I am working on a project in which I need to make an HTTP URL call to my server, running RESTful service, which returns the response as a JSON String. I am using RestTemplate here along with HttpComponentsClientHttpRequestFactory to execute a URL.I have set up an HTTP request timeout (READ and CONNECTION time out) on my RestTemplate by using HttpComponentsClientHttpRequestFactory.Here is my main code which is using the future and callables:public class TimeoutThreadExample {    private ExecutorService executor = Executors.newFixedThreadPool(10);    // does it have to be static final?    private static final RestTemplate restTemplate = createRestTemplate();    // does this look right with the way I am creating `RestTemplate`?    private static RestTemplate createRestTemplate(){        // is it ok to create a new instance of HttpComponentsClientHttpRequestFactory everytime?       HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();       requestFactory.setReadTimeout(READ_TIME_OUT);       requestFactory.setConnectTimeout(CONNECTION_TIME_OUT);       return new RestTemplate(requestFactory);     }    public String getData() {        Future<String> future = executor.submit(new Task(restTemplate));        String response = null;        try {            response = future.get(500, TimeUnit.MILLISECONDS);        } catch (TimeoutException e) {            e.printStackTrace();        } catch (InterruptedException e) {            e.printStackTrace();        } catch (ExecutionException e) {            e.printStackTrace();        }        return response;    }}Here is my Task class which implements the Callable interface and uses the RestTemplate:class Task implements Callable<String> {    private RestTemplate restTemplate;    public Task(RestTemplate restTemplate) {        this.restTemplate = restTemplate;    }    public String call() throws Exception {        String url = some_url;        String response = restTemplate.getForObject(url, String.class);        return response;    }}Now I have everything working in my above code. Is the way I am creating RestTemplate along with HttpComponentsClientHttpRequestFactory thread-safe and efficient? Since RestTemplate is very heavy to be created so not sure whether I have it right or not. I'd like to improve anything in creation of RestTemplate with HttpComponentsClientHttpRequestFactory.
Using RestTemplate with HttpComponentsClientHttpRequestFactory in a multithreaded environment
java;performance;multithreading;rest
Will you have many instances of TimeoutThreadExample in your real application? If not, then the restTemplate field will be better non-static, initialized in the constructor:private final RestTemplate restTemplate;public TimeoutThreadExample() {    HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();    requestFactory.setReadTimeout(READ_TIME_OUT);    requestFactory.setConnectTimeout(CONNECTION_TIME_OUT);    restTemplate = new RestTemplate(requestFactory);}On the other hand, if you will have many instances of TimeoutThreadExample, then it will be better to make restTemplate static, and initialize it in a static initializer block instead of using a method:private static final RestTemplate restTemplate;static {    HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();    requestFactory.setReadTimeout(READ_TIME_OUT);    requestFactory.setConnectTimeout(CONNECTION_TIME_OUT);    restTemplate = new RestTemplate(requestFactory);}As for this question:// is it ok to create a new instance of HttpComponentsClientHttpRequestFactory everytime?In both alternatives I offered, the instance is really created only once, so that's ok.The way I am creating RestTemplate along with HttpComponentsClientHttpRequestFactory is thread safe and efficient?Initializing static variables is thread safe. And since you're creating RestTemplate and HttpComponentsClientHttpRequestFactory only once, it's efficient too.