Fix very rare deadlock

lukebakken · lukebakken · commit c48822cfff3f · 2025-01-22T13:05:41.000-08:00
Fixes #1751 Attempt to fix deadlock by waiting on channel dispatcher first, then channel reader.
diff --git a/projects/RabbitMQ.Client/ConsumerDispatching/ConsumerDispatcherChannelBase.cs b/projects/RabbitMQ.Client/ConsumerDispatching/ConsumerDispatcherChannelBase.cs
@@ -161,10 +161,17 @@ public async Task WaitForShutdownAsync()
             {
                 try
                 {
-                    await _reader.Completion
-                        .ConfigureAwait(false);
                     await _worker
                         .ConfigureAwait(false);
+
+                    /*
+                     * rabbitmq/rabbitmq-dotnet-client#1751
+                     *
+                     * Wait for the worker first to ensure all items have been read out of the channel,
+                     * otherwise the following will never return (https://stackoverflow.com/a/66521303)
+                     */
+                    await _reader.Completion
+                        .ConfigureAwait(false);
                 }
                 catch (AggregateException aex)
                 {

Original file line number	Diff line number	Diff line change
`@@ -161,10 +161,17 @@ public async Task WaitForShutdownAsync()`
`161`	`161`	`{`
`162`	`162`	`try`
`163`	`163`	`{`
`164`		`- await _reader.Completion`
`165`		`- .ConfigureAwait(false);`
`166`	`164`	`await _worker`
`167`	`165`	`.ConfigureAwait(false);`
	`166`	`+`
	`167`	`+ /*`
	`168`	`+ * rabbitmq/rabbitmq-dotnet-client#1751`
	`169`	`+ *`
	`170`	`+ * Wait for the worker first to ensure all items have been read out of the channel,`
	`171`	`+ * otherwise the following will never return (https://stackoverflow.com/a/66521303)`
	`172`	`+ */`
	`173`	`+ await _reader.Completion`
	`174`	`+ .ConfigureAwait(false);`
`168`	`175`	`}`
`169`	`176`	`catch (AggregateException aex)`
`170`	`177`	`{`