http: add agent.maxFreeSockets option

lib/_http_agent.js

@@ -59,6 +59,7 @@ function Agent(options) {
   self.keepAliveMsecs = self.options.keepAliveMsecs || 1000;
   self.keepAlive = self.options.keepAlive || false;
   self.maxSockets = self.options.maxSockets || Agent.defaultMaxSockets;
+  self.maxFreeSockets = self.options.maxFreeSockets || 256;
 
   self.on('free', function(socket, options) {
     var name = self.getName(options);
@@ -80,11 +81,13 @@ function Agent(options) {
           !socket.destroyed &&
           self.options.keepAlive) {
         var freeSockets = self.freeSockets[name];
-        var count = freeSockets ? freeSockets.length : 0;
+        var freeLen = freeSockets ? freeSockets.length : 0;
+        var count = freeLen;
         if (self.sockets[name])
           count += self.sockets[name].length;
 
-        if (count > self.maxSockets) {
+        if (count >= self.maxSockets || freeLen >= self.maxFreeSockets) {
+          self.removeSocket(socket, options);
           socket.destroy();
         } else {
           freeSockets = freeSockets || [];
@@ -92,9 +95,11 @@ function Agent(options) {
           socket.setKeepAlive(true, self.keepAliveMsecs);
           socket.unref();
           socket._httpMessage = null;
+          self.removeSocket(socket, options);
           freeSockets.push(socket);
         }
       } else {
+        self.removeSocket(socket, options);
         socket.destroy();
       }
     }
@@ -146,10 +151,13 @@ Agent.prototype.addRequest = function(req, options) {
     this.sockets[name] = [];
   }
 
-  if (this.freeSockets[name] && this.freeSockets[name].length) {
+  var freeLen = this.freeSockets[name] ? this.freeSockets[name].length : 0;
-    debug('have free socket');
+  var sockLen = freeLen + this.sockets[name].length;
+
+  if (freeLen) {
     // we have a free socket, so use that.
     var socket = this.freeSockets[name].shift();
+    debug('have free socket');
 
     // don't leak
     if (!this.freeSockets[name].length)
@@ -157,8 +165,9 @@ Agent.prototype.addRequest = function(req, options) {
 
     socket.ref();
     req.onSocket(socket);
-  } else if (this.sockets[name].length < this.maxSockets) {
+    this.sockets[name].push(socket);
-    debug('call onSocket');
+  } else if (sockLen < this.maxSockets) {
+    debug('call onSocket', sockLen, freeLen);
     // If we are under maxSockets create a new one.
     req.onSocket(this.createSocket(req, options));
   } else {

test/simple/test-http-keepalive-maxsockets.js

@@ -0,0 +1,102 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+
+var http = require('http');
+
+
+var serverSockets = [];
+var server = http.createServer(function(req, res) {
+  if (serverSockets.indexOf(req.socket) === -1) {
+    serverSockets.push(req.socket);
+  }
+  res.end(req.url);
+});
+server.listen(common.PORT);
+
+var agent = http.Agent({
+  keepAlive: true,
+  maxSockets: 5,
+  maxFreeSockets: 2
+});
+
+// make 10 requests in parallel,
+// then 10 more when they all finish.
+function makeReqs(n, cb) {
+  for (var i = 0; i < n; i++)
+    makeReq(i, then)
+
+  function then(er) {
+    if (er)
+      return cb(er);
+    else if (--n === 0)
+      setTimeout(cb);
+  }
+}
+
+function makeReq(i, cb) {
+  agent.request({ port: common.PORT, path: '/' + i }, function(res) {
+    var data = '';
+    res.setEncoding('ascii');
+    res.on('data', function(c) {
+      data += c;
+    });
+    res.on('end', function() {
+      assert.equal(data, '/' + i);
+      cb();
+    });
+  }).end();
+}
+
+var closed = false;
+makeReqs(10, function(er) {
+  assert.ifError(er);
+  assert.equal(count(agent.freeSockets), 2);
+  assert.equal(count(agent.sockets), 0);
+  assert.equal(serverSockets.length, 5);
+
+  // now make 10 more reqs.
+  // should use the 2 free reqs from the pool first.
+  makeReqs(10, function(er) {
+    assert.ifError(er);
+    assert.equal(count(agent.freeSockets), 2);
+    assert.equal(count(agent.sockets), 0);
+    assert.equal(serverSockets.length, 8);
+
+    agent.destroy();
+    server.close(function() {
+      closed = true;
+    });
+  });
+});
+
+function count(sockets) {
+  return Object.keys(sockets).reduce(function(n, name) {
+    return n + sockets[name].length;
+  }, 0);
+}
+
+process.on('exit', function() {
+  assert(closed);
+  console.log('ok');
+});