[GR-78917] Use reference queue signal thread.

graalpython/com.oracle.graal.python.test/src/com/oracle/graal/python/test/builtin/objects/cext/ReferenceQueueCoordinatorTests.java

@@ -0,0 +1,195 @@
+/*
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * The Universal Permissive License (UPL), Version 1.0
+ *
+ * Subject to the condition set forth below, permission is hereby granted to any
+ * person obtaining a copy of this software, associated documentation and/or
+ * data (collectively the "Software"), free of charge and under any and all
+ * copyright rights in the Software, and any and all patent rights owned or
+ * freely licensable by each licensor hereunder covering either (i) the
+ * unmodified Software as contributed to or provided by such licensor, or (ii)
+ * the Larger Works (as defined below), to deal in both
+ *
+ * (a) the Software, and
+ *
+ * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
+ * one is included with the Software each a "Larger Work" to which the Software
+ * is contributed by such licensors),
+ *
+ * without restriction, including without limitation the rights to copy, create
+ * derivative works of, display, perform, and distribute the Software and make,
+ * use, sell, offer for sale, import, export, have made, and have sold the
+ * Software and the Larger Work(s), and to sublicense the foregoing rights on
+ * either these or other terms.
+ *
+ * This license is subject to the following condition:
+ *
+ * The above copyright notice and either this complete permission notice or at a
+ * minimum a reference to the UPL must be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.oracle.graal.python.test.builtin.objects.cext;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.junit.Test;
+
+import com.oracle.graal.python.builtins.objects.cext.capi.transitions.ReferenceQueueCoordinator;
+
+public class ReferenceQueueCoordinatorTests {
+
+    @Test
+    public void watcherHandsOffExactlyOneReference() {
+        ReferenceQueueCoordinator coordinator = startedCoordinator();
+        Reference<?> reference = new WeakReference<>(new Object());
+
+        assertTrue(coordinator.beginWatcherRemove());
+        Reference<?> handoff = coordinator.endWatcherRemove(reference);
+
+        assertSame(reference, coordinator.beginWatcherDrain(handoff));
+        coordinator.finishDrain();
+
+        assertTrue(coordinator.beginWatcherRemove());
+        assertNull(coordinator.endWatcherRemove(null));
+        stop(coordinator);
+    }
+
+    @Test
+    public void deferredWatcherDrainRetainsHandoff() {
+        ReferenceQueueCoordinator coordinator = startedCoordinator();
+        Reference<?> reference = new WeakReference<>(new Object());
+
+        assertTrue(coordinator.beginWatcherRemove());
+        Reference<?> handoff = coordinator.endWatcherRemove(reference);
+
+        // A caller that cannot drain yet must be able to leave the handoff pending and retry later.
+        assertSame(reference, coordinator.getPendingReference());
+        assertSame(reference, coordinator.beginWatcherDrain(handoff));
+        coordinator.finishDrain();
+        stop(coordinator);
+    }
+
+    @Test
+    public void forcedDrainSupersedesQueuedHandoff() {
+        ReferenceQueueCoordinator coordinator = startedCoordinator();
+        Reference<?> reference = new WeakReference<>(new Object());
+
+        assertTrue(coordinator.beginWatcherRemove());
+        Reference<?> handoff = coordinator.endWatcherRemove(reference);
+
+        assertSame(reference, coordinator.beginForcedDrain(null));
+        assertNull(coordinator.beginWatcherDrain(handoff));
+        coordinator.finishDrain();
+        stop(coordinator);
+    }
+
+    @Test
+    public void forcedDrainWithoutHandoffIsStillAcquired() {
+        ReferenceQueueCoordinator coordinator = startedCoordinator();
+
+        assertNotNull(coordinator.beginForcedDrain(null));
+        coordinator.finishDrain();
+        stop(coordinator);
+    }
+
+    @Test
+    public void disabledCoordinatorPreservesHandoffUntilReenabled() {
+        ReferenceQueueCoordinator coordinator = startedCoordinator();
+        Reference<?> reference = new WeakReference<>(new Object());
+
+        assertTrue(coordinator.beginWatcherRemove());
+        Reference<?> handoff = coordinator.endWatcherRemove(reference);
+
+        assertTrue(coordinator.disable(null));
+        assertNull(coordinator.beginWatcherDrain(handoff));
+        assertNull(coordinator.beginForcedDrain(null));
+
+        coordinator.enable();
+        assertSame(reference, coordinator.beginWatcherDrain(handoff));
+        coordinator.finishDrain();
+        stop(coordinator);
+    }
+
+    @Test
+    public void disabledCoordinatorResumesWatcherWhenReenabled() {
+        ReferenceQueueCoordinator coordinator = startedCoordinator();
+
+        assertTrue(coordinator.disable(null));
+        coordinator.enable();
+        assertTrue(coordinator.beginWatcherRemove());
+        assertNull(coordinator.endWatcherRemove(null));
+        stop(coordinator);
+    }
+
+    @Test
+    public void stopInvalidatesPendingHandoff() {
+        ReferenceQueueCoordinator coordinator = startedCoordinator();
+        Reference<?> reference = new WeakReference<>(new Object());
+
+        assertTrue(coordinator.beginWatcherRemove());
+        Reference<?> handoff = coordinator.endWatcherRemove(reference);
+        coordinator.stop();
+
+        assertFalse(coordinator.isActive());
+        assertNull(coordinator.beginWatcherDrain(handoff));
+    }
+
+    @Test
+    public void blockingRemoveIsInterruptibleForStop() throws InterruptedException {
+        ReferenceQueueCoordinator coordinator = new ReferenceQueueCoordinator();
+        ReferenceQueue<Object> queue = new ReferenceQueue<>();
+        CountDownLatch removing = new CountDownLatch(1);
+        AtomicReference<Reference<?>> result = new AtomicReference<>();
+        Thread watcher = new Thread(() -> {
+            if (coordinator.beginWatcherRemove()) {
+                removing.countDown();
+                Reference<?> reference = coordinator.blockingRemove(queue);
+                result.set(reference);
+                coordinator.endWatcherRemove(reference);
+            }
+            coordinator.stopped();
+        });
+        coordinator.start(watcher);
+
+        assertTrue(removing.await(1, TimeUnit.SECONDS));
+        coordinator.stop();
+
+        assertFalse(watcher.isAlive());
+        assertNull(result.get());
+        assertFalse(coordinator.isActive());
+    }
+
+    private static ReferenceQueueCoordinator startedCoordinator() {
+        ReferenceQueueCoordinator coordinator = new ReferenceQueueCoordinator();
+        coordinator.start(new Thread(() -> {
+        }));
+        assertTrue(coordinator.isActive());
+        return coordinator;
+    }
+
+    private static void stop(ReferenceQueueCoordinator coordinator) {
+        coordinator.stop();
+        assertFalse(coordinator.isActive());
+    }
+}

