Drjacky]

@beeender Adding .exe to javah didn't help. But when I added another elseif, javah not found error gone, but this error:

[beeender]

It might be a cmake bug which is similar to https://llvm.org/bugs/show_bug.cgi?id=27226 ...
I don't have immediate idea right now ... I suggest you to try compile it under linux (virtual machine maybe?) or maybe you can try with build it in cygwin? It might solve it but i am not sure.

I will mark this as an low priority issue. And it will not be solved soon since no one is using windows in the team. Sorry :(

[cmelchior]

Folding this into the original issue about Windows support: #911