Spring RestTemplate - async vs sync restTemplate

Question

I wrote the following code to test the performance of both the sync RestTemplate and AsyncRestTemplate. I just ran it a few times manually on POSTMAN.

We are just pa

Answer 1

I would say that you're missing the real benefits of the AsyncRest here. You should add callbacks to each requests you're sending so that the response will be processes only when available.

Indeed, the getForEntity method of an AsyncRestTemplate returns a ListenableFuture to which you can connect a callback task. See the official doc ListenableFuture for further information.

For example in your case it could be:

for (int i = 0; i < 10; i++) {
     ListenableFuture> response = asyncRestTemplate.getForEntity(references.get(i), String.class);
     response.addCallback(new ListenableFutureCallback>() {
            @Override
            public void onSuccess(ResponseEntity result) {
                // Do stuff onSuccess 
                links.add(result.getBody().toString());
            }

            @Override
            public void onFailure(Throwable ex) {
                log.warn("Error detected while submitting a REST request. Exception was {}", ex.getMessage());
            }
        });
}