configurable max.simultaneous.builds option

java/compiler/impl/src/com/intellij/compiler/CompileServerManager.java

@@ -586,6 +586,7 @@ public class CompileServerManager implements ApplicationComponent{
     cmdLine.addParameter("-XX:ReservedCodeCacheSize=64m");
     cmdLine.addParameter("-Xmx" + Registry.intValue("compiler.server.heap.size") + "m");
     cmdLine.addParameter("-Djava.awt.headless=true");
+
     final String shouldGenerateIndex = System.getProperty(GlobalOptions.GENERATE_CLASSPATH_INDEX_OPTION);
     if (shouldGenerateIndex != null) {
       cmdLine.addParameter("-D"+ GlobalOptions.GENERATE_CLASSPATH_INDEX_OPTION +"=" + shouldGenerateIndex);
@@ -594,6 +595,12 @@ public class CompileServerManager implements ApplicationComponent{
     if (pingInterval > 0L) {
       cmdLine.addParameter("-D" + GlobalOptions.PING_INTERVAL_MS_OPTION + "=" + pingInterval);
     }
+
+    final String maxBuilds = Registry.stringValue("compiler.server.max.simultaneous.builds");
+    if (!StringUtil.isEmpty(maxBuilds)) {
+      cmdLine.addParameter("-D" + GlobalOptions.MAX_SIMULTANEOUS_BUILDS_OPTION + "=" + maxBuilds);
+    }
+
     final String additionalOptions = Registry.stringValue("compiler.server.vm.options");
     if (!StringUtil.isEmpty(additionalOptions)) {
       final StringTokenizer tokenizer = new StringTokenizer(additionalOptions, " ", false);

jps/jps-builders/src/org/jetbrains/jps/api/GlobalOptions.java

@@ -10,4 +10,5 @@ public interface GlobalOptions {
   String HOSTNAME_OPTION = "localhost.name";
   String PING_INTERVAL_MS_OPTION = "server.ping.interval";
   String GENERATE_CLASSPATH_INDEX_OPTION = "generate.classpath.index";
+  String MAX_SIMULTANEOUS_BUILDS_OPTION = "max.simultaneous.builds";
 }

jps/jps-builders/src/org/jetbrains/jps/server/Server.java

@@ -35,11 +35,32 @@ import java.util.concurrent.TimeUnit;
  */
 public class Server {
   public static final int DEFAULT_SERVER_PORT = 7777;
-  private static final int MAX_SIMULTANEOUS_BUILD_SESSIONS = Math.max(2, Runtime.getRuntime().availableProcessors());
   public static final String SERVER_SUCCESS_START_MESSAGE = "Compile Server started successfully. Listening on port: ";
   public static final String SERVER_ERROR_START_MESSAGE = "Error starting Compile Server: ";
   private static final String LOG_FILE_NAME = "log.xml";
-  private static final long PING_INTERVAL = Long.parseLong(System.getProperty(GlobalOptions.PING_INTERVAL_MS_OPTION, "-1")); 
+
+  private static final long PING_INTERVAL;
+  private static final int MAX_SIMULTANEOUS_BUILD_SESSIONS;
+  static {
+    long ping = -1L;
+    try {
+      ping = Long.parseLong(System.getProperty(GlobalOptions.PING_INTERVAL_MS_OPTION, "-1"));
+    }
+    catch (NumberFormatException ignored) {
+    }
+    PING_INTERVAL = ping;
+
+    int builds = 1;
+    try {
+      builds = Math.min(
+        Integer.parseInt(System.getProperty(GlobalOptions.MAX_SIMULTANEOUS_BUILDS_OPTION, "1")),
+        Runtime.getRuntime().availableProcessors()
+      );
+    }
+    catch (NumberFormatException ignored) {
+    }
+    MAX_SIMULTANEOUS_BUILD_SESSIONS = builds;
+  }
 
   private final ChannelGroup myAllOpenChannels = new DefaultChannelGroup("compile-server");
   private final ChannelFactory myChannelFactory;

jps/jps-builders/src/org/jetbrains/jps/server/ServerState.java

@@ -165,8 +165,6 @@ class ServerState {
       pd.incUsageCounter();
     }
 
-    final Project project = pd.project;
-
     try {
       final CompileScope compileScope = createCompilationScope(buildType, pd, modules, artifacts, paths);
       final IncProjectBuilder builder = new IncProjectBuilder(pd, BuilderRegistry.getInstance(), builderParams, cs);

platform/platform-resources-en/src/misc/registry.properties

@@ -136,6 +136,9 @@ compiler.server.enabled.description=Enable out-of-process compilation
 compiler.server.heap.size=300
 compiler.server.heap.size.description=Heap size value in MB for the compile server process
 
+compiler.server.max.simultaneous.builds=1
+compiler.server.max.simultaneous.builds.description=The max number of simultaneous build sessions. Increasing this value may require larger server heap size
+
 compiler.server.vm.options=-ea
 compiler.server.vm.options.description=Additional options for compile server's VM