1.A simple spring framework web app; 2.Use async controller to handle request; 3.Create a runnable job, use request.getInputStream to read data in its run method, then submit this job to user-defined thread pool; 4.Deploy the app and send post request to corresponding resource; 5.Use jboss-cli.sh to connect to server and monitor the value active-request of subsystem=request-controller. Then you may find the value is accumulated but do not decrease. The problem may not occur right away but after a while.   My code is like this: @PostMapping("/doAsyncNormal") public DeferredResult<ResponseEntity<String>> doAsyncNormal(HttpServletRequest request) {         System.out.println("doAsyncNormal");         final DeferredResult<ResponseEntity<String>> result = new DeferredResult<>();         asyncExecutor.execute(() -> {             try {                 String body = IOUtils.toString(request.getInputStream(), "utf-8");                 System.out.println("request body: " + body);                 Thread.sleep(20);                 result.setResult(new ResponseEntity<>("ok", HttpStatus.OK));             } catch (Throwable e) {                 e.printStackTrace();                 result.setResult(new ResponseEntity<>("error", HttpStatus.INTERNAL_SERVER_ERROR));             }         });         return result; }