Experiment for number of persistent connections to server

Currently Chrome, Firefox, and IE8 have the number of outgoing connections to each host(server) set at 6.
 Safari uses 4, and Fasterfox (a plugin for Firefox that supposedly
 configures it to run faster) uses 8. We would like to see how much of an
 effect this value has on browsing. Too large a value might cause us to
 run into SYN flood detection mechanisms. This experiment assigns a value of (4, 6, 8, 16) at random at program launch, and uses it throughout the run.

r=jar


Review URL: http://codereview.chromium.org/2685005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@49057 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 75 insertions, 0 deletions

diff --git a/chrome/browser/browser_main.cc b/chrome/browser/browser_main.cc
index bc78554..bd37e7d 100644
--- a/chrome/browser/browser_main.cc
+++ b/chrome/browser/browser_main.cc
@@ -714,6 +714,41 @@ int BrowserMain(const MainFunctionParams& parameters) {
   // Initialize statistical testing infrastructure for entire browser.
   FieldTrialList field_trial;
 
+  // This is an A/B test for the maximum number of persistent connections per
+  // host.  Currently Chrome, Firefox, and IE8 have this value set at 6.
+  // Safari uses 4, and Fasterfox (a plugin for Firefox that supposedly
+  // configures it to run faster) uses 8.  We would like to see how much of an
+  // effect this value has on browsing.  Too large a value might cause us to
+  // run into SYN flood detection mechanisms.
+  const FieldTrial::Probability kConnDivisor = 100;
+  const FieldTrial::Probability kConn16 = 10;  // 10% probability
+  const FieldTrial::Probability kRemainingConn = 30;  // 30% probability
+
+  scoped_refptr<FieldTrial> conn_trial =
+      new FieldTrial("ConnCountImpact", kConnDivisor);
+
+  const int conn_16 = conn_trial->AppendGroup("_conn_count_16", kConn16);
+  const int conn_4 = conn_trial->AppendGroup("_conn_count_4", kRemainingConn);
+  const int conn_8 = conn_trial->AppendGroup("_conn_count_8", kRemainingConn);
+  const int conn_6 = conn_trial->AppendGroup("_conn_count_6",
+      FieldTrial::kAllRemainingProbability);
+
+  const int conn_trial_grp = conn_trial->group();
+
+  if (conn_trial_grp == conn_4) {
+    net::HttpNetworkSession::set_max_sockets_per_group(4);
+  } else if (conn_trial_grp == conn_6) {
+    // This (6) is the current default value.
+    net::HttpNetworkSession::set_max_sockets_per_group(6);
+  } else if (conn_trial_grp == conn_8) {
+    net::HttpNetworkSession::set_max_sockets_per_group(8);
+  } else if (conn_trial_grp == conn_16) {
+    net::HttpNetworkSession::set_max_sockets_per_group(16);
+  } else {
+    DCHECK(false);
+  }
+
+
   // When --use-spdy not set, users will be in A/B test for spdy.
   // group A (_npn_with_spdy): this means npn and spdy are enabled. In
   // case server supports spdy, browser will use spdy.
diff --git a/chrome/renderer/render_view.cc b/chrome/renderer/render_view.cc
index 467d5c4..9ff9ccc 100755
--- a/chrome/renderer/render_view.cc
+++ b/chrome/renderer/render_view.cc
@@ -4571,6 +4571,46 @@ void RenderView::DumpLoadHistograms() const {
     }
   }
 
+  static bool use_conn_impact_histogram(
+      FieldTrialList::Find("ConnCountImpact") &&
+      !FieldTrialList::Find("ConnCountImpact")->group_name().empty());
+  if (use_conn_impact_histogram) {
+    UMA_HISTOGRAM_ENUMERATION(
+        FieldTrial::MakeName("Renderer4.Abandoned", "ConnCountImpact"),
+        abandoned_page ? 1 : 0, 2);
+    UMA_HISTOGRAM_ENUMERATION(
+        FieldTrial::MakeName("Renderer4.LoadType", "ConnCountImpact"),
+        load_type, NavigationState::kLoadTypeMax);
+    switch (load_type) {
+      case NavigationState::NORMAL_LOAD:
+        UMA_HISTOGRAM_CUSTOM_TIMES(FieldTrial::MakeName(
+            "Renderer4.BeginToFinish_NormalLoad", "ConnCountImpact"),
+            begin_to_finish, kBeginToFinishMin, kBeginToFinishMax,
+            kBeginToFinishBucketCount);
+        break;
+      case NavigationState::LINK_LOAD_NORMAL:
+        UMA_HISTOGRAM_CUSTOM_TIMES(FieldTrial::MakeName(
+            "Renderer4.BeginToFinish_LinkLoadNormal", "ConnCountImpact"),
+            begin_to_finish, kBeginToFinishMin, kBeginToFinishMax,
+            kBeginToFinishBucketCount);
+        break;
+      case NavigationState::LINK_LOAD_RELOAD:
+        UMA_HISTOGRAM_CUSTOM_TIMES(FieldTrial::MakeName(
+            "Renderer4.BeginToFinish_LinkLoadReload", "ConnCountImpact"),
+            begin_to_finish, kBeginToFinishMin, kBeginToFinishMax,
+            kBeginToFinishBucketCount);
+        break;
+      case NavigationState::LINK_LOAD_CACHE_STALE_OK:
+        UMA_HISTOGRAM_CUSTOM_TIMES(FieldTrial::MakeName(
+            "Renderer4.BeginToFinish_LinkLoadStaleOk", "ConnCountImpact"),
+            begin_to_finish, kBeginToFinishMin, kBeginToFinishMax,
+            kBeginToFinishBucketCount);
+        break;
+      default:
+        break;
+    }
+  }
+
   static bool use_sdch_histogram(FieldTrialList::Find("GlobalSdch") &&
       !FieldTrialList::Find("GlobalSdch")->group_name().empty());
   if (use_sdch_histogram) {