From 5ad80c5887c0520c0b26304ad5a3d29552b27775 Mon Sep 17 00:00:00 2001
From: greenjustin <72885340+greenjustin@users.noreply.github.com>
Date: Sat, 24 Oct 2020 08:56:33 -0400
Subject: [PATCH] Allow EventLoops to rethrow Error (#10694)

Motivation:

Thread.stop() works by producing a ThreadDeath error in the target thread. EventLoops swallow all Throwables, which makes them effectively unkillable. This is effectively a memory leak, for our application. Beside this we should also just regrow all `Error` as there is almost no way to recover.

Modification:

Edit the EventLoops that swallow Throwables to instead rethrow Error.

Result:

`EventLoop` can crash if `Error` is thrown
---
 .../src/main/java/io/netty/channel/epoll/EpollHandler.java    | 4 +++-
 .../src/main/java/io/netty/channel/kqueue/KQueueHandler.java  | 2 ++
 transport/src/main/java/io/netty/channel/nio/NioHandler.java  | 2 ++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollHandler.java b/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollHandler.java
index f406d7883a..9b53790a14 100644
--- a/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollHandler.java
+++ b/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollHandler.java
@@ -298,7 +298,7 @@ public class EpollHandler implements IoHandler {
             int strategy = selectStrategy.calculateStrategy(selectNowSupplier, !context.canBlock());
             switch (strategy) {
                 case SelectStrategy.CONTINUE:
-                    return 0 ;
+                    return 0;
 
                 case SelectStrategy.BUSY_WAIT:
                     strategy = epollBusyWait();
@@ -345,6 +345,8 @@ public class EpollHandler implements IoHandler {
                 //increase the size of the array as we needed the whole space for the events
                 events.increase();
             }
+        } catch (Error error) {
+            throw error;
         } catch (Throwable t) {
             handleLoopException(t);
         }
diff --git a/transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueHandler.java b/transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueHandler.java
index b2538bc761..275ee3a8b7 100644
--- a/transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueHandler.java
+++ b/transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueHandler.java
@@ -306,6 +306,8 @@ public final class KQueueHandler implements IoHandler {
                 //increase the size of the array as we needed the whole space for the events
                 eventList.realloc(false);
             }
+        } catch (Error e) {
+            throw e;
         } catch (Throwable t) {
             handleLoopException(t);
         }
diff --git a/transport/src/main/java/io/netty/channel/nio/NioHandler.java b/transport/src/main/java/io/netty/channel/nio/NioHandler.java
index 0469ca1dfb..aaad93fec8 100644
--- a/transport/src/main/java/io/netty/channel/nio/NioHandler.java
+++ b/transport/src/main/java/io/netty/channel/nio/NioHandler.java
@@ -451,6 +451,8 @@ public final class NioHandler implements IoHandler {
             cancelledKeys = 0;
             needsToSelectAgain = false;
             handled = processSelectedKeys();
+        } catch (Error e) {
+            throw e;
         } catch (Throwable t) {
             handleLoopException(t);
         }