Kotlin: Getting UnsatisfiedLinkError: no wasmer_jni in java.library.path when creating Instance

[onurhb]

I am getting following exception with simple example as shown in in this introduction post:

Exception in thread "main" java.lang.UnsatisfiedLinkError: no wasmer_jni in java.library.path
	at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1860)
	at java.lang.Runtime.loadLibrary0(Runtime.java:870)
	at java.lang.System.loadLibrary(System.java:1124)
	at org.wasmer.Instance.<clinit>(Instance.java:17)
	at ApplicationKt.main(Application.kt:13)

See following repository: https://github.com/onurhkb/wasm-test

Edit: Using latest version of Intellij

[Hywan]

Hello,

What's your platform? How did you install Wasmer JNI (edit: With Gradle as per your repository)?

Thanks.

[Hywan]

I see you're using Kotlin. I didn't try with Kotlin yet, but I wouldn't be surprise to see differences between Java and Kotlin here.

[onurhb]

Hi, I am on Mac Catalina 10.15.5. Yes, I am using gradle as shown in the example repository. I tried this with Java and got the same problem:

Exception in thread "main" java.lang.UnsatisfiedLinkError: no wasmer_jni in java.library.path: [/Users/<User>/Library/Java/Extensions, /Library/Java/Extensions, /Network/Library/Java/Extensions, /System/Library/Java/Extensions, /usr/lib/java, .]

Did you try Intellij?

[Hywan]

I don't use IntelliJ. I'm not familiar with IntelliJ nor Kotlin. I asked help on Twitter, https://twitter.com/mnt_io/status/1295331545771802625.

[bashor]

AFAIK you need to extract your dynamic library to somewhere (usually to some tmp dir) and load it by calling System.load with a path to the file. You can delegate the task to some library, like:

• https://github.com/adamheinrich/native-utils
• https://github.com/scijava/native-lib-loader
• https://github.com/fusesource/hawtjni

As a workaround, library users could extract a dynamic library themselves and a directory to java.library.path before calling your API.

[Hywan]

The current solution works with Java, but it seems to not work with Kotlin. Is it a difference between the two “languages”?

Our Native API, https://github.com/wasmerio/java-ext-wasm/blob/master/src/java/org/wasmer/Native.java. How to use it, https://github.com/wasmerio/java-ext-wasm/blob/master/src/java/org/wasmer/Instance.java#L15-L19.

Maybe something isn't working with Kotlin 🤔, but what?

[bashor]

Could you please share a simple working example in Java?

[bashor]

Honestly, I don't think it's something specific for Kotlin, likely it will not work in a clean environment for any JVM languages, including Java. It could work for somebody because they have required libraries somewhere where JVM searching because a path is part of java.library.path. If so, an example in other languages should work in the same environment.

[bashor]

You can find a simple example with Kotlin and Java here. Both fail with UnsatisfiedLinkError: no wasmer_jni in java.library.path.

[Arash217]

I’m having the same issue on macOS 10.15.6 (Catalina) with Java 11, when trying to run the examples:

Exception in thread "main" java.lang.UnsatisfiedLinkError: no wasmer_jni in java.library.path: [/Users/<user>/Library/Java/Extensions, /Library/Java/Extensions, /Network/Library/Java/Extensions, /System/Library/Java/Extensions, /usr/lib/java, .]
	at java.base/java.lang.ClassLoader.loadLibrary(ClassLoader.java:2670)
	at java.base/java.lang.Runtime.loadLibrary0(Runtime.java:830)
	at java.base/java.lang.System.loadLibrary(System.java:1873)
	at org.wasmer.Instance.<clinit>(Instance.java:17)
	at SimpleExample.main(SimpleExample.java:10)
make: *** [run-example] Error 1

The examples do work on a Docker container using Debian 10 and Java 11. It seems like it’s OS related.

@bashor what OS did you use for the examples?

[bashor]

@Arash217 I've tried on macOS. How did you run it in Docker?

[Arash217]

@bashor Within the Docker container I cloned the wasmer-java repo, manually installed required packages like Java, Gradle, etc. and then ran the examples using 'make run-example EXAMPLE=[name]'. Make sure you install Java 11, newer versions of Java gave me errors.

[artur-ciocanu]

@bashor after some debugging, I was able to run wasmer-java from IntelliJ on Mac OS X. I had to add:

-Dos.arch=amd64

To VM Options under Run/Debug Configurations for my project.

As far as I can tell there was a recent change that changed wasmer-jni-x86_64-darwin-....jar to wasmer-jni-amd64-darwin-....jar, because of this change during startup the linker can't find the right native lib.

Please let me know if this helps.

[yuer1727]

You can find a simple example with Kotlin and Java here. Both fail with UnsatisfiedLinkError: no wasmer_jni in java.library.path.

yes , i failed in java too.

[yuer1727]

@bashor after some debugging, I was able to run wasmer-java from IntelliJ on Mac OS X. I had to add:

-Dos.arch=amd64

To VM Options under Run/Debug Configurations for my project.

As far as I can tell there was a recent change that changed wasmer-jni-x86_64-darwin-....jar to wasmer-jni-amd64-darwin-....jar, because of this change during startup the linker can't find the right native lib.

Please let me know if this helps.

thanks very much ! it's work.

[yh94]

oh， it's work ,thanks.