sadanand48 commented on code in PR #9406: URL: https://github.com/apache/ozone/pull/9406#discussion_r2628543291
########## hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/snapshot/OMSnapshotDirectoryMetrics.java: ########## @@ -0,0 +1,399 @@ +/* + * 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.hadoop.ozone.om.snapshot; + +import static org.apache.hadoop.ozone.OzoneConsts.ROCKSDB_SST_SUFFIX; +import static org.apache.hadoop.ozone.om.OMConfigKeys.OZONE_OM_SNAPSHOT_DIRECTORY_METRICS_UPDATE_INTERVAL; +import static org.apache.hadoop.ozone.om.OMConfigKeys.OZONE_OM_SNAPSHOT_DIRECTORY_METRICS_UPDATE_INTERVAL_DEFAULT; + +import com.google.common.annotations.VisibleForTesting; +import java.io.File; +import java.io.IOException; +import java.nio.file.Files; +import java.nio.file.Path; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Map; +import java.util.Set; +import java.util.concurrent.Executors; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.ScheduledFuture; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicLong; +import java.util.stream.Collectors; +import java.util.stream.Stream; +import org.apache.hadoop.hdds.annotation.InterfaceAudience; +import org.apache.hadoop.hdds.conf.OzoneConfiguration; +import org.apache.hadoop.hdds.utils.IOUtils; +import org.apache.hadoop.hdds.utils.db.DBStore; +import org.apache.hadoop.hdds.utils.db.RDBStore; +import org.apache.hadoop.metrics2.MetricsCollector; +import org.apache.hadoop.metrics2.MetricsInfo; +import org.apache.hadoop.metrics2.MetricsSource; +import org.apache.hadoop.metrics2.MetricsSystem; +import org.apache.hadoop.metrics2.annotation.Metric; +import org.apache.hadoop.metrics2.annotation.Metrics; +import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem; +import org.apache.hadoop.metrics2.lib.MetricsRegistry; +import org.apache.hadoop.metrics2.lib.MutableGaugeLong; +import org.apache.hadoop.ozone.OzoneConsts; +import org.apache.hadoop.ozone.om.OMMetadataManager; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Metrics for tracking db.snapshots directory space usage and SST file counts. + * Provides both aggregate metrics and per-checkpoint-directory metrics. + * Metrics are updated asynchronously to avoid blocking operations. + */ [email protected] +@Metrics(about = "OM Snapshot Directory Metrics", context = OzoneConsts.OZONE) +public final class OMSnapshotDirectoryMetrics implements MetricsSource { + private static final Logger LOG = + LoggerFactory.getLogger(OMSnapshotDirectoryMetrics.class); + private static final String SOURCE_NAME = + OMSnapshotDirectoryMetrics.class.getSimpleName(); + + // Aggregate metrics + private @Metric MutableGaugeLong dbSnapshotsDirSize; + private @Metric MutableGaugeLong totalSstFilesCount; + private @Metric MutableGaugeLong numSnapshots; + + private final AtomicLong lastUpdateTime = new AtomicLong(0); + private final OMMetadataManager metadataManager; + private final MetricsRegistry registry = new MetricsRegistry(SOURCE_NAME); + + // Per-checkpoint-directory metrics storage + private volatile Map<String, CheckpointMetrics> checkpointMetricsMap = new HashMap<>(); + private ScheduledExecutorService updateExecutor; + private ScheduledFuture<?> updateTask; + + /** + * Starts the periodic metrics update task. + * + * @param conf OzoneConfiguration for reading update interval + */ + public void start(OzoneConfiguration conf) { + long updateInterval = conf.getTimeDuration(OZONE_OM_SNAPSHOT_DIRECTORY_METRICS_UPDATE_INTERVAL, + OZONE_OM_SNAPSHOT_DIRECTORY_METRICS_UPDATE_INTERVAL_DEFAULT, + TimeUnit.MILLISECONDS); + + updateExecutor = Executors.newSingleThreadScheduledExecutor(r -> { + Thread t = new Thread(r, "OMSnapshotDirectoryMetricsUpdate"); + t.setDaemon(true); + return t; + }); + + // Schedule periodic updates + updateTask = updateExecutor.scheduleWithFixedDelay(() -> { + try { + updateMetrics(); + lastUpdateTime.set(System.currentTimeMillis()); + } catch (Exception e) { + LOG.warn("Failed to update snapshot directory metrics", e); + } + }, 0, updateInterval, TimeUnit.MILLISECONDS); + } + + /** + * Stops the periodic metrics update task. + */ + public void stop() { + if (updateTask != null) { + updateTask.cancel(false); // Don't interrupt if running + updateTask = null; + } + + if (updateExecutor != null) { + updateExecutor.shutdown(); + try { + // Wait for any running updateMetrics() to complete (with timeout) + if (!updateExecutor.awaitTermination(30, TimeUnit.SECONDS)) { + LOG.warn("Metrics update executor did not terminate in time, forcing shutdown"); + updateExecutor.shutdownNow(); + // Wait