use a threadpool for fetch

Cargo.lock

@@ -2791,6 +2791,7 @@ dependencies = [
  "openssl 0.10.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "pixels 0.0.1",
  "profile_traits 0.0.1",
+ "rayon 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.80 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "servo_allocator 0.0.1",

components/net/Cargo.toml

@@ -44,6 +44,7 @@ net_traits = {path = "../net_traits"}
 openssl = "0.10"
 pixels = {path = "../pixels"}
 profile_traits = {path = "../profile_traits"}
+rayon = "1"
 serde = "1.0"
 serde_json = "1.0"
 servo_allocator = {path = "../allocator"}

components/net/resource_thread.rs

@@ -398,6 +398,7 @@ pub struct CoreResourceManager {
     devtools_chan: Option<Sender<DevtoolsControlMsg>>,
     swmanager_chan: Option<IpcSender<CustomResponseMediator>>,
     filemanager: FileManager,
+    fetch_pool: rayon::ThreadPool,
 }
 
 impl CoreResourceManager {
@@ -407,11 +408,16 @@ impl CoreResourceManager {
         _profiler_chan: ProfilerChan,
         embedder_proxy: EmbedderProxy,
     ) -> CoreResourceManager {
+        let pool = rayon::ThreadPoolBuilder::new()
+            .num_threads(16)
+            .build()
+            .unwrap();
         CoreResourceManager {
             user_agent: user_agent,
             devtools_chan: devtools_channel,
             swmanager_chan: None,
             filemanager: FileManager::new(embedder_proxy),
+            fetch_pool: pool,
         }
     }
 
@@ -446,9 +452,7 @@ impl CoreResourceManager {
             _ => ResourceTimingType::Resource,
         };
 
-        thread::Builder::new()
+        self.fetch_pool.spawn(move || {
-            .name(format!("fetch thread for {}", request_builder.url))
-            .spawn(move || {
             let mut request = request_builder.build();
             // XXXManishearth: Check origin against pipeline id (also ensure that the mode is allowed)
             // todo load context / mimesniff in fetch
@@ -459,9 +463,7 @@ impl CoreResourceManager {
                 user_agent: ua,
                 devtools_chan: dc,
                 filemanager: filemanager,
-                    cancellation_listener: Arc::new(Mutex::new(CancellationListener::new(
+                cancellation_listener: Arc::new(Mutex::new(CancellationListener::new(cancel_chan))),
-                        cancel_chan,
-                    ))),
                 timing: Arc::new(Mutex::new(ResourceFetchTiming::new(request.timing_type()))),
             };
 
@@ -480,8 +482,7 @@ impl CoreResourceManager {
                 },
                 None => fetch(&mut request, &mut sender, &context),
             };
-            })
+        });
-            .expect("Thread spawning failed");
     }
 
     fn websocket_connect(

tests/wpt/mozilla/meta/MANIFEST.json

@@ -13052,6 +13052,19 @@
      {}
     ]
    ],
+   "mozilla/fetch_cannot_overwhelm_system.window.js": [
+    [
+     "mozilla/fetch_cannot_overwhelm_system.window.html",
+     {
+      "script_metadata": [
+       [
+        "title",
+        "Ensure multiple fetch do not crash the browser."
+       ]
+      ]
+     }
+    ]
+   ],
    "mozilla/first-reflow-sheet-assert.html": [
     [
      "mozilla/first-reflow-sheet-assert.html",
@@ -20057,6 +20070,10 @@
    "0ba1ce0d5577de68e5e8ff3acbce52043e7dee43",
    "testharness"
   ],
+  "mozilla/fetch_cannot_overwhelm_system.window.js": [
+   "989231e9caedd099f5212bd2f9d377c83f929a22",
+   "testharness"
+  ],
   "mozilla/first-reflow-sheet-assert.html": [
    "268af6d333f04adc35974ca3f2e9ebb29783fd2e",
    "testharness"

tests/wpt/mozilla/meta/mozilla/fetch_cannot_overwhelm_system.window.js.ini

@@ -0,0 +1,3 @@
+[fetch_cannot_overwhelm_system.window.html]
+  expected:
+      if os == "linux": CRASH

tests/wpt/mozilla/tests/mozilla/fetch_cannot_overwhelm_system.window.js

@@ -0,0 +1,15 @@
+// META: title=Ensure multiple fetch do not crash the browser.
+
+async_test(function(t) {
+  onload = t.step_func(function() {
+    var step;
+    var xhr
+    var url = '/';
+    t.step_timeout(t.step_func_done(), 10);
+    for (step = 0; step < 5000; step++) {
+      xhr = new XMLHttpRequest();
+      xhr.open('GET', url, true);
+      xhr.send();
+    }
+  });
+});