fix #129: simplify support for multiple node processes

src/config/iisnode_schema.xml

@@ -29,7 +29,7 @@ Details at http://learn.iis.net/page.aspx/241/configuration-extensibility/
   <sectionSchema name="system.webServer/iisnode">
     <attribute name="node_env" type="string" expanded="true" defaultValue="%node_env%"/>
     <attribute name="asyncCompletionThreadCount" type="uint" defaultValue="0"/>
-    <attribute name="maxProcessCountPerApplication" type="uint" defaultValue="4"/>
+    <attribute name="nodeProcessCountPerApplication" type="uint" defaultValue="1"/>
     <attribute name="nodeProcessCommandLine" type="string" expanded="true" defaultValue="&quot;%programfiles%\nodejs\node.exe&quot;"/>
     <attribute name="maxConcurrentRequestsPerProcess" type="uint" allowInfitnite="true" defaultValue="1024"/>
     <attribute name="maxNamedPipeConnectionRetry" type="uint" defaultValue="3"/>

src/config/iisnode_schema_x64.xml

@@ -29,7 +29,7 @@ Details at http://learn.iis.net/page.aspx/241/configuration-extensibility/
   <sectionSchema name="system.webServer/iisnode">
     <attribute name="node_env" type="string" expanded="true" defaultValue="%node_env%"/>
     <attribute name="asyncCompletionThreadCount" type="uint" defaultValue="0"/>
-    <attribute name="maxProcessCountPerApplication" type="uint" defaultValue="4"/>
+    <attribute name="nodeProcessCountPerApplication" type="uint" defaultValue="1"/>
     <attribute name="nodeProcessCommandLine" type="string" expanded="true" defaultValue="&quot;%programfiles(x86)%\nodejs\node.exe&quot;"/>
     <attribute name="maxConcurrentRequestsPerProcess" type="uint" allowInfitnite="true" defaultValue="1024"/>
     <attribute name="maxNamedPipeConnectionRetry" type="uint" defaultValue="3"/>

src/iisnode/cmoduleconfiguration.cpp

@@ -434,7 +434,7 @@ HRESULT CModuleConfiguration::GetConfig(IHttpContext* context, CModuleConfigurat
 		
 		CheckError(GetConfigSection(context, &section));		
 		CheckError(GetDWORD(section, L"asyncCompletionThreadCount", &c->asyncCompletionThreadCount));
-		CheckError(GetDWORD(section, L"maxProcessCountPerApplication", &c->maxProcessCountPerApplication));
+		CheckError(GetDWORD(section, L"nodeProcessCountPerApplication", &c->nodeProcessCountPerApplication));
 		CheckError(GetDWORD(section, L"maxConcurrentRequestsPerProcess", &c->maxConcurrentRequestsPerProcess));
 		CheckError(GetDWORD(section, L"maxNamedPipeConnectionRetry", &c->maxNamedPipeConnectionRetry));
 		CheckError(GetDWORD(section, L"namedPipeConnectionRetryDelay", &c->namedPipeConnectionRetryDelay));
@@ -474,6 +474,16 @@ HRESULT CModuleConfiguration::GetConfig(IHttpContext* context, CModuleConfigurat
             GetSystemInfo(&info);
             c->asyncCompletionThreadCount = 0 == info.dwNumberOfProcessors ? 4 : info.dwNumberOfProcessors;
         }
+
+		if (0 == c->nodeProcessCountPerApplication)
+		{
+			// default number of node.exe processes to create per node.js application
+
+            SYSTEM_INFO info;
+
+            GetSystemInfo(&info);
+            c->nodeProcessCountPerApplication = 0 == info.dwNumberOfProcessors ? 1 : info.dwNumberOfProcessors;
+		}
 		
 		// CR: check for ERROR_ALREADY_ASSIGNED to detect a race in creation of this section 
 		// CR: refcounting may be needed if synchronous code paths proove too long (race with config changes)
@@ -521,9 +531,9 @@ DWORD CModuleConfiguration::GetAsyncCompletionThreadCount(IHttpContext* ctx)
 	GETCONFIG(asyncCompletionThreadCount)
 }
 