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/PythonLanguage.java

@@ -433,6 +433,14 @@ protected void finalizeContext(PythonContext context) {
         boundaryCallDataMap.size();
     }
 
+    @Override
+    protected void disposeContext(PythonContext context) {
+        if (context.getCApiContext() != null) {
+            context.getCApiContext().dispose();
+        }
+        super.disposeContext(context);
+    }
+
     @Override
     protected boolean areOptionsCompatible(OptionValues firstOptions, OptionValues newOptions) {
         return PythonOptions.areOptionsCompatible(firstOptions, newOptions);

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/GcModuleBuiltins.java

@@ -211,7 +211,7 @@ static long javaCollect(Node inliningTarget, GilNode gil) {
             }
             // collect some weak references now
             PythonContext.triggerAsyncActions(inliningTarget);
-            CApiTransitions.pollReferenceQueue();
+            CApiTransitions.pollReferenceQueueIfPending(PythonContext.get(null));
             /*
              * CPython's GC returns the number of collected cycles. This is not something we can
              * determine, but to return some useful info to the Python program, we return the amount

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/cext/PythonCextBuiltins.java

@@ -698,7 +698,7 @@ public Object execute(Object[] arguments) {
                     if (retNode != null) {
                         result = retNode.execute(result);
                     }
-                    CApiTransitions.maybeGCALot();
+                    CApiTransitions.maybeGCALot(this);
                     return result;
                 } catch (Throwable t) {
                     throw checkThrowableBeforeNative(t, "CApiBuiltin", self.name);
@@ -1044,7 +1044,7 @@ static void GraalPyPrivate_TriggerGC(long delay) {
             // Restore interrupt status
             Thread.currentThread().interrupt();
         }
-        CApiTransitions.pollReferenceQueue();
+        CApiTransitions.pollReferenceQueueIfPending(PythonContext.get(null));
         PythonContext.triggerAsyncActions(EncapsulatingNodeReference.getCurrent().get());
     }