0
@@ -87,6 +87,10 @@ information:
0
 - max: integer
0
   The maximum number of AppContainer objects that may exist in 'apps'.
0
 
0
+- max_per_app: integer
0
+  The maximum number of concurrent AppContainer objects a single 
0
+  application may spawn.
0
+
0
 - count: integer
0
   The current number of AppContainer objects in 'apps'.
0
   Since 'max' can be set dynamically during the life time of an application
0
@@ -115,6 +119,15 @@ information:
0
      for all keys app_root in restart_times:
0
         apps.has_key(app_root)
0
 
0
+- app_instance_count: map[string => unsigned int]
0
+  Maps an application root to the number of spawned applications.
0
+
0
+  Invariant:
0
+     app_instance_count.keys == apps.keys
0
+     for all keys app_root in app_instance_count:
0
+        app_instance_count[app_root] < count
0
+     (sum of all values in app_instance_count) == count.
0
+
0
 
0
 == Algorithm in pseudo code
0
 
0
@@ -142,6 +155,7 @@ function get(app_root):
0
           list.remove(container.iterator)
0
           if list.empty():
0
             apps.remove(app_root)
0
+					app_instance_count.remove(app_root)
0
           count--
0
           active--
0
 
0
@@ -155,25 +169,33 @@ function spawn_or_use_existing(app_root):
0
   
0
   if (list != nil) and (needs_restart(app_root)):
0
     for all container in list:
0
-				if container.sessions == 0:
0
-					inactive_apps.remove(container.ia_iterator)
0
-				else:
0
-					active--
0
-				list.remove(container.iterator)
0
-				count--
0
-			apps.remove(app_root)
0
-			list = nil
0
-			Tell spawn server to reload code for app_root.
0
+			if container.sessions == 0:
0
+				inactive_apps.remove(container.ia_iterator)
0
+			else:
0
+				active--
0
+			list.remove(container.iterator)
0
+			count--
0
+		apps.remove(app_root)
0
+		app_instance_count.remove(app_root)
0
+		list = nil
0
+		Tell spawn server to reload code for app_root.
0
   
0
   if list != nil:
0
     # There are apps for this app root.
0
-		if (list.front.sessions == 0) or (count >= max):
0
+		if (list.front.sessions == 0) or (count >= max) or (
0
+		   (max_per_app != 0) and (app_instance_count[app_root] >= max_per_app)
0
+		   ):
0
       # There is an inactive app, so we use it.
0
       #  -OR-
0
-			# All apps are active, and the pool is full. We're not
0
-			# allowed to spawn a new app, so we try to connect to
0
-			# an existing one. Our connection request will be put
0
-			# into that app's connection queue.
0
+			# All apps are active, and the pool is full. 
0
+			#  -OR-
0
+			# All apps are active and the number of max instances
0
+			# spawned for this rails application has been reached.
0
+			#
0
+			# We're not allowed to spawn a new app, so if there are
0
+			# no inactive apps, we try to connect to an existing one.
0
+			# Our connection request will be put into that app's
0
+			# connection queue.
0
       container = list.front
0
       list.move_to_back(container.iterator)
0
       if container.sessions == 0:
0
@@ -183,17 +205,19 @@ function spawn_or_use_existing(app_root):
0
       # All apps are active, but the pool hasn't reached its
0
       # maximum yet. So we spawn a new app.
0
       container = new AppContainer
0
-			# TODO: we should unlock the mutex during spawning,
0
-			# and add some kind of timeout check.
0
+			# TODO: we should add some kind of timeout check for spawning.
0
       container.app = spawn(app_root)
0
       container.sessions = 0;
0
       iterator = list.add_to_back(container)
0
       container.iterator = iterator
0
+			app_instance_count[app_root]++
0
       count++
0
       active++
0
   else:
0
     # There are no apps for this app root.
0
-		wait until active < max
0
+		wait until
0
+		  (active < max) and
0
+		  (max_per_app == 0 or app_instance_count[app_root] < max_per_app)
0
     if count == max:
0
       # Here we are in a though situation. There are several
0
       # apps which are inactive, and none of them have
0
@@ -212,16 +236,21 @@ function spawn_or_use_existing(app_root):
0
       if list.empty():
0
         apps.remove(container.app.app_root)
0
         restart_file_times.remove(container.app.app_root)
0
+				app_instance_count.remove(container.app.app_root)
0
+			else:
0
+				app_instance_count[container.app.app_root]--
0
       count--
0
     container = new AppContainer
0
-		# TODO: we should unlock the mutex during spawning,
0
-		# and add some kind of timeout check.
0
+		# TODO: we should add some kind of timeout check for spawning.
0
     container.app = spawn(app_root)
0
-		container.sessions = 0;
0
+		container.sessions = 0
0
     list = apps[app_root]
0
     if list == nil:
0
       list = new list
0
       apps[app_root] = list
0
+			app_instance_count[app_root] = 1
0
+		else:
0
+			app_instance_count[app_root]++
0
     iterator = list.add_to_back(container)
0
     container.iterator = iterator
0
     count++
0
@@ -283,8 +312,10 @@ thread cleaner:
0
         if now - container.last_used > MAX_IDLE_TIME:
0
           app_list.remove(container.iterator)
0
           inactive_apps.remove(iterator for container)
0
+					app_instance_count[app.app_root]--
0
           count--
0
         if app_list.empty():
0
           apps.remove(app.app_root)
0
+					app_instance_count.remove(app.app_root)
0
           restart_file_times.remove(app.app_root)
0
 

