WIP: See if we can consistently repro flaky IoUringTest.ioUringIsAvailableOnLinux()

servicetalk-http-netty/src/test/java/io/servicetalk/http/netty/IoUringTest.java

@@ -25,11 +25,16 @@
 
 import io.netty.incubator.channel.uring.IOUring;
 import io.netty.incubator.channel.uring.IOUringEventLoopGroup;
+import org.junit.jupiter.api.RepeatedTest;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.EnabledOnOs;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
 import static io.servicetalk.http.api.HttpExecutionStrategies.defaultStrategy;
 import static io.servicetalk.http.api.HttpExecutionStrategies.offloadNone;
 import static io.servicetalk.http.api.HttpResponseStatus.OK;
@@ -73,7 +78,7 @@ void ioUringIsAvailableOnLinux(boolean noOffloading) throws Exception {
                     System.getProperty("os.name") + ' ' + System.getProperty("os.version"));
             IOUring.ensureAvailability();
 
-            ioUringExecutor = NettyIoExecutors.createIoExecutor(2, "io-uring");
+            ioUringExecutor = NettyIoExecutors.createIoExecutor(1, "io-uring");
             assertThat(ioUringExecutor.eventLoopGroup(), is(instanceOf(IOUringEventLoopGroup.class)));
 
             try (ServerContext serverContext = HttpServers.forAddress(localAddress(0))
@@ -92,9 +97,37 @@ void ioUringIsAvailableOnLinux(boolean noOffloading) throws Exception {
         } finally {
             IoUringUtils.tryIoUring(false);
             if (ioUringExecutor != null) {
-                ioUringExecutor.closeAsync().toFuture().get();
+                try {
+                    // It seems that if we attempt to close gracefully we never actually close down.
+                    ioUringExecutor.closeAsync().toFuture().get(10, TimeUnit.SECONDS); // the offending line.
+                } catch (TimeoutException ex) {
+                    final boolean isShutdown = ioUringExecutor.eventLoopGroup().isShutdown();
+                    StringBuilder sb = new StringBuilder();
+                    sb.append("Timed out shutting down executor. isShutdown(): ")
+                            .append(isShutdown)
+                            .append('\n');
+                    for (Map.Entry<Thread, StackTraceElement[]> entry : Thread.getAllStackTraces().entrySet()) {
+                        if (!entry.getKey().getName().startsWith("io-uring")) {
+                            // Not one of our threads.
+                            continue;
+                        }
+                        sb.append("Thread: ").append(entry.getKey().getName()).append('\n');
+                        for (StackTraceElement e : entry.getValue()) {
+                            sb.append('\t').append(e).append('\n');
+                        }
+                    }
+                    Exception next = new TimeoutException(sb.toString());
+                    next.initCause(ex);
+                    throw next;
+                }
                 assertTrue(ioUringExecutor.eventLoopGroup().isShutdown());
             }
         }
     }
+
+    @RepeatedTest(5000)
+    @EnabledOnOs(LINUX)
+    void repro() throws Exception {
+        ioUringIsAvailableOnLinux(false);
+    }
 }