diff -r 000000000000 -r 959103a6100f src/share/classes/com/sun/tools/sjavac/CompileJavaPackages.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/classes/com/sun/tools/sjavac/CompileJavaPackages.java	Wed Apr 27 01:34:52 2016 +0800
@@ -0,0 +1,345 @@
+/*
+ * Copyright (c) 2012, 2013, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.tools.sjavac;
+
+import java.net.URI;
+import java.util.Arrays;
+import java.util.Random;
+import java.util.Set;
+import java.util.Map;
+
+import com.sun.tools.sjavac.server.JavacServer;
+import com.sun.tools.sjavac.server.SysInfo;
+import java.io.PrintStream;
+
+/**
+ * This transform compiles a set of packages containing Java sources.
+ * The compile request is divided into separate sets of source files.
+ * For each set a separate request thread is dispatched to a javac server
+ * and the meta data is accumulated. The number of sets correspond more or
+ * less to the number of cores. Less so now, than it will in the future.
+ *
+ * <p><b>This is NOT part of any supported API.
+ * If you write code that depends on this, you do so at your own
+ * risk.  This code and its internal interfaces are subject to change
+ * or deletion without notice.</b></p>
+ */
+public class CompileJavaPackages implements Transformer {
+
+    // The current limited sharing of data between concurrent JavaCompilers
+    // in the server will not give speedups above 3 cores. Thus this limit.
+    // We hope to improve this in the future.
+    final static int limitOnConcurrency = 3;
+
+    String serverSettings;
+    public void setExtra(String e) {
+        serverSettings = e;
+    }
+
+    String[] args;
+    public void setExtra(String[] a) {
+        args = a;
+    }
+
+    public boolean transform(Map<String,Set<URI>> pkgSrcs,
+                             Set<URI>             visibleSources,
+                             Map<URI,Set<String>> visibleClasses,
+                             Map<String,Set<String>> oldPackageDependents,
+                             URI destRoot,
+                             final Map<String,Set<URI>>    packageArtifacts,
+                             final Map<String,Set<String>> packageDependencies,
+                             final Map<String,String>      packagePubapis,
+                             int debugLevel,
+                             boolean incremental,
+                             int numCores,
+                             PrintStream out,
+                             PrintStream err)
+    {
+        boolean rc = true;
+        boolean concurrentCompiles = true;
+
+        // Fetch the id.
+        String id = Util.extractStringOption("id", serverSettings);
+        if (id == null || id.equals("")) {
+            // No explicit id set. Create a random id so that the requests can be
+            // grouped properly in the server.
+            id = "id"+(((new Random()).nextLong())&Long.MAX_VALUE);
+        }
+        // Only keep portfile and sjavac settings..
+        String psServerSettings = Util.cleanSubOptions("--server:", Util.set("portfile","sjavac","background","keepalive"), serverSettings);
+
+        // Get maximum heap size from the server!
+        SysInfo sysinfo = JavacServer.connectGetSysInfo(psServerSettings, out, err);
+        if (sysinfo.numCores == -1) {
+            Log.error("Could not query server for sysinfo!");
+            return false;
+        }
+        int numMBytes = (int)(sysinfo.maxMemory / ((long)(1024*1024)));
+        Log.debug("Server reports "+numMBytes+"MiB of memory and "+sysinfo.numCores+" cores");
+
+        if (numCores <= 0) {
+            // Set the requested number of cores to the number of cores on the server.
+            numCores = sysinfo.numCores;
+            Log.debug("Number of jobs not explicitly set, defaulting to "+sysinfo.numCores);
+        } else if (sysinfo.numCores < numCores) {
+            // Set the requested number of cores to the number of cores on the server.
+            Log.debug("Limiting jobs from explicitly set "+numCores+" to cores available on server: "+sysinfo.numCores);
+            numCores = sysinfo.numCores;
+        } else {
+            Log.debug("Number of jobs explicitly set to "+numCores);
+        }
+        // More than three concurrent cores does not currently give a speedup, at least for compiling the jdk
+        // in the OpenJDK. This will change in the future.
+        int numCompiles = numCores;
+        if (numCores > limitOnConcurrency) numCompiles = limitOnConcurrency;
+        // Split the work up in chunks to compiled.
+
+        int numSources = 0;
+        for (String s : pkgSrcs.keySet()) {
+            Set<URI> ss = pkgSrcs.get(s);
+            numSources += ss.size();
+        }
+
+        int sourcesPerCompile = numSources / numCompiles;
+
+        // For 64 bit Java, it seems we can compile the OpenJDK 8800 files with a 1500M of heap
+        // in a single chunk, with reasonable performance.
