[GitHub] [iotdb] JackieTien97 commented on a change in pull request #2080: Add continuous compaction in level compaction strategy

[GitBox <gi...@apache.org>]

JackieTien97 commented on a change in pull request #2080:
URL: https://github.com/apache/iotdb/pull/2080#discussion_r553681080



##########
File path: server/src/main/java/org/apache/iotdb/db/engine/cache/FileStatistics.java
##########
@@ -0,0 +1,56 @@
+/*
+ * 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.iotdb.db.engine.cache;
+
+import static org.apache.iotdb.tsfile.utils.RamUsageEstimator.NUM_BYTES_INT;
+import static org.apache.iotdb.tsfile.utils.RamUsageEstimator.NUM_BYTES_LONG;
+import static org.apache.iotdb.tsfile.utils.RamUsageEstimator.NUM_BYTES_OBJECT_REF;
+
+public class FileStatistics {
+
+  private long numOfPoints;
+  private int sensorNum;
+
+  public FileStatistics(long numOfPoints, int sensorNum) {
+    this.numOfPoints = numOfPoints;
+    this.sensorNum = sensorNum;
+  }
+
+  public long getNumOfPoints() {
+    return numOfPoints;
+  }
+
+  public void setNumOfPoints(long numOfPoints) {
+    this.numOfPoints = numOfPoints;
+  }
+
+  public int getSensorNum() {
+    return sensorNum;
+  }
+
+  public void setSensorNum(int sensorNum) {
+    this.sensorNum = sensorNum;
+  }
+
+
+  public long calculateRamSize() {
+    return NUM_BYTES_OBJECT_REF + NUM_BYTES_LONG + NUM_BYTES_INT;

Review comment:
       NUM_BYTES_OBJECT_REF is not equal to the object header size, you should use the NUM_BYTES_OBJECT_HEADER field in RamUsageEstimator.
   And by the way, jvm may also align the object, so this calculation may not be exact.

##########
File path: server/src/main/java/org/apache/iotdb/db/conf/IoTDBConfig.java
##########
@@ -421,6 +427,11 @@
    */
   private long allocateMemoryForChunkCache = allocateMemoryForRead / 10;
 
+  /**
+   * Memory allocated for file statistics cache in compaction process
+   */
+  private long allocateMemoryForFileStatisticsCache = allocateMemoryForRead / 100;

Review comment:
       Why this field does not have a corresponding property in iotdb-engine.properties.

##########
File path: server/src/main/java/org/apache/iotdb/db/engine/cache/FileStatisticsCache.java
##########
@@ -0,0 +1,145 @@
+/*
+ * 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.iotdb.db.engine.cache;
+
+import java.io.IOException;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import org.apache.iotdb.db.conf.IoTDBDescriptor;
+import org.apache.iotdb.db.engine.storagegroup.TsFileResource;
+import org.apache.iotdb.tsfile.file.metadata.ChunkMetadata;
+import org.apache.iotdb.tsfile.read.TsFileSequenceReader;
+import org.apache.iotdb.tsfile.utils.RamUsageEstimator;
+
+public class FileStatisticsCache {
+
+  private final ReadWriteLock lock = new ReentrantReadWriteLock();
+  private static LRULinkedHashMap<AccountableString, FileStatistics> fileStatisticsCache;
+  private static long MEMORY_THRESHOLD_IN_FILE_STATISTICS_CACHE = IoTDBDescriptor.getInstance()
+      .getConfig().getAllocateMemoryForFileStatisticsCache();
+
+  private FileStatisticsCache() {
+    fileStatisticsCache = new LRULinkedHashMap<AccountableString, FileStatistics>(
+        MEMORY_THRESHOLD_IN_FILE_STATISTICS_CACHE) {
+      @Override
+      protected long calEntrySize(AccountableString key, FileStatistics value) {
+        if (value == null) {
+          return RamUsageEstimator.sizeOf(key) + RamUsageEstimator.shallowSizeOf(value);

Review comment:
       There is no need to calculate FileStatistics size each time, because it's a constant value

