os0file.c:

  Add more precise diagnostics about the state of the I/O threads of InnoDB; print in SHOW INNODB STATUS if the event wait semaphore of each I/O thread is set

innobase/os/os0file.c

@@ -2588,6 +2588,8 @@ os_aio_simulated_handle(
 	/* NOTE! We only access constant fields in os_aio_array. Therefore
 	we do not have to acquire the protecting mutex yet */
 
+	srv_set_io_thread_op_info(global_segment,
+					"looking for i/o requests (a)");
 	ut_ad(os_aio_validate());
 	ut_ad(segment < array->n_segments);
 
@@ -2606,6 +2608,9 @@ os_aio_simulated_handle(
 	
 	os_mutex_enter(array->mutex);
 
+	srv_set_io_thread_op_info(global_segment,
+					"looking for i/o requests (b)");
+
 	/* Check if there is a slot for which the i/o has already been
 	done */
 	
@@ -2718,6 +2723,8 @@ os_aio_simulated_handle(
 		}
 	}
 
+	srv_set_io_thread_op_info(global_segment, "consecutive i/o requests");
+
 	/* We have now collected n_consecutive i/o requests in the array;
 	allocate a single buffer which can hold all data, and perform the
 	i/o */
@@ -2861,6 +2868,8 @@ os_aio_simulated_handle(
 	return(ret);
 
 wait_for_io:
+	srv_set_io_thread_op_info(global_segment, "resetting wait event");
+
 	/* We wait here until there again can be i/os in the segment
 	of this thread */
 	
@@ -2952,9 +2961,15 @@ os_aio_print(
 	ulint		i;
 
 	for (i = 0; i < srv_n_file_io_threads; i++) {
-		fprintf(file, "I/O thread %lu state: %s (%s)\n", i,
+		fprintf(file, "I/O thread %lu state: %s (%s)", i,
 					srv_io_thread_op_info[i],
 					srv_io_thread_function[i]);
+
+        	if (os_aio_segment_wait_events[i]->is_set) {
+			fprintf(file, " ev set");
+		}
+			
+		fprintf(file, "\n");
 	}
 
 	fputs("Pending normal aio reads:", file);