Spring Boot application blocking StreamingResponseBody

Question

I have a Spring Boot application where I created a POST method that sends data in a streaming fashion to the caller. Code below:

@RequestMapping(value = "/mapmatchstreaming", method = RequestMethod.POST)
public ResponseEntity<StreamingResponseBody> handleRequest(@RequestParam(value = "data", required = true) String data, @RequestParam(value = "mnr", required = true) Boolean mnr) {
    logger.info("/mapmatchstreaming endpoint");

    try {
        Semaphore semaphore = new Semaphore(1);
        ObjectMapper mapper = new ObjectMapper();

        StreamingResponseBody responseBody = new StreamingResponseBody() {
            @Override
            public void writeTo (OutputStream outputStream) throws IOException {
                // For each map
                DataReader dataReader = new DataReader(data, "2020.06.011");

                for(String mapRoot: dataReader.getMapsFolders()) {
                    dataReader = new DataReader(data, "2020.06.011");
                    DistributedMapMatcherStreaming distributedMapMatcher = new DistributedMapMatcherStreaming(dataReader.getTraces(), mapRoot, dataReader.getBoundingBox());
                    distributedMapMatcher.mapMatchBatch(new DistributedMapMatcherResult() {
                        @Override
                        public void onCorrectlyMapMatched(MapMatchedTrajectory mapMatchedTrajectory) {
                            try {
                                semaphore.acquire();
                                outputStream.write(mapper.writeValueAsString(mapMatchedTrajectory).getBytes());
                                outputStream.flush();
                            }
                            catch (Exception e) {
                                e.printStackTrace();
                                logger.error(String.format("Writing to output stream error: %s", e.getMessage()));
                            } finally{
                                semaphore.release();
                            }
                        }
                    });
                }
            }
        };

        return new ResponseEntity<StreamingResponseBody>(responseBody, HttpStatus.OK);
    }
    catch (Exception e) {
        logger.error(String.format("Map-matching result ERROR: %s", ExceptionUtils.getStackTrace(e)));
        return new ResponseEntity<StreamingResponseBody>(HttpStatus.BAD_REQUEST);
    }
}

It works nicely, but the problem is that if multiple calls arrive to this method, all of them are run in parallel even if I have set server.tomcat.threads.max=1. In the non-streaming version, every next call waits for the current one to complete.

Is it possible to have blocking streaming calls in Spring? Thanks.

EDIT: I temporarily solved by using a global semaphore with only 1 permit, but I don't think this is the ideal solution.