0
@@ -159,6 +159,15 @@ public:
0
   virtual unsigned int getCount() const = 0;
0
   
0
   /**
0
+	 * Set a hard limit on the number of application instances that a single application
0
+	 * may spawn in this ApplicationPool. The exact behavior depends on the used algorithm, 
0
+	 * and is not specified by these API docs.
0
+	 *
0
+	 * It is allowed to set a limit lower than the current number of spawned applications.
0
+	 */
0
+	virtual void setMaxPerApp(unsigned int max) = 0;
0
+	
0
+	/**
0
    * Get the process ID of the spawn server that is used.
0
    *
0
    * This method exposes an implementation detail. It is used by unit tests to verify

0
@@ -265,6 +265,12 @@ private:
0
       return atoi(args[0].c_str());
0
     }
0
     
0
+		virtual void setMaxPerApp(unsigned int max) {
0
+			MessageChannel channel(data->server);
0
+			mutex::scoped_lock l(data->lock);
0
+			channel.write("setMaxPerApp", toString(max).c_str(), NULL);
0
+		}
0
+		
0
     virtual pid_t getSpawnServerPid() const {
0
       MessageChannel channel(data->server);
0
       mutex::scoped_lock l(data->lock);

0
@@ -256,6 +256,10 @@ private:
0
     channel.write(toString(server.pool.getCount()).c_str(), NULL);
0
   }
0
   
0
+	void processSetMaxPerApp(unsigned int maxPerApp) {
0
+		server.pool.setMaxPerApp(maxPerApp);
0
+	}
0
+	
0
   void processGetSpawnServerPid(const vector<string> &args) {
0
     channel.write(toString(server.pool.getSpawnServerPid()).c_str(), NULL);
0
   }
0
@@ -307,6 +311,8 @@ private:
0
           processGetActive(args);
0
         } else if (args[0] == "getCount" && args.size() == 1) {
0
           processGetCount(args);
0
+				} else if (args[0] == "setMaxPerApp" && args.size() == 2) {
0
+					processSetMaxPerApp(atoi(args[1]));
0
         } else if (args[0] == "getSpawnServerPid" && args.size() == 1) {
0
           processGetSpawnServerPid(args);
0
         } else {

0
@@ -26,6 +26,7 @@ using namespace Passenger;
0
 extern "C" module AP_MODULE_DECLARE_DATA passenger_module;
0
 
