IoUring: Submit and process completions in a loop to ensure timely processing. (#15544)

normanmaurer · web-flow · commit c4ac6613b3bc · 2025-08-12T14:11:33.000+02:00
Motivation: We should contine to submit and proccess completions in a loop to ensure timely execution before return and start to process tasks. This is also more inline with other transports like epoll / nio etc. Modifications: Only return from method once we could not submit anything new and did not see anymore completions. Result: More timely processing of io. Fixes #15502
diff --git a/transport-classes-io_uring/src/main/java/io/netty/channel/uring/IoUringIoHandler.java b/transport-classes-io_uring/src/main/java/io/netty/channel/uring/IoUringIoHandler.java
@@ -184,13 +184,18 @@ public int run(IoHandlerContext context) {
     private int processCompletionsAndHandleOverflow(SubmissionQueue submissionQueue, CompletionQueue completionQueue,
                                          CompletionCallback callback) {
         int processed = 0;
-        for (;;) {
+        // Bound the maximum number of times this will loop before we return and so execute some non IO stuff.
+        // 128 here is just some sort of bound and another number might be ok as well.
+        for (int i = 0; i < 128; i++) {
             int p = completionQueue.process(callback);
             if ((submissionQueue.flags() & Native.IORING_SQ_CQ_OVERFLOW) != 0) {
                 logger.warn("CompletionQueue overflow detected, consider increasing size: {} ",
                         completionQueue.ringEntries);
                 submitAndClearNow(submissionQueue);
-            } else if (p == 0) {
+            } else if (p == 0 &&
+                    // Let's try to submit again and check if there are new completions to handle.
+                    // Only break the loop if there was nothing submitted and there are no new completions.
+                    submitAndClearNow(submissionQueue) == 0 && !completionQueue.hasCompletions()) {
                 break;
             }
 
