Only release GVL if there are no messages pending.

Author: alistairjevans

ext/hyper_ruby/src/lib.rs

@@ -99,9 +99,17 @@ impl Server {
         if let Some(work_rx) = self.work_rx.borrow().as_ref() {
 
             loop {
-                 // Use nogvl to wait for requests outside the GVL
-                 let work_request = nogvl(|| work_rx.recv());
-                
+                // try getting the next request without yielding the GVL, if there's nothing, wait for one
+                let work_request = match work_rx.try_recv() {
+                    Ok(work_request) => Ok(work_request),
+                    Err(crossbeam_channel::TryRecvError::Empty) => {
+                        nogvl(|| work_rx.recv())
+                    },
+                    Err(crossbeam_channel::TryRecvError::Disconnected) => {
+                        break;
+                    }
+                };
+
                  match work_request {
                     Ok(work_request) => {
                         let request = Request {

test/test_hyper_ruby.rb

@@ -79,11 +79,13 @@ def with_server(request_handler, &block)
     # Create ruby worker threads that process requests;
     # 1 is usually enough, and generally handles better than multiple threads 
     # if there's no IO (because of the GIL)
-    worker = Thread.new do
-      server.run_worker do |request|
-        # Process the request in Ruby
-        # request is a hash with :method, :path, :headers, and :body keys
-        request_handler.call(request)
+    workers = 1.times.map do
+      Thread.new do
+        server.run_worker do |request|
+          # Process the request in Ruby
+          # request is a hash with :method, :path, :headers, and :body keys
+          request_handler.call(request)
+        end
       end
     end
 
@@ -92,7 +94,7 @@ def with_server(request_handler, &block)
 
   ensure
     server.stop if server
-    worker.join if worker
+    workers.map(&:join) if workers
   end
 
   def with_unix_socket_server(request_handler, &block)
@@ -103,11 +105,13 @@ def with_unix_socket_server(request_handler, &block)
     # Create ruby worker threads that process requests;
     # 1 is usually enough, and generally handles better than multiple threads 
     # if there's no IO (because of the GIL)
-    worker = Thread.new do
-      server.run_worker do |request|
-        # Process the request in Ruby
-        # request is a hash with :method, :path, :headers, and :body keys
-        request_handler.call(request)
+    workers = 2.times.map do
+      Thread.new do
+        server.run_worker do |request|
+          # Process the request in Ruby
+          # request is a hash with :method, :path, :headers, and :body keys
+          request_handler.call(request)
+        end
       end
     end
 
@@ -117,7 +121,7 @@ def with_unix_socket_server(request_handler, &block)
 
   ensure
     server.stop if server
-    worker.join if worker
+    workers.map(&:join) if workers
   end
 
   def handler_simple(request)