0
 #define DEFAULT_MAX_POOL_SIZE 20
0
+#define DEFAULT_MAX_INSTANCES_PER_APP 0
0
 #define DEFAULT_POOL_IDLE_TIME 120
0
 
0
 
0
@@ -86,6 +87,8 @@ passenger_config_create_server(apr_pool_t *p, server_rec *s) {
0
   config->root = NULL;
0
   config->maxPoolSize = DEFAULT_MAX_POOL_SIZE;
0
   config->maxPoolSizeSpecified = false;
0
+	config->maxInstancesPerApp = DEFAULT_MAX_INSTANCES_PER_APP;
0
+	config->maxInstancesPerAppSpecified = false;
0
   config->poolIdleTime = DEFAULT_POOL_IDLE_TIME;
0
   config->poolIdleTimeSpecified = false;
0
   config->userSwitching = true;
0
@@ -104,6 +107,8 @@ passenger_config_merge_server(apr_pool_t *p, void *basev, void *addv) {
0
   config->root = (add->root == NULL) ? base->root : add->root;
0
   config->maxPoolSize = (add->maxPoolSizeSpecified) ? base->maxPoolSize : add->maxPoolSize;
0
   config->maxPoolSizeSpecified = base->maxPoolSizeSpecified || add->maxPoolSizeSpecified;
0
+	config->maxInstancesPerApp = (add->maxInstancesPerAppSpecified) ? base->maxInstancesPerApp : add->maxInstancesPerApp;
0
+	config->maxInstancesPerAppSpecified = base->maxInstancesPerAppSpecified || add->maxInstancesPerAppSpecified;
0
   config->poolIdleTime = (add->poolIdleTime) ? base->poolIdleTime : add->poolIdleTime;
0
   config->poolIdleTimeSpecified = base->poolIdleTimeSpecified || add->poolIdleTimeSpecified;
0
   config->userSwitching = (add->userSwitchingSpecified) ? add->userSwitching : base->userSwitching;
0
@@ -123,6 +128,8 @@ passenger_config_merge_all_servers(apr_pool_t *pool, server_rec *main_server) {
0
     final->root = (final->root != NULL) ? final->root : config->root;
0
     final->maxPoolSize = (final->maxPoolSizeSpecified) ? final->maxPoolSize : config->maxPoolSize;
0
     final->maxPoolSizeSpecified = final->maxPoolSizeSpecified || config->maxPoolSizeSpecified;
0
+		final->maxInstancesPerApp = (final->maxInstancesPerAppSpecified) ? final->maxInstancesPerApp : config->maxInstancesPerApp;
0
+		final->maxInstancesPerAppSpecified = final->maxInstancesPerAppSpecified || config->maxInstancesPerAppSpecified;
0
     final->poolIdleTime = (final->poolIdleTimeSpecified) ? final->poolIdleTime : config->poolIdleTime;
0
     final->poolIdleTimeSpecified = final->poolIdleTimeSpecified || config->poolIdleTimeSpecified;
0
     final->userSwitching = (config->userSwitchingSpecified) ? config->userSwitching : final->userSwitching;
0
@@ -212,6 +219,23 @@ cmd_rails_max_pool_size(cmd_parms *cmd, void *pcfg, const char *arg) {
0
 }
0
 
