[GitHub] [accumulo] milleruntime commented on a change in pull request #1891: Add TabletBalancer to SPI package

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

milleruntime commented on a change in pull request #1891:
URL: https://github.com/apache/accumulo/pull/1891#discussion_r570484856



##########
File path: core/src/main/java/org/apache/accumulo/core/spi/balancer/SimpleLoadBalancer.java
##########
@@ -0,0 +1,380 @@
+/*
+ * 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.accumulo.core.spi.balancer;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Objects;
+import java.util.Set;
+import java.util.SortedMap;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.accumulo.core.client.AccumuloException;
+import org.apache.accumulo.core.client.AccumuloSecurityException;
+import org.apache.accumulo.core.data.TableId;
+import org.apache.accumulo.core.data.TabletId;
+import org.apache.accumulo.core.manager.balancer.TabletServerIdImpl;
+import org.apache.accumulo.core.spi.balancer.data.TServerStatus;
+import org.apache.accumulo.core.spi.balancer.data.TableStatistics;
+import org.apache.accumulo.core.spi.balancer.data.TabletMigration;
+import org.apache.accumulo.core.spi.balancer.data.TabletServerId;
+import org.apache.accumulo.core.spi.balancer.data.TabletStatistics;
+import org.apache.accumulo.core.spi.balancer.util.ThrottledBalancerProblemReporter;
+import org.apache.accumulo.core.spi.balancer.util.ThrottledBalancerProblemReporter.OutstandingMigrationsProblem;
+import org.apache.accumulo.core.spi.balancer.util.ThrottledBalancerProblemReporter.Problem;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A simple tablet balancer that attempts to spread tablets out evenly across all available tablet
+ * servers. The goal is to achieve the same number of tablets on each tablet server.
+ *
+ * <p>
+ * Initial assignments attempt to maintain locality by assigning tablets to their previous location
+ * if possible, but otherwise assignments are made in a random fashion across all available tablet
+ * servers.
+ *
+ * @since 2.1.0
+ */
+public class SimpleLoadBalancer implements TabletBalancer {

Review comment:
       I assume this was just copied from `DefaultLoadBalancer`? It would be nice to mention this in the javadoc since it is difficult to track a file that was moved and renamed. The 

##########
File path: core/src/main/java/org/apache/accumulo/core/spi/balancer/SimpleLoadBalancer.java
##########
@@ -0,0 +1,380 @@
+/*
+ * 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.accumulo.core.spi.balancer;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Objects;
+import java.util.Set;
+import java.util.SortedMap;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.accumulo.core.client.AccumuloException;
+import org.apache.accumulo.core.client.AccumuloSecurityException;
+import org.apache.accumulo.core.data.TableId;
+import org.apache.accumulo.core.data.TabletId;
+import org.apache.accumulo.core.manager.balancer.TabletServerIdImpl;
+import org.apache.accumulo.core.spi.balancer.data.TServerStatus;
+import org.apache.accumulo.core.spi.balancer.data.TableStatistics;
+import org.apache.accumulo.core.spi.balancer.data.TabletMigration;
+import org.apache.accumulo.core.spi.balancer.data.TabletServerId;
+import org.apache.accumulo.core.spi.balancer.data.TabletStatistics;
+import org.apache.accumulo.core.spi.balancer.util.ThrottledBalancerProblemReporter;
+import org.apache.accumulo.core.spi.balancer.util.ThrottledBalancerProblemReporter.OutstandingMigrationsProblem;
+import org.apache.accumulo.core.spi.balancer.util.ThrottledBalancerProblemReporter.Problem;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A simple tablet balancer that attempts to spread tablets out evenly across all available tablet
+ * servers. The goal is to achieve the same number of tablets on each tablet server.
+ *
+ * <p>
+ * Initial assignments attempt to maintain locality by assigning tablets to their previous location
+ * if possible, but otherwise assignments are made in a random fashion across all available tablet
+ * servers.
+ *
+ * @since 2.1.0
+ */
+public class SimpleLoadBalancer implements TabletBalancer {

Review comment:
       I assume this was just copied from `DefaultLoadBalancer`? It would be nice to mention this in the javadoc since it is difficult to track a file that was moved and renamed.




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org