Fix race condition of loadedLibraries

[louxiu]

We should put lib to loadedLibraries only after System.load(lib)
success, or loadedLibraries.get(lib) will get it in other thread
before we remove it after System.load(lib) failed.

[saudet]

The reason we can't do that is because System.load() calls JNI_OnLoad(), which might start loading other classes that may include the class we're already trying to load, as part of some cycle. We need a way to detect that we're already loading a given class. What issues are you encountering with the current scheme?

[saudet]

I see, a race condition could occur in there if we're not loading from a static { } block or something. Those are basically synchronized, maybe we should make Loader.loadLibrary() synchronized as well?

[louxiu]

Another confusion about this line. platform.link is

A list of libraries the native compiler should link with

Why it is necessary to try to load them when we run the application(static {Loader.load();})?

[saudet]

When we link against shared libraries, yes, we need to try to load them. But we can disable that behavior by suffixing them with #, which is used to rename library files on load, but if no name is given, they just don't get loaded.