##########
File path: server/src/main/java/org/apache/iotdb/db/engine/cache/FileStatisticsCache.java
##########
@@ -0,0 +1,145 @@
+/*
+ * 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.iotdb.db.engine.cache;
+
+import java.io.IOException;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import org.apache.iotdb.db.conf.IoTDBDescriptor;
+import org.apache.iotdb.db.engine.storagegroup.TsFileResource;
+import org.apache.iotdb.tsfile.file.metadata.ChunkMetadata;
+import org.apache.iotdb.tsfile.read.TsFileSequenceReader;
+import org.apache.iotdb.tsfile.utils.RamUsageEstimator;
+
+public class FileStatisticsCache {
+
+  private final ReadWriteLock lock = new ReentrantReadWriteLock();
+  private static LRULinkedHashMap<AccountableString, FileStatistics> fileStatisticsCache;
+  private static long MEMORY_THRESHOLD_IN_FILE_STATISTICS_CACHE = IoTDBDescriptor.getInstance()
+      .getConfig().getAllocateMemoryForFileStatisticsCache();
+
+  private FileStatisticsCache() {
+    fileStatisticsCache = new LRULinkedHashMap<AccountableString, FileStatistics>(
+        MEMORY_THRESHOLD_IN_FILE_STATISTICS_CACHE) {
+      @Override
+      protected long calEntrySize(AccountableString key, FileStatistics value) {
+        if (value == null) {
+          return RamUsageEstimator.sizeOf(key) + RamUsageEstimator.shallowSizeOf(value);
+        }
+        long entrySize;
+        if (count < 10) {
+          long currentSize = value.calculateRamSize();
+          averageSize = ((averageSize * count) + currentSize) / (++count);
+          entrySize = RamUsageEstimator.sizeOf(key)
+              + (currentSize + RamUsageEstimator.NUM_BYTES_OBJECT_REF)
+              + RamUsageEstimator.shallowSizeOf(value);
+        } else if (count < 100000) {
+          count++;
+          entrySize = RamUsageEstimator.sizeOf(key)
+              + (averageSize + RamUsageEstimator.NUM_BYTES_OBJECT_REF)
+              + RamUsageEstimator.shallowSizeOf(value);
+        } else {
+          averageSize = value.calculateRamSize();
+          count = 1;
+          entrySize = RamUsageEstimator.sizeOf(key)
+              + (averageSize + RamUsageEstimator.NUM_BYTES_OBJECT_REF)
+              + RamUsageEstimator.shallowSizeOf(value);
+        }
+        return entrySize;
+      }
+    };
+  }
+
+  public void put(String filePath, long totalPoint, int sensorNum) {
+    lock.writeLock().lock();
+    fileStatisticsCache
+        .put(new AccountableString(filePath), new FileStatistics(totalPoint, sensorNum));
+    lock.readLock().lock();
+  }
+
+  public FileStatistics get(TsFileResource fileResource) throws IOException {
+    String filePath = fileResource.getTsFilePath();
+    AccountableString key = new AccountableString(filePath);
+    if (fileStatisticsCache.containsKey(key)) {
+      lock.readLock().lock();
+      try {
+        return fileStatisticsCache.get(key);
+      } finally {
+        lock.readLock().unlock();
+      }
+    } else {
+      try (TsFileSequenceReader tsFileSequenceReader = new TsFileSequenceReader(
+          fileResource.getTsFilePath())) {
+        long totalPoints = 0;
+        Set<String> sensorSet = new HashSet<>();
+        List<String> devices = tsFileSequenceReader.getAllDevices();
+        for (String device : devices) {
+          Map<String, List<ChunkMetadata>> chunkMetadataListMap = tsFileSequenceReader
+              .readChunkMetadataInDevice(device);
+          for (List<ChunkMetadata> chunkMetadataList : chunkMetadataListMap.values()) {
+            for (ChunkMetadata chunkMetadata : chunkMetadataList) {
+              totalPoints += chunkMetadata.getNumOfPoints();
+              sensorSet.add(chunkMetadata.getMeasurementUid());

Review comment:
       This will cause differernt thread read from disk repeatedly

##########
File path: server/src/main/java/org/apache/iotdb/db/engine/cache/FileStatisticsCache.java
##########
@@ -0,0 +1,145 @@
+/*
+ * 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.iotdb.db.engine.cache;
+
+import java.io.IOException;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import org.apache.iotdb.db.conf.IoTDBDescriptor;
+import org.apache.iotdb.db.engine.storagegroup.TsFileResource;
+import org.apache.iotdb.tsfile.file.metadata.ChunkMetadata;
+import org.apache.iotdb.tsfile.read.TsFileSequenceReader;
+import org.apache.iotdb.tsfile.utils.RamUsageEstimator;
+
+public class FileStatisticsCache {

Review comment:
       It's better to add this cache to MBeans monitor.




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