-DWORD CModuleConfiguration::GetMaxProcessCountPerApplication(IHttpContext* ctx)
+DWORD CModuleConfiguration::GetNodeProcessCountPerApplication(IHttpContext* ctx)
 {
-	GETCONFIG(maxProcessCountPerApplication)
+	GETCONFIG(nodeProcessCountPerApplication)
 }
 
 LPCTSTR CModuleConfiguration::GetNodeProcessCommandLine(IHttpContext* ctx)

src/iisnode/cmoduleconfiguration.h

@@ -8,7 +8,7 @@ class CModuleConfiguration : public IHttpStoredContext
 private:
 
 	DWORD asyncCompletionThreadCount;
-	DWORD maxProcessCountPerApplication;
+	DWORD nodeProcessCountPerApplication;
 	LPTSTR nodeProcessCommandLine;
 	DWORD maxConcurrentRequestsPerProcess;
 	DWORD maxNamedPipeConnectionRetry;
@@ -48,7 +48,7 @@ public:
 	static HRESULT Initialize(IHttpServer* server, HTTP_MODULE_ID moduleId);
 
 	static DWORD GetAsyncCompletionThreadCount(IHttpContext* ctx); 
-	static DWORD GetMaxProcessCountPerApplication(IHttpContext* ctx);
+	static DWORD GetNodeProcessCountPerApplication(IHttpContext* ctx);
 	static LPCTSTR GetNodeProcessCommandLine(IHttpContext* ctx); 
 	static DWORD GetMaxConcurrentRequestsPerProcess(IHttpContext* ctx);
 	static DWORD GetMaxNamedPipeConnectionRetry(IHttpContext* ctx);

src/iisnode/cnodeprocessmanager.cpp

@@ -1,16 +1,16 @@
 #include "precomp.h"
 
 CNodeProcessManager::CNodeProcessManager(CNodeApplication* application, IHttpContext* context)
-	: application(application), processes(NULL), processCount(0), currentProcess(0), isClosing(FALSE),
+	: application(application), processes(NULL), currentProcess(0), isClosing(FALSE),
 	refCount(1)
 {
 	if (this->GetApplication()->IsDebugMode())
 	{
-		this->maxProcessCount = 1;
+		this->processCount = 1;
 	}
 	else
 	{
-		this->maxProcessCount = CModuleConfiguration::GetMaxProcessCountPerApplication(context);
+		this->processCount = CModuleConfiguration::GetNodeProcessCountPerApplication(context);
 	}
 
 	// cache event provider since the application can be disposed prior to CNodeProcessManager
@@ -22,11 +22,19 @@ CNodeProcessManager::CNodeProcessManager(CNodeApplication* application, IHttpCon
 
 CNodeProcessManager::~CNodeProcessManager()
 {
-	if (NULL != processes)
+	this->Cleanup();
+}
+
+void CNodeProcessManager::Cleanup()
+{
+	if (NULL != this->processes)
 	{
 		for (int i = 0; i < this->processCount; i++)
 		{
-			delete this->processes[i];
+			if (this->processes[i])
+			{
+				delete this->processes[i];
+			}
 		}
 
 		delete[] this->processes;
@@ -43,74 +51,45 @@ HRESULT CNodeProcessManager::Initialize(IHttpContext* context)
 {
 	HRESULT hr;
 
-	ErrorIf(NULL == (this->processes = new CNodeProcess* [this->maxProcessCount]), ERROR_NOT_ENOUGH_MEMORY);
-	RtlZeroMemory(this->processes, this->maxProcessCount * sizeof(CNodeProcess*));
-	if (this->GetApplication()->IsDebuggee())
+	ErrorIf(NULL == (this->processes = new CNodeProcess* [this->processCount]), ERROR_NOT_ENOUGH_MEMORY);
+	RtlZeroMemory(this->processes, this->processCount * sizeof(CNodeProcess*));
+	for (int i = 0; i < this->processCount; i++)
 	{
-		// ensure the debugee process is started without activating message
-		// this is to make sure it is available for the debugger to connect to
-
-		CheckError(this->AddOneProcess(NULL, context));
+		CheckError(this->AddProcess(i, context));
 	}
 
 	return S_OK;
 Error:
 
