On 26/02/2017 11:20, Doug Simon wrote:
While trying to get upstream Graal working again with JDK 9, I'm having
problems with service loading. Graal uses a LayoutFactory service defined by
Truffle where the latter also includes a provider. The relevant parts of the
module-info descriptors are:
module com.oracle.truffle.truffle_api {
exports com.oracle.truffle.object;
exports com.oracle.truffle.object.basic;
uses com.oracle.truffle.api.object.LayoutFactory;
provides com.oracle.truffle.api.object.LayoutFactory with
com.oracle.truffle.object.basic.DefaultLayoutFactory;
}
module jdk.internal.vm.compiler {
requires transitive com.oracle.truffle.truffle_api;
uses com.oracle.truffle.api.object.LayoutFactory;
}
However, looking up a provider in Graal[1] returns no providers. As far as I
understand service loading with modules, this is because
jdk.internal.vm.compiler is loaded via the platform class loader while truffle
is loaded via the app class loader as shown by the output of trace statements I
added:
GraalTruffleRuntime.class.getClassLoader() ->
jdk.internal.loader.ClassLoaders$PlatformClassLoader@366e2eef
LayoutFactory.class.getClassLoader() ->
jdk.internal.loader.ClassLoaders$AppClassLoader@6df97b55
This ability of a platform loaded class to depend on an app loaded class is
probably due to the soon-to-be-disabled mechanism[2] we use for overriding the
version of Graal bundled with JDK 9.
Is there some command line magic I can use to make this case work now or do I
have to wait until [2] is addressed? If the latter, how will it work then?
An upgraded moduledefined to the platform loader can link to types in
modules defined to the app loader. So I wouldn't expect issues there.
Can you track down the code that uses ServiceLoader.load to load the
LayoutFactory providers? It might be using loadInstalled or invoking it
with the platform class loader and that would explain what you are seeing.
-Alan
