[GR-29375] Fix disposeThread() ran from a foreign thread and add test

Author: eregon

src/main/java/org/truffleruby/core/fiber/FiberManager.java

@@ -331,7 +331,7 @@ public void killOtherFibers() {
         context.getThreadManager().leaveAndEnter(truffleContext, null, () -> {
             doKillOtherFibers();
             return BlockingAction.SUCCESS;
-        }, true);
+        }, context.getThreadManager().isRubyManagedThread(Thread.currentThread()));
     }
 
     private void doKillOtherFibers() {

src/main/java/org/truffleruby/debug/TruffleDebugNodes.java

@@ -55,6 +55,7 @@
 import org.truffleruby.core.rope.CodeRange;
 import org.truffleruby.core.string.RubyString;
 import org.truffleruby.core.string.StringNodes.MakeStringNode;
+import org.truffleruby.core.thread.ThreadManager;
 import org.truffleruby.extra.ffi.Pointer;
 import org.truffleruby.interop.BoxedValue;
 import org.truffleruby.interop.ToJavaStringNode;
@@ -1002,4 +1003,15 @@ protected RubyString parseName(InternalMethod method) {
 
     }
 
+    /** Creates a Truffle thread that is no {@link ThreadManager#isRubyManagedThread(java.lang.Thread)}}. */
+    @CoreMethod(names = "create_polyglot_thread", onSingleton = true, required = 1)
+    public abstract static class CreatePolyglotThread extends CoreMethodArrayArgumentsNode {
+        @Specialization
+        protected Object parseName(Object hostRunnable) {
+            Runnable runnable = (Runnable) getContext().getEnv().asHostObject(hostRunnable);
+            final Thread thread = getContext().getEnv().createThread(runnable);
+            return getContext().getEnv().asGuestValue(thread);
+        }
+    }
+
 }

src/test/java/org/truffleruby/MiscTest.java

@@ -10,6 +10,7 @@
 package org.truffleruby;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertTrue;
 
@@ -120,6 +121,40 @@ public void testIntegratorThreadRubyThreadInitialization() throws Throwable {
         }
     }
 
+    @Test
+    public void testForeignThread() throws Throwable {
+        // Tests thread initialization and finalization for a foreign thread and an embedder thread
+        try (Context context = Context.newBuilder("ruby").allowCreateThread(true).build()) {
+            context.eval("ruby", "$queue = Queue.new");
+            assertEquals(context.eval("ruby", "Thread.main"), context.eval("ruby", "Thread.current"));
+            assertTrue(context.eval("ruby", "Thread.current").toString().contains("@main"));
+            assertFalse(context.eval("ruby", "Thread.current").toString().contains("<foreign thread>"));
+
+            Runnable polyglotThreadBody = () -> {
+                context.eval("ruby", "$queue.pop");
+                assertTrue(context.eval("ruby", "Thread.current").toString().contains("<foreign thread>"));
+            };
+            Thread polyglotThread = context
+                    .eval("ruby", "Truffle::Debug")
+                    .invokeMember("create_polyglot_thread", polyglotThreadBody)
+                    .asHostObject();
+
+            TestingThread embedderThread = new TestingThread(() -> {
+                context.eval("ruby", "$queue.pop");
+                assertTrue(context.eval("ruby", "Thread.current").toString().contains("<foreign thread>"));
+            });
+
+            polyglotThread.start();
+            embedderThread.start();
+
+            context.eval("ruby", "$queue << 1");
+            context.eval("ruby", "$queue << 2");
+
+            polyglotThread.join(); // causes disposeThread(polyglotThread) to run on polyglotThread
+            embedderThread.join();
+        }
+    }
+
     @Ignore // TODO (eregon, 8 April 2020): not yet working
     @Test
     public void testIntegratorThreadContextClosedOnOtherThread() throws Throwable {