[GR-65896] Dynamic Heap Size Manager for Serial GC

Arash Kazemi Koohbanani · Arash Kazemi Koohbanani · commit 249ede38c524 · 2025-06-17T10:51:58.000Z
PullRequest: graal/19634
diff --git a/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/AbstractCollectionPolicy.java b/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/AbstractCollectionPolicy.java
@@ -349,7 +349,7 @@ protected SizeParameters computeSizeParameters(SizeParameters existing) {
         UnsignedWord heapSizeLimit = UnsignedUtils.max(alignDown(getHeapSizeLimit()), minAllSpaces);
 
         UnsignedWord maxHeap;
-        long optionMax = SubstrateGCOptions.MaxHeapSize.getValue();
+        long optionMax = getMaximumHeapSizeOptionValue();
         if (optionMax > 0L) {
             maxHeap = Word.unsigned(optionMax);
         } else {
@@ -418,6 +418,10 @@ protected UnsignedWord getYoungSizeLimit(UnsignedWord maxHeap) {
         return maxHeap.subtract(minSpaceSize());
     }
 
+    protected long getMaximumHeapSizeOptionValue() {
+        return SubstrateGCOptions.MaxHeapSize.getValue();
+    }
+
     protected UnsignedWord getInitialHeapSize() {
         return AbstractCollectionPolicy.INITIAL_HEAP_SIZE;
     }
diff --git a/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/CollectionPolicy.java b/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/CollectionPolicy.java
@@ -80,6 +80,8 @@ static Class<? extends CollectionPolicy> getPolicyClass(String name) {
                 return BasicCollectionPolicies.OnlyIncrementally.class;
             case "NeverCollect":
                 return BasicCollectionPolicies.NeverCollect.class;
+            case "Dynamic":
+                return DynamicCollectionPolicy.class;
         }
         throw UserError.abort("Policy %s does not exist.", name);
     }
@@ -210,4 +212,9 @@ static boolean shouldCollectYoungGenSeparately(boolean defaultValue) {
 
