I am creating a spring boot application which connects to multiple REST services and write the responses on outputStream. I am also using multiple threads to call the REST services.

 public ResponseEntity<StreamingResponseBody> startBombing(Request request) {
        int numberOfThreads = request.getConfig().getNumberOfThreads() ==0?5:request.getConfig().getNumberOfThreads();

         long requestPerThread = request.getConfig().getRequestPerThread() ==0 ? 100: request.getConfig().getRequestPerThread();



        StreamingResponseBody responseBody = response -> {
            for (int i = 1; i <= numberOfThreads; i  ) {
                int finalI = i;
                Runnable r1 = () -> {
                    try {
                        for (int j = 1; j <= requestPerThread; j  ) {
                            HttpRequest req = createRequest(request.getHttpRequest());
                            Object res = doRequest(req);

                            System.out.println("Thread number: "   finalI   ": "   "call number: "   j   "TimeStamp: "   System.currentTimeMillis()   ":::: RESPONSE: "   res);
                            response.write(("Thread number: "   finalI   ": "   "call number: "   j   "TimeStamp: "   System.currentTimeMillis()   ":::: RESPONSE: "   res).getBytes());

                        }
                    } catch (Exception e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                };

                Thread t1 = new Thread(r1);
                t1.start();
            }
        };
        return ResponseEntity.ok()
                .contentType(MediaType.TEXT_PLAIN)
                .body(responseBody);
    }

No data is printed on the output stream.

Any clue how to reuse same outputStream in muliple threads

CodePudding user response：

Wait for all threads to finish before exiting lambda (as it will close the output for you)

StreamingResponseBody responseBody = response -> {
        CountDownLatch latch=new CountDownLatch(numberOfThreads);
        for (int i = 1; i <= numberOfThreads; i  ) {
            int finalI = i;
            Runnable r1 = () -> {
                try {
                    //ireelevant code
                } finally{
                    latch.countDown(); // decrease latch counter
                }
            };

            Thread t1 = new Thread(r1);
            t1.start();
        }
     latch.await(); // wait for latch to count down to 0   add error handling and return value
    };