--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/sjavac/server/RequestHandler.java	Mon Feb 29 11:54:06 2016 +0100
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/sjavac/server/RequestHandler.java	Mon Feb 29 13:24:01 2016 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,19 +25,16 @@
 
 package com.sun.tools.sjavac.server;
 
-import static com.sun.tools.sjavac.server.SjavacServer.LINE_TYPE_RC;
-import static com.sun.tools.sjavac.server.SjavacServer.LINE_TYPE_STDERR;
-import static com.sun.tools.sjavac.server.SjavacServer.LINE_TYPE_STDOUT;
+import com.sun.tools.sjavac.Log;
+import com.sun.tools.sjavac.Util;
 
 import java.io.BufferedReader;
 import java.io.InputStreamReader;
 import java.io.PrintWriter;
-import java.io.StringWriter;
-import java.io.Writer;
 import java.net.Socket;
+import java.nio.file.Path;
 
-import com.sun.tools.sjavac.AutoFlushWriter;
-import com.sun.tools.sjavac.Log;
+import static com.sun.tools.sjavac.server.SjavacServer.LINE_TYPE_RC;
 
 
 /**
@@ -56,7 +53,7 @@
  *  This code and its internal interfaces are subject to change or
  *  deletion without notice.</b>
  */
-public class RequestHandler implements Runnable {
+public class RequestHandler extends Thread {
 
     private final Socket socket;
     private final Sjavac sjavac;
@@ -68,9 +65,30 @@
 
     @Override
     public void run() {
+
         try (BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
              PrintWriter out = new PrintWriter(socket.getOutputStream(), true)) {
 
+            // Set up logging for this thread. Stream back logging messages to
+            // client on the format format "level:msg".
+            Log.setLogForCurrentThread(new Log(out, out) {
+                @Override
+                protected boolean isLevelLogged(Level l) {
+                    // Make sure it is up to the client to decide whether or
+                    // not this message should be displayed.
+                    return true;
+                }
+
+                @Override
+                protected void printLogMsg(Level msgLevel, String msg) {
+                    // Follow sjavac server/client protocol: Send one line
+                    // at a time and prefix with message with "level:".
+                    Util.getLines(msg)
+                        .map(line -> msgLevel + ":" + line)
+                        .forEach(line -> super.printLogMsg(msgLevel, line));
+                }
+            });
+
             // Read argument array
             int n = Integer.parseInt(in.readLine());
             String[] args = new String[n];
@@ -78,23 +96,32 @@
                 args[i] = in.readLine();
             }
 
+            // If there has been any internal errors, notify client
+            checkInternalErrorLog();
+
             // Perform compilation
-            Writer stdout = new LinePrefixFilterWriter(new AutoFlushWriter(out), LINE_TYPE_STDOUT + ":");
-            Writer stderr = new LinePrefixFilterWriter(new AutoFlushWriter(out), LINE_TYPE_STDERR + ":");
-            int rc = sjavac.compile(args, stdout, stderr);
-            stdout.flush();
-            stderr.flush();
+            int rc = sjavac.compile(args);
 
             // Send return code back to client
             out.println(LINE_TYPE_RC + ":" + rc);
 
+            // Check for internal errors again.
+            checkInternalErrorLog();
         } catch (Exception ex) {
             // Not much to be done at this point. The client side request
             // code will most likely throw an IOException and the
             // compilation will fail.
-            StringWriter sw = new StringWriter();
-            ex.printStackTrace(new PrintWriter(sw));
-            Log.error(sw.toString());
+            Log.error(ex);
+        } finally {
+            Log.setLogForCurrentThread(null);
+        }
+    }
+
+    private void checkInternalErrorLog() {
+        Path errorLog = ServerMain.getErrorLog().getLogDestination();
+        if (errorLog != null) {
+            Log.error("Server has encountered an internal error. See " + errorLog.toAbsolutePath()
+                    + " for details.");
         }
     }
 }