-	if (NULL != this->processes)
-	{
-		delete [] this->processes;
-		this->processes = NULL;
-	}
+	this->Cleanup();
 
 	return hr;
 }
 
-HRESULT CNodeProcessManager::AddOneProcessCore(CNodeProcess** process, IHttpContext* context)
+HRESULT CNodeProcessManager::AddProcess(int ordinal, IHttpContext* context)
 {
 	HRESULT hr;
 
-	ErrorIf(this->processCount == this->maxProcessCount, ERROR_NOT_ENOUGH_QUOTA);
-	ErrorIf(NULL == (this->processes[this->processCount] = new CNodeProcess(this, context, this->processCount)), ERROR_NOT_ENOUGH_MEMORY);	
-	CheckError(this->processes[this->processCount]->Initialize(context));
-	if (NULL != process)
-	{
-		*process = this->processes[this->processCount];
-	}
-	this->processCount++;
+	ErrorIf(NULL != this->processes[ordinal], ERROR_INVALID_PARAMETER);
+	ErrorIf(NULL == (this->processes[ordinal] = new CNodeProcess(this, context, ordinal)), ERROR_NOT_ENOUGH_MEMORY);	
+	CheckError(this->processes[ordinal]->Initialize(context));
 
 	return S_OK;
 Error:
 
-	if (NULL != this->processes[this->processCount])
+	if (NULL != this->processes[ordinal])
 	{
-		delete this->processes[this->processCount];
-		this->processes[this->processCount] = NULL;
+		delete this->processes[ordinal];
+		this->processes[ordinal] = NULL;
 	}
 
 	return hr;
 }
 
-HRESULT CNodeProcessManager::AddOneProcess(CNodeProcess** process, IHttpContext* context)
-{
-	HRESULT hr;
-
-	if (NULL != process)
-	{
-		*process = NULL;
-	}
-
-	ErrorIf(this->processCount == this->maxProcessCount, ERROR_NOT_ENOUGH_QUOTA);
-	CheckError(this->AddOneProcessCore(process, context));
-
-	return S_OK;
-Error:
-
-	return hr;	
-}
-
 HRESULT CNodeProcessManager::Dispatch(CNodeHttpStoredContext* request)
 {
 	HRESULT hr;
+	unsigned int tmpProcess, processToUse;
 
 	CheckNull(request);
 
@@ -120,24 +99,48 @@ HRESULT CNodeProcessManager::Dispatch(CNodeHttpStoredContext* request)
 	{
 		ENTER_SRW_SHARED(this->srwlock)
 
-		if (!this->isClosing && this->TryRouteRequestToExistingProcess(request))
+		if (!this->isClosing)
 		{
-			request = NULL;
+			// employ a round robin routing logic to get a "ticket" to use a process with a specific ordinal number
+			
+			if (1 == this->processCount)
+			{
+				processToUse = 0;
+			}
+			else
+			{
+				do 
+				{
+					tmpProcess = this->currentProcess;
+					processToUse = (tmpProcess + 1) % this->processCount;
+				} while (tmpProcess != InterlockedCompareExchange(&this->currentProcess, processToUse, tmpProcess));
+			}
+
+			// try dispatch to that process
+
+			if (NULL != this->processes[processToUse]) 
+			{
+				CheckError(this->processes[processToUse]->AcceptRequest(request));
+				request = NULL;
+			}
 		}
 
 		LEAVE_SRW_SHARED(this->srwlock)
 
-		if (request && !this->isClosing)
+		if (NULL != request)
 		{
-			// existing processes were unable to accept this request; create a new process to handle it
+			// the process to dispatch to does not exist and must be recreated
 
