[GitHub] [hbase] virajjasani commented on a change in pull request #600: HBASE-22460 : Reopen regions with very high Store Ref Counts

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virajjasani commented on a change in pull request #600: HBASE-22460 : Reopen regions with very high Store Ref Counts
URL: https://github.com/apache/hbase/pull/600#discussion_r326124979
 
 

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 File path: hbase-server/src/main/java/org/apache/hadoop/hbase/master/RegionsRecoveryChore.java
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+/*
+ * 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.hbase.master;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.ClusterMetrics;
+import org.apache.hadoop.hbase.RegionMetrics;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.ServerMetrics;
+import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.PerClientRandomNonceGenerator;
+import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hbase.thirdparty.org.apache.commons.collections4.MapUtils;
+
+/**
+ * This chore, every time it runs, will try to recover regions with high store ref count
+ * by reopening them
+ */
+@InterfaceAudience.Private
+public class RegionsRecoveryChore extends ScheduledChore {
+
+  private static final Logger LOG = LoggerFactory.getLogger(RegionsRecoveryChore.class);
+
+  private static final String REGIONS_RECOVERY_CHORE_NAME = "RegionsRecoveryChore";
+
+  private static final String REGIONS_RECOVERY_INTERVAL =
+    "hbase.master.regions.recovery.interval";
+  private static final String STORE_REF_COUNT_THRESHOLD = "hbase.regions.recovery.store.count";
+
+  private static final int DEFAULT_REGIONS_RECOVERY_INTERVAL = 1200 * 1000; // Default 20 min ?
+  private static final int DEFAULT_STORE_REF_COUNT_THRESHOLD = 256;
+
+  private static final String ERROR_REOPEN_REIONS_MSG =
+    "Error reopening regions with high storeRefCount. ";
+
+  private final HMaster hMaster;
+  private final int storeRefCountThreshold;
+
+  private static final PerClientRandomNonceGenerator NONCE_GENERATOR =
+    PerClientRandomNonceGenerator.get();
+
+  /**
+   * Construct RegionsRecoveryChore with provided params
+   *
+   * @param stopper When {@link Stoppable#isStopped()} is true, this chore will cancel and cleanup
+   * @param configuration The configuration params to be used
+   * @param hMaster HMaster instance to initiate RegionTableRegions
+   */
+  RegionsRecoveryChore(final Stoppable stopper, final Configuration configuration,
+      final HMaster hMaster) {
+
+    super(REGIONS_RECOVERY_CHORE_NAME, stopper, configuration.getInt(REGIONS_RECOVERY_INTERVAL,
+      DEFAULT_REGIONS_RECOVERY_INTERVAL));
+    this.hMaster = hMaster;
+    this.storeRefCountThreshold = configuration.getInt(STORE_REF_COUNT_THRESHOLD,
+      DEFAULT_STORE_REF_COUNT_THRESHOLD);
+
+  }
+
+  @Override
+  protected void chore() {
+    if (LOG.isTraceEnabled()) {
+      LOG.trace("Starting up Regions Recovery by reopening regions based on storeRefCount...");
+    }
+    try {
+      final ClusterMetrics clusterMetrics = hMaster.getClusterMetrics();
+      final Map<ServerName, ServerMetrics> serverMetricsMap =
+        clusterMetrics.getLiveServerMetrics();
+      final Map<TableName, List<byte[]>> tableToReopenRegionsMap =
+        getTableToRegionsByRefCount(serverMetricsMap);
+      if (MapUtils.isNotEmpty(tableToReopenRegionsMap)) {
+        tableToReopenRegionsMap.forEach((tableName, regionNames) -> {
+          try {
+            LOG.warn("Reopening regions due to high refCount. TableName: {} , noOfRegions: {}",
+              tableName, regionNames.size());
+            hMaster.reopenRegions(tableName, regionNames, NONCE_GENERATOR.getNonceGroup(),
+              NONCE_GENERATOR.newNonce());
+          } catch (IOException e) {
+            LOG.error("{} tableName: {}, regionNames: {}", ERROR_REOPEN_REIONS_MSG,
+              tableName, regionNames, e);
+          }
+        });
+      }
+    } catch (Exception e) {
+      LOG.error("Error while reopening regions based on storeRefCount threshold", e);
+    }
+    if (LOG.isTraceEnabled()) {
+      LOG.trace("Exiting Regions Recovery by reopening regions based on storeRefCount...");
+    }
+  }
+
+  private Map<TableName, List<byte[]>> getTableToRegionsByRefCount(
+      final Map<ServerName, ServerMetrics> serverMetricsMap) {
+
+    final Map<TableName, List<byte[]>> tableToReopenRegionsMap = new HashMap<>();
+    for (ServerMetrics serverMetrics : serverMetricsMap.values()) {
+      Map<byte[], RegionMetrics> regionMetricsMap = serverMetrics.getRegionMetrics();
+      for (RegionMetrics regionMetrics : regionMetricsMap.values()) {
+        // For each region, each store file can have different ref counts
+        // We need to find maximum of all such ref counts and if that max count
+        // is beyond a threshold value, we should reopen the region.
+        // Here, we take max ref count of all stores and not the cumulative count
+        // of all stores.
+        final int maxStoreRefCount = regionMetrics.getMaxStoreRefCount();
+        if (maxStoreRefCount > storeRefCountThreshold) {
 
 Review comment:
   Sure, better we exclude META? In your opinion, what default count (instead of 256) should be ideal?

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