Java tutorial
/** * Copyright The Apache Software Foundation * * 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.handler; import java.io.IOException; import java.io.InterruptedIOException; import java.util.Map; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.hbase.HRegionInfo; import org.apache.hadoop.hbase.RegionLoad; import org.apache.hadoop.hbase.ServerLoad; import org.apache.hadoop.hbase.ServerName; import org.apache.hadoop.hbase.exceptions.RegionOpeningException; import org.apache.hadoop.hbase.executor.EventHandler; import org.apache.hadoop.hbase.executor.EventType; import org.apache.hadoop.hbase.master.CatalogJanitor; import org.apache.hadoop.hbase.master.MasterServices; import org.apache.hadoop.hbase.master.RegionPlan; import org.apache.hadoop.hbase.master.RegionStates; import org.apache.hadoop.hbase.master.ServerManager; import org.apache.hadoop.hbase.util.EnvironmentEdgeManager; /** * Handles MERGE regions request on master: move the regions together(on the * same regionserver) and send MERGE RPC to regionserver. * * NOTE:The real merge is executed on the regionserver * */ @InterfaceAudience.Private public class DispatchMergingRegionHandler extends EventHandler { private static final Log LOG = LogFactory.getLog(DispatchMergingRegionHandler.class); private final MasterServices masterServices; private final CatalogJanitor catalogJanitor; private HRegionInfo region_a; private HRegionInfo region_b; private final boolean forcible; private final int timeout; public DispatchMergingRegionHandler(final MasterServices services, final CatalogJanitor catalogJanitor, final HRegionInfo region_a, final HRegionInfo region_b, final boolean forcible) { super(services, EventType.C_M_MERGE_REGION); this.masterServices = services; this.catalogJanitor = catalogJanitor; this.region_a = region_a; this.region_b = region_b; this.forcible = forcible; this.timeout = server.getConfiguration().getInt("hbase.master.regionmerge.timeout", 120 * 1000); } @Override public void process() throws IOException { boolean regionAHasMergeQualifier = !catalogJanitor.cleanMergeQualifier(region_a); if (regionAHasMergeQualifier || !catalogJanitor.cleanMergeQualifier(region_b)) { LOG.info("Skip merging regions " + region_a.getRegionNameAsString() + ", " + region_b.getRegionNameAsString() + ", because region " + (regionAHasMergeQualifier ? region_a.getEncodedName() : region_b.getEncodedName()) + " has merge qualifier"); return; } RegionStates regionStates = masterServices.getAssignmentManager().getRegionStates(); ServerName region_a_location = regionStates.getRegionServerOfRegion(region_a); ServerName region_b_location = regionStates.getRegionServerOfRegion(region_b); if (region_a_location == null || region_b_location == null) { LOG.info("Skip merging regions " + region_a.getRegionNameAsString() + ", " + region_b.getRegionNameAsString() + ", because region " + (region_a_location == null ? region_a.getEncodedName() : region_b.getEncodedName()) + " is not online now"); return; } long startTime = EnvironmentEdgeManager.currentTimeMillis(); boolean onSameRS = region_a_location.equals(region_b_location); // Make sure regions are on the same regionserver before send merge // regions request to regionserver if (!onSameRS) { // Move region_b to region a's location, switch region_a and region_b if // region_a's load lower than region_b's, so we will always move lower // load region RegionLoad loadOfRegionA = getRegionLoad(region_a_location, region_a); RegionLoad loadOfRegionB = getRegionLoad(region_b_location, region_b); if (loadOfRegionA != null && loadOfRegionB != null && loadOfRegionA.getRequestsCount() < loadOfRegionB.getRequestsCount()) { // switch region_a and region_b HRegionInfo tmpRegion = this.region_a; this.region_a = this.region_b; this.region_b = tmpRegion; ServerName tmpLocation = region_a_location; region_a_location = region_b_location; region_b_location = tmpLocation; } RegionPlan regionPlan = new RegionPlan(region_b, region_b_location, region_a_location); LOG.info("Moving regions to same server for merge: " + regionPlan.toString()); masterServices.getAssignmentManager().balance(regionPlan); while (!masterServices.isStopped()) { try { Thread.sleep(20); // Make sure check RIT first, then get region location, otherwise // we would make a wrong result if region is online between getting // region location and checking RIT boolean isRIT = regionStates.isRegionInTransition(region_b); region_b_location = masterServices.getAssignmentManager().getRegionStates() .getRegionServerOfRegion(region_b); onSameRS = region_a_location.equals(region_b_location); if (onSameRS || !isRIT) { // Regions are on the same RS, or region_b is not in // RegionInTransition any more break; } if ((EnvironmentEdgeManager.currentTimeMillis() - startTime) > timeout) break; } catch (InterruptedException e) { InterruptedIOException iioe = new InterruptedIOException(); iioe.initCause(e); throw iioe; } } } if (onSameRS) { startTime = EnvironmentEdgeManager.currentTimeMillis(); while (!masterServices.isStopped()) { try { masterServices.getServerManager().sendRegionsMerge(region_a_location, region_a, region_b, forcible); LOG.info( "Sent merge to server " + region_a_location + " for region " + region_a.getEncodedName() + "," + region_b.getEncodedName() + ", focible=" + forcible); break; } catch (RegionOpeningException roe) { if ((EnvironmentEdgeManager.currentTimeMillis() - startTime) > timeout) { LOG.warn("Failed sending merge to " + region_a_location + " after " + timeout + "ms", roe); break; } // Do a retry since region should be online on RS immediately } catch (IOException ie) { LOG.warn("Failed sending merge to " + region_a_location + " for region " + region_a.getEncodedName() + "," + region_b.getEncodedName() + ", focible=" + forcible, ie); break; } } } else { LOG.info("Cancel merging regions " + region_a.getRegionNameAsString() + ", " + region_b.getRegionNameAsString() + ", because can't move them together after " + (EnvironmentEdgeManager.currentTimeMillis() - startTime) + "ms"); } } private RegionLoad getRegionLoad(ServerName sn, HRegionInfo hri) { ServerManager serverManager = masterServices.getServerManager(); ServerLoad load = serverManager.getLoad(sn); if (load != null) { Map<byte[], RegionLoad> regionsLoad = load.getRegionsLoad(); if (regionsLoad != null) { return regionsLoad.get(hri.getRegionName()); } } return null; } }