 			ENTER_SRW_EXCLUSIVE(this->srwlock)
 
-			if (!this->isClosing && !this->TryRouteRequestToExistingProcess(request))
+			if (!this->isClosing)
 			{
-				CNodeProcess* newProcess = NULL;
-				CheckError(this->AddOneProcess(&newProcess, request->GetHttpContext()));
-				CheckError(newProcess->AcceptRequest(request));
+				if (NULL == this->processes[processToUse])
+				{
+					CheckError(this->AddProcess(processToUse, request->GetHttpContext()));
+				}
+
+				CheckError(this->processes[processToUse]->AcceptRequest(request));
 			}
 
 			LEAVE_SRW_EXCLUSIVE(this->srwlock)
@@ -162,29 +165,6 @@ Error:
 	return hr;
 }
 
-BOOL CNodeProcessManager::TryRouteRequestToExistingProcess(CNodeHttpStoredContext* context)
-{
-	if (this->processCount == 0)
-	{
-		return false;
-	}
-
-	DWORD i = this->currentProcess;
-
-	do {
-
-		if (S_OK == this->processes[i]->AcceptRequest(context))
-		{
-			return true;
-		}
-
-		i = (i + 1) % this->processCount;
-
-	} while (i != this->currentProcess);
-
-	return false;
-}
-
 HRESULT CNodeProcessManager::RecycleProcess(CNodeProcess* process)
 {
 	HRESULT hr;
@@ -221,13 +201,7 @@ HRESULT CNodeProcessManager::RecycleProcess(CNodeProcess* process)
 				return S_OK;
 			}
 
-			if (i < (this->processCount - 1))
-			{
-				memcpy(this->processes + i, this->processes + i + 1, sizeof (CNodeProcess*) * (this->processCount - i - 1));
-			}
-
-			this->processCount--;
-			this->currentProcess = 0;
+			this->processes[i] = NULL;
 
 			gracefulRecycle = TRUE;
 		}
@@ -277,7 +251,17 @@ HRESULT CNodeProcessManager::Recycle()
 
 	this->isClosing = TRUE;	
 
-	if (0 < this->processCount)
+	BOOL hasActiveProcess = FALSE;
+	for (int i = 0; i < this->processCount; i++)
+	{
+		if (this->processes[i])
+		{
+			hasActiveProcess = TRUE;
+			break;
+		}
+	}
+
+	if (hasActiveProcess)
 	{
 		// perform actual recycling on a diffrent thread to free up the file watcher thread
 
@@ -321,6 +305,7 @@ unsigned int CNodeProcessManager::GracefulShutdown(void* arg)
 	ProcessRecycleArgs* args = (ProcessRecycleArgs*)arg;
 	HRESULT hr;
 	HANDLE* drainHandles = NULL;
+	DWORD drainHandleCount = 0;
 
 	// drain active requests 
 
@@ -328,16 +313,20 @@ unsigned int CNodeProcessManager::GracefulShutdown(void* arg)
 	RtlZeroMemory(drainHandles, args->count * sizeof HANDLE);
 	for (int i = 0; i < args->count; i++)
 	{
-		drainHandles[i] = CreateEvent(NULL, TRUE, FALSE, NULL);
-		args->processes[i]->SignalWhenDrained(drainHandles[i]);
+		if (args->processes[i])
+		{
+			drainHandles[drainHandleCount] = CreateEvent(NULL, TRUE, FALSE, NULL);
+			args->processes[i]->SignalWhenDrained(drainHandles[drainHandleCount]);
+			drainHandleCount++;
+		}
 	}
 	
 	if (args->processManager->gracefulShutdownTimeout > 0)
 	{
-		WaitForMultipleObjects(args->count, drainHandles, TRUE, args->processManager->gracefulShutdownTimeout);
+		WaitForMultipleObjects(drainHandleCount, drainHandles, TRUE, args->processManager->gracefulShutdownTimeout);
 	}
 