0
 static const char *
0
+cmd_rails_max_instances_per_app(cmd_parms *cmd, void *pcfg, const char *arg) {
0
+	ServerConfig *config = (ServerConfig *) ap_get_module_config(
0
+		cmd->server->module_config, &passenger_module);
0
+	char *end;
0
+	long int result;
0
+	
0
+	result = strtol(arg, &end, 10);
0
+	if (*end != '\0') {
0
+		return "Invalid number specified for RailsMaxInstancesPerApp.";
0
+	} else {
0
+		config->maxInstancesPerApp = (unsigned int) result;
0
+		config->maxInstancesPerAppSpecified = true;
0
+		return NULL;
0
+	}
0
+}
0
+
0
+static const char *
0
 cmd_rails_pool_idle_time(cmd_parms *cmd, void *pcfg, const char *arg) {
0
   ServerConfig *config = (ServerConfig *) ap_get_module_config(
0
     cmd->server->module_config, &passenger_module);
0
@@ -301,6 +325,11 @@ const command_rec passenger_commands[] = {
0
     NULL,
0
     RSRC_CONF,
0
     "The maximum number of simultaneously alive Rails application instances."),
0
+	AP_INIT_TAKE1("RailsMaxInstancesPerApp",
0
+		(Take1Func) cmd_rails_max_instances_per_app,
0
+		NULL,
0
+		RSRC_CONF,
0
+		"The maximum number of simultaneously alive Rails application instances a single application may occupy."),
0
   AP_INIT_TAKE1("RailsPoolIdleTime",
0
     (Take1Func) cmd_rails_pool_idle_time,
0
     NULL,

0
@@ -76,6 +76,14 @@
0
        * this server config. */
0
       bool maxPoolSizeSpecified;
0
       
0
+			/** The maximum number of simultaneously alive Rails application
0
+			 * that a single Rails application may occupy. */
0
+			unsigned int maxInstancesPerApp;
0
+			
0
+			/** Whether the maxInstancesPerApp option was explicitly specified in
0
+			 * this server config. */
0
+			bool maxInstancesPerAppSpecified;
0
+			
0
       /** The maximum number of seconds that a Rails application may be
0
        * idle before it gets terminated. */
0
       unsigned int poolIdleTime;

0
@@ -364,6 +364,7 @@ public:
0
       applicationPool = applicationPoolServer->connect();
0
       applicationPoolServer->detach();
0
       applicationPool->setMax(config->maxPoolSize);
0
+			applicationPool->setMaxPerApp(config->maxInstancesPerApp);
0
       applicationPool->setMaxIdleTime(config->poolIdleTime);
0
     } catch (const exception &e) {
0
       fprintf(stderr, "*** Cannot initialize Passenger: %s\n", e.what());

0
@@ -90,6 +90,7 @@ class StandardApplicationPool: public ApplicationPool {
0
 private:
0
   static const int DEFAULT_MAX_IDLE_TIME = 120;
0
   static const int DEFAULT_MAX_POOL_SIZE = 20;
0
+	static const int DEFAULT_MAX_INSTANCES_PER_APP = 0;
0
   static const int CLEANER_THREAD_STACK_SIZE = 1024 * 128;
0
 
0
   friend class ApplicationPoolServer;
0
@@ -116,8 +117,10 @@ private:
0
     unsigned int max;
0
     unsigned int count;
0
     unsigned int active;
0
+		unsigned int maxPerApp;
0
     AppContainerList inactiveApps;
0
     map<string, time_t> restartFileTimes;
0
+		map<string, unsigned int> appInstanceCount;
0
   };
0
   
0
   typedef shared_ptr<SharedData> SharedDataPtr;
0
@@ -179,8 +182,10 @@ private:
0
   unsigned int &max;
0
   unsigned int &count;
0
   unsigned int &active;
0
+	unsigned int &maxPerApp;
0
   AppContainerList &inactiveApps;
0
   map<string, time_t> &restartFileTimes;
0
+	map<string, unsigned int> &appInstanceCount;
0
   
0
   bool needsRestart(const string &appRoot) {
0
     string restartFile(appRoot);
0
@@ -247,10 +252,13 @@ private:
0
           inactiveApps.erase(it);
0
           it = prev;
0
           
