runtime: create reactor per worker (#660)

Cargo.toml

@@ -54,6 +54,7 @@ appveyor = { repository = "carllerche/tokio", id = "s83yxhy9qeb58va7" }
 
 [dependencies]
 bytes = "0.4"
+num_cpus = "1.8.0"
 tokio-codec = { version = "0.1.0", path = "tokio-codec" }
 tokio-current-thread = { version = "0.1.3", path = "tokio-current-thread" }
 tokio-io = { version = "0.1.6", path = "tokio-io" }

src/lib.rs

@@ -76,6 +76,7 @@ extern crate bytes;
 #[macro_use]
 extern crate futures;
 extern crate mio;
+extern crate num_cpus;
 extern crate tokio_current_thread;
 extern crate tokio_io;
 extern crate tokio_executor;

src/runtime/builder.rs

@@ -3,11 +3,12 @@ use runtime::{Inner, Runtime};
 use reactor::Reactor;
 
 use std::io;
+use std::sync::Mutex;
 use std::time::Duration;
 
+use num_cpus;
 use tokio_reactor;
 use tokio_threadpool::Builder as ThreadPoolBuilder;
-use tokio_threadpool::park::DefaultPark;
 use tokio_timer::clock::{self, Clock};
 use tokio_timer::timer::{self, Timer};
 
@@ -51,6 +52,9 @@ pub struct Builder {
     /// Thread pool specific builder
     threadpool_builder: ThreadPoolBuilder,
 
+    /// The number of worker threads
+    core_threads: usize,
+
     /// The clock to use
     clock: Clock,
 }
@@ -61,11 +65,15 @@ impl Builder {
     ///
     /// Configuration methods can be chained on the return value.
     pub fn new() -> Builder {
+        let core_threads = num_cpus::get().max(1);
+
         let mut threadpool_builder = ThreadPoolBuilder::new();
         threadpool_builder.name_prefix("tokio-runtime-worker-");
+        threadpool_builder.pool_size(core_threads);
 
         Builder {
             threadpool_builder,
+            core_threads,
             clock: Clock::new(),
         }
     }
@@ -110,6 +118,7 @@ impl Builder {
     /// # }
     /// ```
     pub fn core_threads(&mut self, val: usize) -> &mut Self {
+        self.core_threads = val;
         self.threadpool_builder.pool_size(val);
         self
     }
@@ -243,44 +252,50 @@ impl Builder {
     /// # }
     /// ```
     pub fn build(&mut self) -> io::Result<Runtime> {
-        use std::collections::HashMap;
-        use std::sync::{Arc, Mutex};
+        // TODO(stjepang): Once we remove the `threadpool_builder` method, remove this line too.
+        self.threadpool_builder.pool_size(self.core_threads);
+
+        let mut reactor_handles = Vec::new();
+        let mut timer_handles = Vec::new();
+        let mut timers = Vec::new();
+
+        for _ in 0..self.core_threads {
+            // Create a new reactor.
+            let reactor = Reactor::new()?;
+            reactor_handles.push(reactor.handle());
+
+            // Create a new timer.
+            let timer = Timer::new_with_now(reactor, self.clock.clone());
+            timer_handles.push(timer.handle());
+            timers.push(Mutex::new(Some(timer)));
+        }
 
         // Get a handle to the clock for the runtime.
-        let clock1 = self.clock.clone();
-        let clock2 = clock1.clone();
+        let clock = self.clock.clone();
 
-        let timers = Arc::new(Mutex::new(HashMap::<_, timer::Handle>::new()));
-        let t1 = timers.clone();
-
-        // Spawn a reactor on a background thread.
-        let reactor = Reactor::new()?.background()?;
-
-        // Get a handle to the reactor.
-        let reactor_handle = reactor.handle().clone();
+        // Get a handle to the first reactor.
+        let reactor = reactor_handles[0].clone();
 
         let pool = self.threadpool_builder
             .around_worker(move |w, enter| {
-                let timer_handle = t1.lock().unwrap()
-                    .get(w.id()).unwrap()
-                    .clone();
+                let index = w.id().to_usize();
 