-	for (int i = 0; i < args->count; i++)
+	for (int i = 0; i < drainHandleCount; i++)
 	{
 		CloseHandle(drainHandles[i]);
 	}

src/iisnode/cnodeprocessmanager.h

@@ -22,18 +22,16 @@ private:
 	CNodeApplication* application;
 	CNodeProcess** processes;
 	DWORD processCount;
-	DWORD maxProcessCount;
-	DWORD currentProcess;
+	unsigned int currentProcess;
 	SRWLOCK srwlock;
 	DWORD gracefulShutdownTimeout;
 	BOOL isClosing;
 	long refCount;
 	CNodeEventProvider* eventProvider;
 
-	HRESULT AddOneProcessCore(CNodeProcess** process, IHttpContext* context);
-	HRESULT AddOneProcess(CNodeProcess** process, IHttpContext* context);
-	BOOL TryRouteRequestToExistingProcess(CNodeHttpStoredContext* context);
+	HRESULT AddProcess(int ordinal, IHttpContext* context);
 	static unsigned int WINAPI GracefulShutdown(void* arg);
+	void Cleanup();
 
 public:
 

src/samples/configuration/readme.htm

@@ -54,12 +54,11 @@ console.log('Application started at location ' + process.env.PORT);</pre>
     * nodeProcessCommandLine - command line starting the node executable; in shared
       hosting environments this setting would typically be locked at the machine scope.
       
-    * maxProcessCountPerApplication - maximum number of node processes that IIS will start
-      per application to accomodate incresing request load
+    * nodeProcessCountPerApplication - number of node.exe processes that IIS will start per application;
+      setting this value to 0 results in creating one node.exe process per each processor on the machine
       
     * maxConcurrentRequestsPerProcess - maximum number of reqeusts one node process can 
-      handle at a time; if a request arrives while all existing node processes have reached their 
-      limit, a new node process is created to handle it (up to the limit of maxProcessCountPerApplication)
+      handle at a time
       
     * maxNamedPipeConnectionRetry - number of times IIS will retry to establish a named pipe connection with a
       node process in order to send a new HTTP request
@@ -87,7 +86,7 @@ console.log('Application started at location ' + process.env.PORT);</pre>
     
     * logDirectoryNameSuffix - suffix of the directory name that will store files with stdout and stderr captures; directly name is created
       by appending this suffix to the file name of the node.js application; individual log files are stored in that directory, one per node 
-      process (in files of the form x.txt, where x is between 0 and maxProcessCountPerApplication - 1); given a node.js application at
+      process (in files of the form x.txt, where x is between 0 and nodeProcessCountPerApplication - 1); given a node.js application at
       http://localhost/node/hello.js, log files would by default be stored at http://localhost/node/hello.js.logs/0.txt (thrugh 3.txt); 
       SECURITY NOTE: if log files contain sensitive information, this setting should be modified to contain enough entropy to be considered
       cryptographically secure; in most situations, a GUID is sufficient
@@ -119,7 +118,7 @@ console.log('Application started at location ' + process.env.PORT);</pre>
     
     &lt;iisnode      
       node_env="%node_env%"
-      maxProcessCountPerApplication="4"
+      nodeProcessCountPerApplication="1"
       maxConcurrentRequestsPerProcess="1024"
       maxNamedPipeConnectionRetry="3"
       namedPipeConnectionRetryDelay="2000"      

src/samples/configuration/web.config

@@ -20,12 +20,11 @@
     * nodeProcessCommandLine - command line starting the node executable; in shared
       hosting environments this setting would typically be locked at the machine scope.
       
