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Keep weak references to eager resources in session (#229)
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70 changes: 70 additions & 0 deletions
70
...flow-core/tensorflow-core-api/src/main/java/org/tensorflow/internal/WeakPointerScope.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,70 @@ | ||
| package org.tensorflow.internal; | ||
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| import java.util.Collections; | ||
| import java.util.Set; | ||
| import java.util.WeakHashMap; | ||
| import org.bytedeco.javacpp.Pointer; | ||
|
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| /** | ||
| * A minimalist pointer scope only keeping weak references to its elements. | ||
| * | ||
| * <p>As opposed to {@link org.bytedeco.javacpp.PointerScope}, instances of this class will not | ||
| * prevent the garbage collector to free the memory of a pointer that is no longer reachable, even | ||
| * if it has been attached to the scope.</p> | ||
| * | ||
| * <p>When the scope is closed, all pointers that are still valid will be automatically deallocated | ||
| * while those already garbage-collected will be ignored.</p> | ||
| */ | ||
| public class WeakPointerScope implements AutoCloseable { | ||
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| /** | ||
| * Attach a pointer to this scope. | ||
| * | ||
| * <p>Pointers attached to the scope will be automatically freed once the scope is closed, unless | ||
| * they have been already released by the garbage collector</p> | ||
| * | ||
| * <p>It this {@code pointer} was already attached to this scope, this method has no effect.</p> | ||
| * | ||
| * @param pointer pointer to attach | ||
| * @throws IllegalStateException if that scope has already been closed | ||
| */ | ||
| public void attach(Pointer pointer) { | ||
| checkScope(); | ||
| if (pointers.add(pointer)) { | ||
| pointer.retainReference(); | ||
| } | ||
| } | ||
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| /** | ||
| * Detach a pointer from this scope. | ||
| * | ||
| * <p>Detaching a pointer from the scope will prevent its memory to be freed when closing the | ||
| * scope.</p> | ||
| * | ||
| * <p>If this {@code pointer} is not attached to this scope, this method has no effect.</p> | ||
| * | ||
| * @param pointer pointer to detach | ||
| * @throws IllegalStateException if that scope has already been closed | ||
| */ | ||
| public void detach(Pointer pointer) { | ||
| checkScope(); | ||
| if (pointers.remove(pointer)) { | ||
| pointer.releaseReference(); | ||
| } | ||
| } | ||
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| @Override | ||
| public synchronized void close() { | ||
| checkScope(); | ||
| pointers.forEach(Pointer::releaseReference); | ||
| pointers = null; | ||
| } | ||
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| private Set<Pointer> pointers = Collections.newSetFromMap(new WeakHashMap<>()); | ||
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| private void checkScope() { | ||
| if (pointers == null) { | ||
| throw new IllegalStateException("Pointer scope has been closed"); | ||
| } | ||
| } | ||
| } |
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114 changes: 114 additions & 0 deletions
114
...-core/tensorflow-core-api/src/test/java/org/tensorflow/internal/WeakPointerScopeTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,114 @@ | ||
| package org.tensorflow.internal; | ||
|
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| import static org.junit.jupiter.api.Assertions.assertEquals; | ||
| import static org.junit.jupiter.api.Assertions.assertFalse; | ||
| import static org.junit.jupiter.api.Assertions.assertNull; | ||
| import static org.junit.jupiter.api.Assertions.assertThrows; | ||
| import static org.junit.jupiter.api.Assertions.assertTrue; | ||
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| import org.bytedeco.javacpp.IntPointer; | ||
| import org.bytedeco.javacpp.Pointer; | ||
| import org.junit.jupiter.api.Test; | ||
| import org.tensorflow.EagerSession; | ||
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| public class WeakPointerScopeTest { | ||
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| @Test | ||
| public void resourcesAttachedAreFreedOnScopeClose() { | ||
| Pointer pointer = new IntPointer(10L); | ||
| assertEquals(0, pointer.referenceCount()); | ||
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| try (WeakPointerScope scope = new WeakPointerScope()) { | ||
| scope.attach(pointer); | ||
| assertEquals(1, pointer.referenceCount()); | ||
| } | ||
| assertTrue(pointer.isNull()); | ||
| } | ||
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| @Test | ||
| public void resourcesDetachedAreNotFreedOnScopeCloseWhenRetained() { | ||
| Pointer pointer = new IntPointer(10L); | ||
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| try (WeakPointerScope scope = new WeakPointerScope()) { | ||
| scope.attach(pointer); | ||
| scope.detach(pointer.retainReference()); | ||
| } | ||
| assertFalse(pointer.isNull()); | ||
| assertEquals(1, pointer.referenceCount()); | ||
| pointer.deallocate(); | ||
| } | ||
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| @Test | ||
| public void resourcesDetachedAreFreedWhenNotRetained() { | ||
| Pointer pointer = new IntPointer(10L); | ||
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| try (WeakPointerScope scope = new WeakPointerScope()) { | ||
| scope.attach(pointer); | ||
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| scope.detach(pointer); | ||
| assertTrue(pointer.isNull()); | ||
| } | ||
| } | ||
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| @Test | ||
| public void attachingResourceMoreThanOnceHasNoEffect() { | ||
| Pointer pointer = new IntPointer(10L); | ||
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| try (WeakPointerScope scope = new WeakPointerScope()) { | ||
| scope.attach(pointer); | ||
| scope.attach(pointer); | ||
| assertEquals(1, pointer.referenceCount()); | ||
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| Pointer pointerCopy = new Pointer(pointer); | ||
| assertEquals(1, pointerCopy.referenceCount()); | ||
| scope.attach(pointerCopy); | ||
| assertEquals(1, pointerCopy.referenceCount()); | ||
| } | ||
| assertTrue(pointer.isNull()); | ||
| } | ||
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| @Test | ||
| public void detachingUnattachedResourceHasNoEffect() { | ||
| Pointer pointer = new IntPointer(10L); | ||
| pointer.retainReference(); | ||
| assertEquals(1, pointer.referenceCount()); | ||
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| try (WeakPointerScope scope = new WeakPointerScope()) { | ||
| scope.detach(pointer); | ||
| assertEquals(1, pointer.referenceCount()); | ||
| } | ||
| assertFalse(pointer.isNull()); | ||
| pointer.deallocate(); | ||
| } | ||
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| @Test | ||
| public void operationOnClosedScopeFails() { | ||
| Pointer pointer = new IntPointer(10L); | ||
| WeakPointerScope scope = new WeakPointerScope(); | ||
| scope.close(); | ||
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| assertThrows(IllegalStateException.class, () -> scope.attach(pointer)); | ||
| assertThrows(IllegalStateException.class, () -> scope.detach(pointer)); | ||
| assertThrows(IllegalStateException.class, () -> scope.close()); | ||
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| pointer.deallocate(); | ||
| } | ||
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| @Test | ||
| public void attachingResourceDoesNotPreventItToBeGarbageCollected() throws InterruptedException { | ||
| try (WeakPointerScope scope = new WeakPointerScope()) { | ||
| Pointer pointer = new IntPointer(10L); | ||
| scope.attach(pointer); | ||
| System.gc(); | ||
| Thread.sleep(50); | ||
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| long before = Pointer.totalBytes(); | ||
| pointer = null; | ||
| System.gc(); | ||
| Thread.sleep(50); | ||
| long after = Pointer.totalBytes(); | ||
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| assertEquals(4 * 10L, before - after); | ||
| } | ||
| } | ||
| } |