UnsatisfiedLinkError with native library under sbt

Question

I'm using sbt 0.13 and have issues using the leveldbjni native library under sbt (even after issue #358 has been resolved). A similar issue has already been reported for which sbt 0.13 should provide a solution but it seems it doesn't. So I'm sharing my observations here.

I'm getting an UnsatisfiedLinkError with the following example application.

• build.sbt

  name := "example"
  
  version := "0.1"
  
  scalaVersion := "2.10.2"
  
  libraryDependencies += "org.fusesource.leveldbjni" % "leveldbjni-all" % "1.7"
  

• build.properties

   sbt.version=0.13.0
  

• Example.scala

  import org.fusesource.leveldbjni.internal._
  
  object Example extends App {
    NativeDB.LIBRARY.load() // loading succeeds 
    new NativeOptions() // UnsatisfiedLinkError under sbt
  }
  

I'm using Oracle JDK 1.7 and OS X 10.8.5. Running the example with run-main Example under sbt gives

[error] (run-main) java.lang.UnsatisfiedLinkError: org.fusesource.leveldbjni.internal.NativeOptions.init()V

whereas running it with

java -cp scala-library.jar:example_2.10-0.1.jar:leveldbjni-all-1.7.jar Example

just works fine. The application even runs successfully when Scala is on the bootclasspath:

java -Xbootclasspath/a:scala-library.jar -cp example_2.10-0.1.jar:leveldbjni-all-1.7.jar Example

Any ideas why there's an UnsatisfiedLinkError only under sbt?

Answer 1

Any ideas why there's an UnsatisfiedLinkError only under sbt?

As @juereth commented:

Sbt is using magic classloaders to try to prevent "leaks" of native loaded libraries, and allow you to re-import the library multiple times. Sbt will actually rename the DLL/SO/jnilib and load it in a special classloader. I'm not positive if this is only a plugin feature, or something for all apps.

So this is somewhat expected behavior with the current design of sbt. If forking works, then that's what you have to do.