-                tokio_reactor::with_default(&reactor_handle, enter, |enter| {
-                    clock::with_default(&clock1, enter, |enter| {
-                        timer::with_default(&timer_handle, enter, |_| {
+                tokio_reactor::with_default(&reactor_handles[index], enter, |enter| {
+                    clock::with_default(&clock, enter, |enter| {
+                        timer::with_default(&timer_handles[index], enter, |_| {
                             w.run();
                         });
                     })
                 });
             })
             .custom_park(move |worker_id| {
-                // Create a new timer
-                let timer = Timer::new_with_now(DefaultPark::new(), clock2.clone());
+                let index = worker_id.to_usize();
 
-                timers.lock().unwrap()
-                    .insert(worker_id.clone(), timer.handle());
-
-                timer
+                timers[index]
+                    .lock()
+                    .unwrap()
+                    .take()
+                    .unwrap()
             })
             .build();
 

src/runtime/mod.rs

@@ -121,7 +121,7 @@ pub use self::builder::Builder;
 pub use self::shutdown::Shutdown;
 pub use self::task_executor::TaskExecutor;
 
-use reactor::{Background, Handle};
+use reactor::Handle;
 
 use std::io;
 
@@ -152,8 +152,8 @@ pub struct Runtime {
 
 #[derive(Debug)]
 struct Inner {
-    /// Reactor running on a background thread.
-    reactor: Background,
+    /// A handle to one of the per-worker reactors.
+    reactor: Handle,
 
     /// Task execution pool.
     pool: threadpool::ThreadPool,
@@ -254,6 +254,7 @@ impl Runtime {
     #[deprecated(since = "0.1.5", note = "use `reactor` instead")]
     #[doc(hidden)]
     pub fn handle(&self) -> &Handle {
+        #[allow(deprecated)]
         self.reactor()
     }
 
@@ -275,8 +276,9 @@ impl Runtime {
     ///
     /// // use `reactor_handle`
     /// ```
+    #[deprecated(since = "0.1.11", note = "there is now a reactor per worker thread")]
     pub fn reactor(&self) -> &Handle {
-        self.inner().reactor.handle()
+        &self.inner().reactor
     }
 
     /// Return a handle to the runtime's executor.
@@ -424,16 +426,7 @@ impl Runtime {
     /// [mod]: index.html
     pub fn shutdown_on_idle(mut self) -> Shutdown {
         let inner = self.inner.take().unwrap();
-
-        let inner = Box::new({
-            let pool = inner.pool;
-            let reactor = inner.reactor;
-
-            pool.shutdown_on_idle().and_then(|_| {
-                reactor.shutdown_on_idle()
-            })
-        });
-
+        let inner = inner.pool.shutdown_on_idle();
         Shutdown { inner }
     }
 

src/runtime/shutdown.rs

@@ -1,4 +1,5 @@
 use runtime::Inner;
+use tokio_threadpool as threadpool;
 
 use std::fmt;
 
@@ -6,23 +7,12 @@ use futures::{Future, Poll};
 
 /// A future that resolves when the Tokio `Runtime` is shut down.
 pub struct Shutdown {
-    pub(super) inner: Box<Future<Item = (), Error = ()> + Send>,
+    pub(super) inner: threadpool::Shutdown,
 }
 
 impl Shutdown {
     pub(super) fn shutdown_now(inner: Inner) -> Self {
-        let inner = Box::new({
-            let pool = inner.pool;
-            let reactor = inner.reactor;
-
-            pool.shutdown_now().and_then(|_| {
-                reactor.shutdown_now()
-                    .then(|_| {
-                        Ok(())
-                    })
-            })
-        });
-
+        let inner = inner.pool.shutdown_now();
         Shutdown { inner }
     }
 }

tokio-threadpool/src/worker/mod.rs

@@ -892,4 +892,12 @@ impl WorkerId {
     pub(crate) fn new(idx: usize) -> WorkerId {
         WorkerId(idx)
     }
+
+    /// Returns this identifier represented as an integer.
+    ///
+    /// Worker identifiers in a single thread pool are guaranteed to correspond to integers in the
+    /// range `0..pool_size`.
+    pub fn to_usize(&self) -> usize {
+        self.0
+    }
 }