     /** Called before the end of a collection, in the safepoint operation. */
     void onCollectionEnd(boolean completeCollection, GCCause cause);
+
+    /** Can be overridden to recover from OOM. */
+    default boolean isOutOfMemory(UnsignedWord usedBytes) {
+        return usedBytes.aboveThan(getMaximumHeapSize());
+    }
 }
diff --git a/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/DynamicCollectionPolicy.java b/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/DynamicCollectionPolicy.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2025, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.svm.core.genscavenge;
+
+import org.graalvm.nativeimage.ImageSingletons;
+import org.graalvm.word.UnsignedWord;
+
+import com.oracle.svm.core.SubstrateGCOptions;
+import com.oracle.svm.core.heap.DynamicHeapSizeManager;
+
+/**
+ * This class provides the implementation of a dynamic collection policy that calls into an instance
+ * of {@link DynamicHeapSizeManager} if it exists, otherwise the implementation is equivalent to
+ * {@link AdaptiveCollectionPolicy}.
+ */
+class DynamicCollectionPolicy extends AdaptiveCollectionPolicy {
+    @Override
+    public String getName() {
+        return "dynamic";
+    }
+
+    @Override
+    protected long getMaximumHeapSizeOptionValue() {
+        if (ImageSingletons.contains(DynamicHeapSizeManager.class)) {
+            return ImageSingletons.lookup(DynamicHeapSizeManager.class).maxHeapSize().rawValue();
+        }
+
+        return SubstrateGCOptions.MaxHeapSize.getValue();
+    }
+
+    @Override
+    public boolean isOutOfMemory(UnsignedWord usedBytes) {
+        if (ImageSingletons.contains(DynamicHeapSizeManager.class)) {
+            return ImageSingletons.lookup(DynamicHeapSizeManager.class).outOfMemory(usedBytes);
+        }
+
+        return super.isOutOfMemory(usedBytes);
+    }
+}
diff --git a/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/GCImpl.java b/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/GCImpl.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -169,6 +169,9 @@ public void maybeCollectOnAllocation(UnsignedWord allocationSize) {
         } else if (getPolicy().shouldCollectOnAllocation()) {
             AllocationRequiringGCEvent.emit(getCollectionEpoch(), allocationSize);
             outOfMemory = collectWithoutAllocating(GenScavengeGCCause.OnAllocation, false);
+            if (outOfMemory) {
+                outOfMemory = getPolicy().isOutOfMemory(HeapImpl.getAccounting().getUsedBytes());
+            }
         }
         if (outOfMemory) {
             throw OutOfMemoryUtil.heapSizeExceeded();
@@ -186,7 +189,11 @@ private void collect(GCCause cause, boolean forceFullGC) {
         if (!hasNeverCollectPolicy()) {
             boolean outOfMemory = collectWithoutAllocating(cause, forceFullGC);
             if (outOfMemory) {
-                throw OutOfMemoryUtil.heapSizeExceeded();
+                if (getPolicy().isOutOfMemory(HeapImpl.getAccounting().getUsedBytes())) {
+                    throw OutOfMemoryUtil.heapSizeExceeded();
+                } else {
+                    GCImpl.getPolicy().updateSizeParameters();
+                }
             }
         }
     }
diff --git a/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/ThreadLocalAllocation.java b/substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/ThreadLocalAllocation.java
@@ -262,7 +262,7 @@ public static Object slowPathNewArrayLikeObject(Word objectHeader, int length, b
          * object is allocated and survives.
          */
         GCImpl.getPolicy().ensureSizeParametersInitialized();
-        if (size.aboveOrEqual(GCImpl.getPolicy().getMaximumHeapSize()) && !GCImpl.shouldIgnoreOutOfMemory()) {
+        if (GCImpl.getPolicy().isOutOfMemory(size) && !GCImpl.shouldIgnoreOutOfMemory()) {
             OutOfMemoryError outOfMemoryError = new OutOfMemoryError("Array allocation too large.");
             throw OutOfMemoryUtil.reportOutOfMemoryError(outOfMemoryError);
         }
diff --git a/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/heap/DynamicHeapSizeManager.java b/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/heap/DynamicHeapSizeManager.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2025, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.svm.core.heap;
+
+import static com.oracle.svm.core.heap.RestrictHeapAccess.Access.NO_ALLOCATION;
+
+import org.graalvm.word.UnsignedWord;
+
+import com.oracle.svm.core.SubstrateGCOptions;
+
+/**
+ * This interface defines the functions needed to implement a dynamic heap size manager, where the
+ * Java heap size can be changed at runtime.
+ */
+public interface DynamicHeapSizeManager {
+    /**
+     * Retrieves the current max heap size, overrides {@link SubstrateGCOptions#MaxHeapSize}.
+     *
+     * @return max heap size
+     */
+    @RestrictHeapAccess(access = NO_ALLOCATION, reason = "Called from allocation-free code paths.")
+    UnsignedWord maxHeapSize();
+
+    /**
+     * In case of OOM, try to request additional memory.
+     *
+     * @param bytes memory required
+     * @return true if out of memory, false if max heap size was increased
+     */
+    @RestrictHeapAccess(access = NO_ALLOCATION, reason = "Called from allocation-free code paths.")
+    boolean outOfMemory(UnsignedWord bytes);
+}
diff --git a/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/heap/dump/HeapDumpSupportImpl.java b/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/heap/dump/HeapDumpSupportImpl.java
@@ -201,13 +201,16 @@ private class HeapDumpOperation extends NativeVMOperation {
         }
 
         @Override
-        @RestrictHeapAccess(access = NO_ALLOCATION, reason = "Heap dumping must not allocate.")
         protected void operate(NativeVMOperationData d) {
             HeapDumpVMOperationData data = (HeapDumpVMOperationData) d;
             if (data.getGCBefore()) {
                 Heap.getHeap().getGC().collectCompletely(GCCause.HeapDump);
             }
+            dumpHeap(data);
+        }
 
+        @RestrictHeapAccess(access = NO_ALLOCATION, reason = "Heap dumping must not allocate.")
+        private void dumpHeap(HeapDumpVMOperationData data) {
             try {
                 boolean success = writer.dumpHeap(data.getRawFileDescriptor());
                 data.setSuccess(success);