-    * maxProcessCountPerApplication - maximum number of node processes that IIS will start
-      per application to accomodate incresing request load
+    * nodeProcessCountPerApplication - number of node.exe processes that IIS will start per application;
+      setting this value to 0 results in creating one node.exe process per each processor on the machine
       
     * maxConcurrentRequestsPerProcess - maximum number of reqeusts one node process can 
-      handle at a time; if a request arrives while all existing node processes have reached their 
-      limit, a new node process is created to handle it (up to the limit of maxProcessCountPerApplication)
+      handle at a time
       
     * maxNamedPipeConnectionRetry - number of times IIS will retry to establish a named pipe connection with a
       node process in order to send a new HTTP request
@@ -53,7 +52,7 @@
     
     * logDirectoryNameSuffix - suffix of the directory name that will store files with stdout and stderr captures; directly name is created
       by appending this suffix to the file name of the node.js application; individual log files are stored in that directory, one per node 
-      process (in files of the form x.txt, where x is between 0 and maxProcessCountPerApplication - 1); given a node.js application at
+      process (in files of the form x.txt, where x is between 0 and nodeProcessCountPerApplication - 1); given a node.js application at
       http://localhost/node/hello.js, log files would by default be stored at http://localhost/node/hello.js.logs/0.txt (thrugh 3.txt); 
       SECURITY NOTE: if log files contain sensitive information, this setting should be modified to contain enough entropy to be considered
       cryptographically secure; in most situations, a GUID is sufficient
@@ -85,7 +84,7 @@
     
     <iisnode      
       node_env="%node_env%"
-      maxProcessCountPerApplication="4"
+      nodeProcessCountPerApplication="1"
       maxConcurrentRequestsPerProcess="1024"
       maxNamedPipeConnectionRetry="3"
       namedPipeConnectionRetryDelay="2000"      

test/functional/tests/114_roundrobin.js

@@ -0,0 +1,12 @@
+/*
+Four consecutive requests are dispatched to two node.exe processes following a round robin algorithm
+*/
+
+var iisnodeassert = require("iisnodeassert");
+
+iisnodeassert.sequence([
+    iisnodeassert.get(10000, "/114_roundrobin/hello.js", 200, "Hello, world 1"),
+    iisnodeassert.get(2000, "/114_roundrobin/hello.js", 200, "Hello, world 1"),
+    iisnodeassert.get(2000, "/114_roundrobin/hello.js", 200, "Hello, world 2"),
+    iisnodeassert.get(2000, "/114_roundrobin/hello.js", 200, "Hello, world 2")
+]);

test/functional/www/114_roundrobin/hello.js

@@ -0,0 +1,8 @@
+var http = require('http');
+
+var n = 1;
+
+http.createServer(function (req, res) {
+    res.writeHead(200, {'Content-Type': 'text/html'});
+    res.end('Hello, world ' + n++);
+}).listen(process.env.PORT);  

test/functional/www/114_roundrobin/web.config

@@ -0,0 +1,8 @@
+<configuration>
+  <system.webServer>
+    <handlers>
+      <add name="iisnode" path="hello.js" verb="*" modules="iisnode" />
+    </handlers>
+    <iisnode nodeProcessCountPerApplication="2" />
+  </system.webServer>
+</configuration>

test/performance/www/cluster/server.js

@@ -12,7 +12,7 @@ else {
     var cluster = require('cluster');
 
     if (cluster.isMaster) {
-        for (var i = 0; i < 3; i++) {
+        for (var i = 0; i < 4; i++) {
             cluster.fork();
         }
 

test/performance/www/cluster/web.config

@@ -11,7 +11,7 @@
       loggingEnabled="false" 
       debuggingEnabled="false" 
       devErrorsEnabled="false" 
-      maxProcessCountPerApplication="3" 
+      nodeProcessCountPerApplication="4" 
       maxConcurrentRequestsPerProcess="999999999" 
       maxNamedPipeConnectionRetry="10" 
     />

test/performance/www/default/web.config

@@ -11,7 +11,7 @@
       loggingEnabled="false" 
       debuggingEnabled="false" 
       devErrorsEnabled="false" 
-      maxProcessCountPerApplication="1" 
+      nodeProcessCountPerApplication="1" 
       maxConcurrentRequestsPerProcess="999999999" 
       maxNamedPipeConnectionRetry="10" />
     <urlCompression doStaticCompression="false" doDynamicCompression="false" />