+        // For 32 bit java, it seems we need 1G of heap.
+        // Number experimentally determined when compiling the OpenJDK.
+        // Includes space for reasonably efficient garbage collection etc,
+        // Calculating backwards gives us a requirement of
+        // 1500M/8800 = 175 KiB for 64 bit platforms
+        // and 1G/8800 = 119 KiB for 32 bit platform
+        // for each compile.....
+        int kbPerFile = 175;
+        String osarch = System.getProperty("os.arch");
+        String dataModel = System.getProperty("sun.arch.data.model");
+        if ("32".equals(dataModel)) {
+            // For 32 bit platforms, assume it is slightly smaller
+            // because of smaller object headers and pointers.
+            kbPerFile = 119;
+        }
+        int numRequiredMBytes = (kbPerFile*numSources)/1024;
+        Log.debug("For os.arch "+osarch+" the empirically determined heap required per file is "+kbPerFile+"KiB");
+        Log.debug("Server has "+numMBytes+"MiB of heap.");
+        Log.debug("Heuristics say that we need "+numRequiredMBytes+"MiB of heap for all source files.");
+        // Perform heuristics to see how many cores we can use,
+        // or if we have to the work serially in smaller chunks.
+        if (numMBytes < numRequiredMBytes) {
+            // Ouch, cannot fit even a single compile into the heap.
+            // Split it up into several serial chunks.
+            concurrentCompiles = false;
+            // Limit the number of sources for each compile to 500.
+            if (numSources < 500) {
+                numCompiles = 1;
+                sourcesPerCompile = numSources;
+                Log.debug("Compiling as a single source code chunk to stay within heap size limitations!");
+            } else if (sourcesPerCompile > 500) {
+                // This number is very low, and tuned to dealing with the OpenJDK
+                // where the source is >very< circular! In normal application,
+                // with less circularity the number could perhaps be increased.
+                numCompiles = numSources / 500;
+                sourcesPerCompile = numSources/numCompiles;
+                Log.debug("Compiling source as "+numCompiles+" code chunks serially to stay within heap size limitations!");
+            }
+        } else {
+            if (numCompiles > 1) {
+                // Ok, we can fit at least one full compilation on the heap.
+                float usagePerCompile = (float)numRequiredMBytes / ((float)numCompiles * (float)0.7);
+                int usage = (int)(usagePerCompile * (float)numCompiles);
+                Log.debug("Heuristics say that for "+numCompiles+" concurrent compiles we need "+usage+"MiB");
+                if (usage > numMBytes) {
+                    // Ouch it does not fit. Reduce to a single chunk.
+                    numCompiles = 1;
+                    sourcesPerCompile = numSources;
+                    // What if the relationship betweem number of compile_chunks and num_required_mbytes
+                    // is not linear? Then perhaps 2 chunks would fit where 3 does not. Well, this is
+                    // something to experiment upon in the future.
+                    Log.debug("Limiting compile to a single thread to stay within heap size limitations!");
+                }
+            }
+        }
+
+        Log.debug("Compiling sources in "+numCompiles+" chunk(s)");
+
+        // Create the chunks to be compiled.
+        final CompileChunk[] compileChunks = createCompileChunks(pkgSrcs, oldPackageDependents,
+                numCompiles, sourcesPerCompile);
+
+        if (Log.isDebugging()) {
+            int cn = 1;
+            for (CompileChunk cc : compileChunks) {
+                Log.debug("Chunk "+cn+" for "+id+" ---------------");
+                cn++;
+                for (URI u : cc.srcs) {
+                    Log.debug(""+u);
+                }
+            }
+        }
+
+        // The return values for each chunked compile.
+        final int[] rn = new int[numCompiles];
+        // The requets, might or might not run as a background thread.
+        final Thread[] requests  = new Thread[numCompiles];
+
+        final Set<URI>             fvisible_sources = visibleSources;
+        final Map<URI,Set<String>> fvisible_classes = visibleClasses;
+
+        long start = System.currentTimeMillis();
+
+        for (int i=0; i<numCompiles; ++i) {
+            final int ii = i;
+            final CompileChunk cc = compileChunks[i];
+
+            // Pass the num_cores and the id (appended with the chunk number) to the server.
