Servers shouldn't die on EMFILE

lib/net.js

@@ -42,6 +42,7 @@ var getsockname = binding.getsockname;
 var errnoException = binding.errnoException;
 var EINPROGRESS = binding.EINPROGRESS;
 var ENOENT      = binding.ENOENT;
+var EMFILE      = binding.EMFILE;
 var END_OF_FILE = 42;
 
 
@@ -238,6 +239,29 @@ var ioWatchers = new FreeList("iowatcher", 100, function () {
 });
 
 
+// waitingForFDs stores servers which have experienced EMFILE.
+// When a file descriptor becomes available through closeFD()
+// a server from waitingForFDs is started.
+
+var waitingForFDs = [];
+
+function closeFD(fd) {
+  close(fd);
+
+  // Try to recover from EMFILE
+
+  var server, serverFD;
+  while (server = waitingForFDs.shift()) {
+    serverFD = parseInt(server.fd);
+    if (serverFD && serverFD > 0) {
+      server.watcher.set(serverFD, true, false);
+      server.watcher.start();
+      return;
+    }
+  }
+}
+
+
 // Allocated on demand.
 var pool = null;
 function allocNewPool () {
@@ -675,7 +699,7 @@ Stream.prototype.destroy = function (exception) {
 
   // FIXME Bug when this.fd == 0
   if (typeof this.fd == 'number') {
-    close(this.fd);
+    closeFD(this.fd);
     this.fd = null;
     process.nextTick(function () {
       if (exception) self.emit('error', exception);
@@ -733,7 +757,16 @@ function Server (listener) {
   self.watcher.host = self;
   self.watcher.callback = function () {
     while (self.fd) {
-      var peerInfo = accept(self.fd);
+      try {
+        var peerInfo = accept(self.fd);
+      } catch (e) {
+        if (e.errno == EMFILE) {
+          waitingForFDs.push(self);
+          self.watcher.stop();
+          return;
+        }
+        throw e;
+      }
       if (!peerInfo) return;
 
       var s = new Stream(peerInfo.fd);
@@ -846,7 +879,7 @@ Server.prototype.close = function () {
 
   self.watcher.stop();
 
-  close(self.fd);
+  closeFD(self.fd);
   self.fd = null;
 
   if (self.type === "unix") {

src/node_net2.cc

@@ -1294,6 +1294,7 @@ void InitNet2(Handle<Object> target) {
   NODE_SET_METHOD(target, "errnoException", CreateErrnoException);
 
   target->Set(String::NewSymbol("ENOENT"), Integer::New(ENOENT));
+  target->Set(String::NewSymbol("EMFILE"), Integer::New(EMFILE));
   target->Set(String::NewSymbol("EINPROGRESS"), Integer::New(EINPROGRESS));
   target->Set(String::NewSymbol("EINTR"), Integer::New(EINTR));
   target->Set(String::NewSymbol("EACCES"), Integer::New(EACCES));