0
+					appInstanceCount[app->getAppRoot()]--;
0
+					
0
           count--;
0
         }
0
         if (appList->empty()) {
0
           apps.erase(app->getAppRoot());
0
+					appInstanceCount.erase(app->getAppRoot());
0
           data->restartFileTimes.erase(app->getAppRoot());
0
         }
0
       }
0
@@ -300,6 +308,7 @@ private:
0
           count--;
0
         }
0
         apps.erase(appRoot);
0
+				appInstanceCount.erase(appRoot);
0
         spawnManager.reload(appRoot);
0
         it = apps.end();
0
       }
0
@@ -307,7 +316,8 @@ private:
0
       if (it != apps.end()) {
0
         list = it->second.get();
0
     
0
-				if (list->front()->sessions == 0 || count >= max) {
0
+				if (list->front()->sessions == 0 || count >= max
0
+				 || ( maxPerApp != 0 && appInstanceCount[appRoot] >= maxPerApp )) {
0
           container = list->front();
0
           list->pop_front();
0
           list->push_back(container);
0
@@ -326,12 +336,16 @@ private:
0
           list->push_back(container);
0
           container->iterator = list->end();
0
           container->iterator--;
0
+					appInstanceCount[appRoot]++;
0
           count++;
0
           active++;
0
           activeOrMaxChanged.notify_all();
0
         }
0
       } else {
0
-				while (active >= max) {
0
+				while (!(
0
+					active < max &&
0
+					(maxPerApp == 0 || appInstanceCount[appRoot] < maxPerApp)
0
+				)) {
0
           activeOrMaxChanged.wait(l);
0
         }
0
         if (count == max) {
0
@@ -342,6 +356,9 @@ private:
0
           if (list->empty()) {
0
             apps.erase(container->app->getAppRoot());
0
             restartFileTimes.erase(container->app->getAppRoot());
0
+						appInstanceCount.erase(container->app->getAppRoot());
0
+					} else {
0
+						appInstanceCount[container->app->getAppRoot()]--;
0
           }
0
           count--;
0
         }
0
@@ -353,8 +370,10 @@ private:
0
         if (it == apps.end()) {
0
           list = new AppContainerList();
0
           apps[appRoot] = ptr(list);
0
+					appInstanceCount[appRoot] = 1;
0
         } else {
0
           list = it->second.get();
0
+					appInstanceCount[appRoot]++;
0
         }
0
         list->push_back(container);
0
         container->iterator = list->end();
0
@@ -420,14 +439,17 @@ public:
0
     max(data->max),
0
     count(data->count),
0
     active(data->active),
0
+		maxPerApp(data->maxPerApp),
0
     inactiveApps(data->inactiveApps),
0
-		restartFileTimes(data->restartFileTimes)
0
+		restartFileTimes(data->restartFileTimes),
0
+		appInstanceCount(data->appInstanceCount)
0
   {
0
     detached = false;
0
     done = false;
0
     max = DEFAULT_MAX_POOL_SIZE;
0
     count = 0;
0
     active = 0;
0
+		maxPerApp = DEFAULT_MAX_INSTANCES_PER_APP;
0
     maxIdleTime = DEFAULT_MAX_IDLE_TIME;
0
     cleanerThread = new thread(
0
       bind(&StandardApplicationPool::cleanerThreadMainLoop, this),
0
@@ -491,6 +513,7 @@ public:
0
           if (list.empty()) {
0
             apps.erase(appRoot);
0
           }
0
+					appInstanceCount.erase(appRoot);
0
           count--;
0
           active--;
0
         }
0
@@ -505,6 +528,7 @@ public:
0
     apps.clear();
0
     inactiveApps.clear();
0
     restartFileTimes.clear();
0
+		appInstanceCount.clear();
0
     count = 0;
0
     active = 0;
0
   }
0
@@ -529,6 +553,12 @@ public:
0
     return count;
0
   }
0
   
0
+	virtual void setMaxPerApp(unsigned int maxPerApp) {
0
+		mutex::scoped_lock l(lock);
0
+		this->maxPerApp = maxPerApp;
0
+		activeOrMaxChanged.notify_all();
0
+	}
0
+	
0
   virtual pid_t getSpawnServerPid() const {
0
     return spawnManager.getServerPid();
0
   }