[GitHub] [zookeeper] maoling commented on a change in pull request #1219: ZOOKEEPER-3427: Introduce SnapshotComparer that assists debugging with snapshots.

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

maoling commented on a change in pull request #1219: ZOOKEEPER-3427: Introduce SnapshotComparer that assists debugging with snapshots.
URL: https://github.com/apache/zookeeper/pull/1219#discussion_r366129666
 
 

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 File path: zookeeper-server/src/main/java/org/apache/zookeeper/server/SnapshotComparer.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.zookeeper.server;
+
+import java.io.File;
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Scanner;
+import java.util.zip.CheckedInputStream;
+import org.apache.commons.cli.BasicParser;
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.HelpFormatter;
+import org.apache.commons.cli.OptionBuilder;
+import org.apache.commons.cli.Options;
+import org.apache.commons.cli.ParseException;
+import org.apache.jute.BinaryInputArchive;
+import org.apache.jute.InputArchive;
+import org.apache.zookeeper.server.persistence.FileSnap;
+import org.apache.zookeeper.server.persistence.SnapStream;
+
+/**
+ * SnapshotComparer is a tool that loads and compares two snapshots, with configurable threshold and various filters.
+ * It's useful in use cases that involve snapshot analysis, such as offline data consistency checking, and data trending analysis (e.g. what's growing under which zNode path during when).
+ * Only outputs information about permanent nodes, ignoring both sessions and ephemeral nodes.
+ */
+public class SnapshotComparer {
+  private final Options options;
+  private static final String leftOption = "left";
+  private static final String rightOption = "right";
+  private static final String byteThresholdOption = "bytes";
+  private static final String nodeThresholdOption = "nodes";
+  private static final String debugOption = "debug";
+  private static final String interactiveOption = "interactive";
+
+  @SuppressWarnings("static")
+  private SnapshotComparer() {
+    options = new Options();
+    options.addOption(
+        OptionBuilder
+            .hasArg()
+            .isRequired(true)
+            .withLongOpt(leftOption)
+            .withDescription("(Required) The left snapshot file.")
+            .withArgName("LEFT")
+            .withType(File.class)
+            .create("l"));
+    options.addOption(
+        OptionBuilder
+            .hasArg()
+            .isRequired(true)
+            .withLongOpt(rightOption)
+            .withDescription("(Required) The right snapshot file.")
+            .withArgName("RIGHT")
+            .withType(File.class)
+            .create("r"));
+    options.addOption(
+        OptionBuilder
+            .hasArg()
+            .isRequired(true)
+            .withLongOpt(byteThresholdOption)
+            .withDescription("(Required) The node data delta size threshold, in bytes, for printing the node.")
+            .withArgName("BYTETHRESHOLD")
+            .withType(String.class)
+            .create("b"));
+    options.addOption(
+        OptionBuilder
+            .hasArg()
+            .isRequired(true)
+            .withLongOpt(nodeThresholdOption)
+            .withDescription("(Required) The descendant node delta size threshold, in nodes, for printing the node.")
+            .withArgName("NODETHRESHOLD")
+            .withType(String.class)
+            .create("n"));
+    options.addOption(
+        OptionBuilder
+            .hasArg()
+            .withLongOpt(debugOption)
+            .withDescription("Use debug output.")
+            .withArgName("DEBUG")
+            .withType(String.class)
+            .create("d"));
+    options.addOption(
+        OptionBuilder
+            .hasArg()
+            .withLongOpt(interactiveOption)
+            .withDescription("Enter interactive mode.")
+            .withArgName("INTERACTIVE")
+            .withType(String.class)
+            .create("i"));
+  }
+
+  private void usage() {
+    HelpFormatter help = new HelpFormatter();
+
+    help.printHelp(
+        120,
+        "java -cp <classPath> " + SnapshotComparer.class.getName(),
+        "",
+        options,
+        "");
+  }
+
+  public static void main(String[] args) throws Exception {
+    SnapshotComparer app = new SnapshotComparer();
+    app.compareSnapshots(args);
+  }
+
+  private void compareSnapshots(String[] args) throws Exception {
+    CommandLine parsedOptions;
+    try {
+      parsedOptions = new BasicParser().parse(options, args);
+    } catch (ParseException e) {
+      System.err.println(e.getMessage());
+      usage();
+      System.exit(-1);
+      return;
 
 Review comment:
   > [ERROR] org.apache.zookeeper.server.SnapshotComparer.compareSnapshots(String[]) invokes System.exit(...), which shuts down the entire virtual machine [org.apache.zookeeper.server.SnapshotComparer] At SnapshotComparer.java:[line 136] DM_EXIT
   
   a try for `ServiceUtils.requestSystemExit`

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