Original file line number	Diff line number	Diff line change
`@@ -80,6 +80,8 @@ static Class<? extends CollectionPolicy> getPolicyClass(String name) {`
`80`	`80`	`return BasicCollectionPolicies.OnlyIncrementally.class;`
`81`	`81`	`case "NeverCollect":`
`82`	`82`	`return BasicCollectionPolicies.NeverCollect.class;`
	`83`	`+ case "Dynamic":`
	`84`	`+ return DynamicCollectionPolicy.class;`
`83`	`85`	`}`
`84`	`86`	`throw UserError.abort("Policy %s does not exist.", name);`
`85`	`87`	`}`
`@@ -210,4 +212,9 @@ static boolean shouldCollectYoungGenSeparately(boolean defaultValue) {`
`210`	`212`
`211`	`213`	`/** Called before the end of a collection, in the safepoint operation. */`
`212`	`214`	`void onCollectionEnd(boolean completeCollection, GCCause cause);`
	`215`	`+`
	`216`	`+ /** Can be overridden to recover from OOM. */`
	`217`	`+ default boolean isOutOfMemory(UnsignedWord usedBytes) {`
	`218`	`+ return usedBytes.aboveThan(getMaximumHeapSize());`
	`219`	`+ }`
`213`	`220`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,5 @@`
`1`	`1`	`/*`
`2`		`- * Copyright (c) 2013, 2023, Oracle and/or its affiliates. All rights reserved.`
	`2`	`+ * Copyright (c) 2013, 2025, Oracle and/or its affiliates. All rights reserved.`
`3`	`3`	`* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.`
`4`	`4`	`*`
`5`	`5`	`* This code is free software; you can redistribute it and/or modify it`
`@@ -169,6 +169,9 @@ public void maybeCollectOnAllocation(UnsignedWord allocationSize) {`
`169`	`169`	`} else if (getPolicy().shouldCollectOnAllocation()) {`
`170`	`170`	`AllocationRequiringGCEvent.emit(getCollectionEpoch(), allocationSize);`
`171`	`171`	`outOfMemory = collectWithoutAllocating(GenScavengeGCCause.OnAllocation, false);`
	`172`	`+ if (outOfMemory) {`
	`173`	`+ outOfMemory = getPolicy().isOutOfMemory(HeapImpl.getAccounting().getUsedBytes());`
	`174`	`+ }`
`172`	`175`	`}`
`173`	`176`	`if (outOfMemory) {`
`174`	`177`	`throw OutOfMemoryUtil.heapSizeExceeded();`
`@@ -186,7 +189,11 @@ private void collect(GCCause cause, boolean forceFullGC) {`
`186`	`189`	`if (!hasNeverCollectPolicy()) {`
`187`	`190`	`boolean outOfMemory = collectWithoutAllocating(cause, forceFullGC);`
`188`	`191`	`if (outOfMemory) {`
`189`		`- throw OutOfMemoryUtil.heapSizeExceeded();`
	`192`	`+ if (getPolicy().isOutOfMemory(HeapImpl.getAccounting().getUsedBytes())) {`
	`193`	`+ throw OutOfMemoryUtil.heapSizeExceeded();`
	`194`	`+ } else {`
	`195`	`+ GCImpl.getPolicy().updateSizeParameters();`
	`196`	`+ }`
`190`	`197`	`}`
`191`	`198`	`}`
`192`	`199`	`}`
Original file line number	Diff line number	Diff line change
`@@ -262,7 +262,7 @@ public static Object slowPathNewArrayLikeObject(Word objectHeader, int length, b`
`262`	`262`	`* object is allocated and survives.`
`263`	`263`	`*/`
`264`	`264`	`GCImpl.getPolicy().ensureSizeParametersInitialized();`
`265`		`- if (size.aboveOrEqual(GCImpl.getPolicy().getMaximumHeapSize()) && !GCImpl.shouldIgnoreOutOfMemory()) {`
	`265`	`+ if (GCImpl.getPolicy().isOutOfMemory(size) && !GCImpl.shouldIgnoreOutOfMemory()) {`
`266`	`266`	`OutOfMemoryError outOfMemoryError = new OutOfMemoryError("Array allocation too large.");`
`267`	`267`	`throw OutOfMemoryUtil.reportOutOfMemoryError(outOfMemoryError);`
`268`	`268`	`}`