+            final String cleanedServerSettings = psServerSettings+",poolsize="+numCores+",id="+id+"-"+ii;
+            final PrintStream fout = out;
+            final PrintStream ferr = err;
+
+            requests[ii] = new Thread() {
+                @Override
+                public void run() {
+                                        rn[ii] = JavacServer.useServer(cleanedServerSettings,
+                                                           Main.removeWrapperArgs(args),
+                                                               cc.srcs,
+                                                           fvisible_sources,
+                                                           fvisible_classes,
+                                                           packageArtifacts,
+                                                           packageDependencies,
+                                                           packagePubapis,
+                                                           null,
+                                                           fout, ferr);
+                }
+            };
+
+            if (cc.srcs.size() > 0) {
+                String numdeps = "";
+                if (cc.numDependents > 0) numdeps = "(with "+cc.numDependents+" dependents) ";
+                if (!incremental || cc.numPackages > 16) {
+                    String info = "("+cc.pkgFromTos+")";
+                    if (info.equals("( to )")) {
+                        info = "";
+                    }
+                    Log.info("Compiling "+cc.srcs.size()+" files "+numdeps+"in "+cc.numPackages+" packages "+info);
+                } else {
+                    Log.info("Compiling "+cc.pkgNames+numdeps);
+                }
+                if (concurrentCompiles) {
+                    requests[ii].start();
+                }
+                else {
+                    requests[ii].run();
+                    // If there was an error, then stop early when running single threaded.
+                    if (rn[i] != 0) {
+                        return false;
+                    }
+                }
+            }
+        }
+        if (concurrentCompiles) {
+            // If there are background threads for the concurrent compiles, then join them.
+            for (int i=0; i<numCompiles; ++i) {
+                try { requests[i].join(); } catch (InterruptedException e) { }
+            }
+        }
+
+        // Check the return values.
+        for (int i=0; i<numCompiles; ++i) {
+            if (compileChunks[i].srcs.size() > 0) {
+                if (rn[i] != 0) {
+                    rc = false;
+                }
+            }
+        }
+        long duration = System.currentTimeMillis() - start;
+        long minutes = duration/60000;
+        long seconds = (duration-minutes*60000)/1000;
+        Log.debug("Compilation of "+numSources+" source files took "+minutes+"m "+seconds+"s");
+
+        return rc;
+    }
+
+
+    /**
+     * Split up the sources into compile chunks. If old package dependents information
+     * is available, sort the order of the chunks into the most dependent first!
+     * (Typically that chunk contains the java.lang package.) In the future
+     * we could perhaps improve the heuristics to put the sources into even more sensible chunks.
+     * Now the package are simple sorted in alphabetical order and chunked, then the chunks
+     * are sorted on how dependent they are.
+     *
+     * @param pkgSrcs The sources to compile.
+     * @param oldPackageDependents Old package dependents, if non-empty, used to sort the chunks.
+     * @param numCompiles The number of chunks.
+     * @param sourcesPerCompile The number of sources per chunk.
+     * @return
+     */
+    CompileChunk[] createCompileChunks(Map<String,Set<URI>> pkgSrcs,
+                                 Map<String,Set<String>> oldPackageDependents,
+                                 int numCompiles,
+                                 int sourcesPerCompile) {
+
+        CompileChunk[] compileChunks = new CompileChunk[numCompiles];
+        for (int i=0; i<compileChunks.length; ++i) {
+            compileChunks[i] = new CompileChunk();
+        }
+
+        // Now go through the packages and spread out the source on the different chunks.
+        int ci = 0;
+        // Sort the packages
+        String[] packageNames = pkgSrcs.keySet().toArray(new String[0]);
+        Arrays.sort(packageNames);
+        String from = null;
+        for (String pkgName : packageNames) {
+            CompileChunk cc = compileChunks[ci];
+            Set<URI> s = pkgSrcs.get(pkgName);
+            if (cc.srcs.size()+s.size() > sourcesPerCompile && ci < numCompiles-1) {
+                from = null;
+                ci++;
+                cc = compileChunks[ci];
+            }
+            cc.numPackages++;
+            cc.srcs.addAll(s);
+
+            // Calculate nice package names to use as information when compiling.
+            String justPkgName = Util.justPackageName(pkgName);
+            // Fetch how many packages depend on this package from the old build state.
+            Set<String> ss = oldPackageDependents.get(pkgName);
+            if (ss != null) {
+                // Accumulate this information onto this chunk.
+                cc.numDependents += ss.size();
+            }
+            if (from == null || from.trim().equals("")) from = justPkgName;
+            cc.pkgNames.append(justPkgName+"("+s.size()+") ");
+            cc.pkgFromTos = from+" to "+justPkgName;
+        }
+        // If we are compiling serially, sort the chunks, so that the chunk (with the most dependents) (usually the chunk
+        // containing java.lang.Object, is to be compiled first!
+        // For concurrent compilation, this does not matter.
+        Arrays.sort(compileChunks);
+        return compileChunks;
+    }
+}