a bit more for cancellation to take effect + if (!updateExecutor.awaitTermination(5, TimeUnit.SECONDS)) { + LOG.error("Metrics update executor did not terminate after force shutdown"); + } + } + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + updateExecutor.shutdownNow(); + } + updateExecutor = null; + } + } + + public void unRegister() { + stop(); + MetricsSystem ms = DefaultMetricsSystem.instance(); + ms.unregisterSource(SOURCE_NAME); + } + + /** + * Internal class to store per-checkpoint metrics. + */ + private static class CheckpointMetrics { + private final long size; + private final int sstFileCount; + + CheckpointMetrics(long size, int sstFileCount) { + this.size = size; + this.sstFileCount = sstFileCount; + } + + public long getSize() { + return size; + } + + public int getSstFileCount() { + return sstFileCount; + } + } + + private OMSnapshotDirectoryMetrics(OMMetadataManager metadataManager) { + this.metadataManager = metadataManager; + } + + public static OMSnapshotDirectoryMetrics create(String parent, + OMMetadataManager metadataManager) { + MetricsSystem ms = DefaultMetricsSystem.instance(); + return ms.register(SOURCE_NAME, + parent, + new OMSnapshotDirectoryMetrics(metadataManager)); + } + + /** + * Updates all metrics synchronously - both aggregate and per-checkpoint-directory. + */ + @VisibleForTesting + void updateMetrics() throws IOException { + DBStore store = metadataManager.getStore(); + if (!(store instanceof RDBStore)) { + LOG.debug("Store is not RDBStore, skipping snapshot directory metrics update"); + resetMetrics(); + return; + } + + RDBStore rdbStore = (RDBStore) store; + String snapshotsParentDir = rdbStore.getSnapshotsParentDir(); + + if (snapshotsParentDir == null) { + resetMetrics(); + return; + } + + File snapshotsDir = new File(snapshotsParentDir); + if (!snapshotsDir.exists() || !snapshotsDir.isDirectory()) { + resetMetrics(); + return; + } + + try { + // Check for interruption before expensive operations + if (Thread.currentThread().isInterrupted()) { + LOG.info("Metrics update interrupted, skipping"); + return; + } + + // Calculate aggregate metrics + long totalSize = calculateDirSizeAccountingForHardlinks(snapshotsDir); + dbSnapshotsDirSize.set(totalSize); + + // Calculate per-checkpoint-directory metrics and aggregate totals + File[] checkpointDirs = snapshotsDir.listFiles(File::isDirectory); + int totalSstCount = 0; + int snapshotCount = 0; + Map<String, CheckpointMetrics> newCheckpointMetricsMap = new HashMap<>(); + + if (checkpointDirs != null) { + snapshotCount = checkpointDirs.length; + + for (File checkpointDir : checkpointDirs) { + String checkpointDirName = checkpointDir.getName(); + long checkpointSize = 0; + int sstFileCount = 0; + + try { + checkpointSize = calculateDirSizeAccountingForHardlinks(checkpointDir); + File[] sstFiles = checkpointDir.listFiles((dir, name) -> + name.toLowerCase().endsWith(ROCKSDB_SST_SUFFIX)); + if (sstFiles != null) { + sstFileCount = sstFiles.length; + } + } catch (Exception e) { + LOG.debug("Error calculating metrics for checkpoint directory {}", + checkpointDirName, e); + // Continue with other directories even if one fails + continue; + } + + totalSstCount += sstFileCount; + newCheckpointMetricsMap.put(checkpointDirName, + new CheckpointMetrics(checkpointSize, sstFileCount)); + } + } + + // Update aggregate metrics + totalSstFilesCount.set(totalSstCount); + numSnapshots.set(snapshotCount); + + // Atomically update per-checkpoint metrics map + checkpointMetricsMap = Collections.unmodifiableMap(newCheckpointMetricsMap); + + if (LOG.isDebugEnabled()) { + LOG.debug("Updated snapshot directory metrics: size={}, sstFiles={}, snapshots={}", + totalSize, totalSstCount, snapshotCount); + } + + } catch (Exception e) { + LOG.warn("Error calculating snapshot directory metrics", e); + resetMetrics(); + } + } + + /** + * Calculates directory size accounting for hardlinks. + * (only counts each inode once). + * Uses Files.getAttribute to get the inode number and tracks + * visited inodes. + * + * @param directory the directory to calculate size for + * @return total size in bytes, counting each inode only once + */ + private long calculateDirSizeAccountingForHardlinks(File directory) + throws IOException { + Set<Object> visitedInodes = new HashSet<>(); Review Comment: the directory here is the db.snapshots/checkpointState dir that has all checkpoint dirs so we should be good -- This is an automated message from the Apache Git Service. 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