prevent double registration of sockets when backpressure is resolved

actix-server/CHANGES.md

@@ -2,6 +2,10 @@
 
 ## Unreleased - 2020-xx-xx
 * Added explicit info log message on accept queue pause. [#215]
+* Prevent double registration of sockets when back-pressure is resolved. [#223]
+
+[#215]: https://github.com/actix/actix-net/pull/215
+[#223]: https://github.com/actix/actix-net/pull/223
 
 
 ## 1.0.4 - 2020-09-12

actix-server/src/accept.rs

@@ -370,6 +370,11 @@ impl Accept {
             if !on {
                 self.backpressure = false;
                 for (token, info) in self.sockets.iter() {
+                    if info.timeout.is_some() {
+                        // socket will attempt to re-register itself when its timeout completes
+                        continue;
+                    }
+
                     if let Err(err) = self.register(token, info) {
                         error!("Can not resume socket accept process: {}", err);
                     } else {