TEZ-4038: Add a /prof profiler endpoint like HiveServer2 has

tez-common/src/main/java/org/apache/tez/common/TezUtilsInternal.java

@@ -21,6 +21,7 @@
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.lang.management.ManagementFactory;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.nio.charset.Charset;
@@ -322,6 +323,25 @@ public static <T extends Enum<T>> Set<T> getEnums(Configuration conf, String con
     return enums;
   }
 
+  public static Integer getPid() {
+    String pidStr = null;
+    String name = ManagementFactory.getRuntimeMXBean().getName();
+    if (name != null) {
+      int idx = name.indexOf("@");
+      if (idx != -1) {
+        pidStr = name.substring(0, name.indexOf("@"));
+      }
+    }
+    try {
+      if (pidStr != null) {
+        return Integer.valueOf(pidStr);
+      }
+    } catch (NumberFormatException nfe) {
+      LOG.info("Couldn't parse \"{}\" into integer pid", pidStr);
+    }
+    return null;
+  }
+
   @Private
   public static void setHadoopCallerContext(HadoopShim hadoopShim, TezTaskAttemptID attemptID) {
     hadoopShim.setHadoopCallerContext("tez_ta:" + attemptID.toString());

tez-common/src/main/java/org/apache/tez/common/web/ProfileOutputServlet.java

@@ -0,0 +1,66 @@
+/**
+ * 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.tez.common.web;
+
+import org.apache.hadoop.yarn.webapp.MimeType;
+import org.eclipse.jetty.servlet.DefaultServlet;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.File;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+/**
+ * Servlet to serve files generated by {@link ProfileServlet}.
+ */
+public class ProfileOutputServlet extends DefaultServlet {
+  public static final String FILE_QUERY_PARAM = "file";
+
+  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+    String queriedFile = request.getParameter(FILE_QUERY_PARAM);
+    if (queriedFile == null) {
+      writeMessage(response, "Run the profiler to be able to receive its output");
+      return;
+    }
+    File outputFile = new File(ProfileServlet.OUTPUT_DIR, queriedFile);
+    if (!outputFile.exists()) {
+      writeMessage(response, "Requested file does not exist: " + queriedFile);
+      return;
+    }
+    if (outputFile.length() < 100) {
+      response.setIntHeader("Refresh", 2);
+      writeMessage(response, "This page auto-refreshes every 2 seconds until output file is ready...");
+      return;
+    }
+    response.setContentType(MimeType.HTML);
+    response.getOutputStream().write(Files.readAllBytes(Paths.get(outputFile.getPath())));
+    response.getOutputStream().flush();
+    response.getOutputStream().close();
+  }
+
+  private void writeMessage(HttpServletResponse response, String message) throws IOException {
+    response.setContentType(MimeType.TEXT);
+    PrintWriter out = response.getWriter();
+    out.println(message);
+    out.close();
+  }
+}