[GitHub] [arrow] jacques-n commented on a change in pull request #7030: ARROW-7808: [Java][Dataset] Implement Datasets Java API by JNI to C++
jacques-n commented on a change in pull request #7030:
URL: https://github.com/apache/arrow/pull/7030#discussion_r449967588
##
File path:
java/dataset/src/main/java/org/apache/arrow/memory/NativeUnderlingMemory.java
##
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.arrow.memory;
+
+import org.apache.arrow.dataset.jni.JniWrapper;
+
+/**
+ * AllocationManager implementation for Native allocated memory.
+ */
+public class NativeUnderlingMemory extends AllocationManager {
Review comment:
Not necessarily. When you allocate and deallocate memory in c++ you can
call (via reflection) java.nio.Bits.reserveMemory() and unreserveMemory(). If
you wanted to be extra fancy you could actually just do the reads/writes to the
underlying atomics. Alternatively, you could build a pooling impl for C++ that
uses the JNIEnv.NewDirectByteBuffer().
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[GitHub] [arrow] jacques-n commented on a change in pull request #7030: ARROW-7808: [Java][Dataset] Implement Datasets Java API by JNI to C++
jacques-n commented on a change in pull request #7030:
URL: https://github.com/apache/arrow/pull/7030#discussion_r449967588
##
File path:
java/dataset/src/main/java/org/apache/arrow/memory/NativeUnderlingMemory.java
##
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.arrow.memory;
+
+import org.apache.arrow.dataset.jni.JniWrapper;
+
+/**
+ * AllocationManager implementation for Native allocated memory.
+ */
+public class NativeUnderlingMemory extends AllocationManager {
Review comment:
Not necessarily. When you allocate and deallocate memory in c++ you can
call (via reflection) java.nio.Bits.reserveMemory() and unreserveMemory(). If
you wanted to be extra fancy you could actually just do the reads/writes to the
underlying atomics. Alternatively, you could build a pooling impl for C++ that
uses the JNIEnv. NewDirectByteBuffer.
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[GitHub] [arrow] jacques-n commented on a change in pull request #7030: ARROW-7808: [Java][Dataset] Implement Datasets Java API by JNI to C++
jacques-n commented on a change in pull request #7030:
URL: https://github.com/apache/arrow/pull/7030#discussion_r446237545
##
File path:
java/dataset/src/main/java/org/apache/arrow/memory/NativeUnderlingMemory.java
##
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.arrow.memory;
+
+import org.apache.arrow.dataset.jni.JniWrapper;
+
+/**
+ * AllocationManager implementation for Native allocated memory.
+ */
+public class NativeUnderlingMemory extends AllocationManager {
Review comment:
In reality, this is not at all the case. There are two ways that you run
out of memory in Java: you run out of available allocation space OR you hit the
limit at the JVM level. The limit at the JVM level can be influenced by things
like fragmentation so in nearly all cases you hit that limit before the
allocator managed limit. In your patch, you only are respecting the allocator
set limit, not the jvm limit. This means a user could configure java to allow X
of memory and the process actually will use 2X of memory, leading to issues in
many systems.
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[GitHub] [arrow] jacques-n commented on a change in pull request #7030: ARROW-7808: [Java][Dataset] Implement Datasets Java API by JNI to C++
jacques-n commented on a change in pull request #7030:
URL: https://github.com/apache/arrow/pull/7030#discussion_r439206598
##
File path: java/dataset/src/main/java/org/apache/arrow/memory/Ownerships.java
##
@@ -0,0 +1,47 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.arrow.memory;
+
+/**
+ * Utility class managing ownership's transferring between Native Arrow
buffers and Java Arrow buffers.
+ */
+public class Ownerships {
+ private static final Ownerships INSTANCE = new Ownerships();
+
+ private Ownerships() {
+ }
+
+ public static Ownerships get() {
+return INSTANCE;
+ }
+
+ /**
+ * Returned ledger's ref count is initialized or increased by 1.
+ */
+ public BufferLedger takeOwnership(BaseAllocator allocator, AllocationManager
allocationManager) {
+final BufferLedger ledger = allocationManager.associate(allocator);
+long size = allocationManager.getSize();
+boolean succeed = allocator.forceAllocate(size);
+if (!succeed) {
+ throw new OutOfMemoryException("Target allocator is full");
+}
+((BaseAllocator)
allocationManager.getOwningLedger().getAllocator()).releaseBytes(size);
Review comment:
We need to address this requirement another way. Package hacking isn't
the right solution and I believe you're violating the thread safety of the
allocator classes.
##
File path:
java/dataset/src/main/java/org/apache/arrow/memory/NativeUnderlingMemory.java
##
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.arrow.memory;
+
+import org.apache.arrow.dataset.jni.JniWrapper;
+
+/**
+ * AllocationManager implementation for Native allocated memory.
+ */
+public class NativeUnderlingMemory extends AllocationManager {
Review comment:
I think we should probably hold off on merging until we resolve this.
Just because another part of the codebase has debt or weaknesses doesn't mean
we should introduce more of that.
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