How to improve performance of multi threading

Question

I have googled and found the best way to use multithreading but its failing for a 100 records it giving 504 status code. Is there any scope to improve the below code?

@Scheduled(fixedRate = 5000)
public ResponseEntity<Object> getData(List<JSONObject> getQuoteJson, String username,
                                      String authorization) throws ParseException, IOException, Exception {
    HttpHeaders responseHeaders = new HttpHeaders();
    responseHeaders.set("Access-Control-Allow-Origin", "*");
    CompletableFuture<JSONArray> future = null;
    JSONArray responseArray = new JSONArray();
    try {
        executor = Executors.newFixedThreadPool(getQuoteJson.size());
        for (int i = 0; i < getQuoteJson.size(); i++) {
            JSONObject jsonObject = (JSONObject) getQuoteJson.get(i);
            future = CompletableFuture.supplyAsync(() -> {
                JSONObject response = asynCallService.getDataAsyncService(jsonObject, productCode, authorization);
                responseArray.add(response);
                return responseArray;
            }, executor);
        }
        return new ResponseEntity<Object>(future.get(), responseHeaders, HttpStatus.OK);
    } catch (Exception e) {
        throw e;
    } finally {
        executor.shutdown();
        try {
            executor.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
        } catch (Exception e) {
        }
    }

}

On a sidenote: "I have [...] found the best way to use multithreading" is a statement I would be quite cautious with. There is no best way to use multithreading. More often than not there isn't even a clear "best way" for a specific use-case. — Ben, Sep 04 '18 at 10:34
https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/504 for the unititiated — Brian Agnew, Sep 04 '18 at 10:37
Given that 504 relates to a *gateway*, is that coming from a service you're calling from within your multithreaded code? — Brian Agnew, Sep 04 '18 at 10:52
`responseArray.add(response);` is probably not thread safe to use inside a future's body. — GPI, Sep 04 '18 at 11:48

xingbin · Answer 1 · 2018-09-04T10:38:10.683

3

Do not create and shutdown executor every time, use a singleton cached thread pool. Since creating threads repeatly is unecessary and expensive, and the benefit of thread pool is keeping threads existing.

edited Sep 04 '18 at 10:38

answered Sep 04 '18 at 10:32

xingbin

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Hi Sun, can you please help a bit deeper? – Sep 04 '18 at 10:38
@Soham Please check the link in the answer. Creating thread is expensive, you can use cached thread pool to avoid it. So you do not need create `executor = Executors.newFixedThreadPool(getQuoteJson.size());` every time. You can just hold a global executor. – xingbin Sep 04 '18 at 13:52

score 1 · Answer 2 · answered Sep 04 '18 at 10:48

Wow all of this to iterate asynchronly on a list ?

this is i think more likely to be what you searched :

HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.set("Access-Control-Allow-Origin", "*");
final JSONArray responseArray = new JSONArray();
getQuoteJson.parallelStream().map(e->asynCallService.getDataAsyncService(e, productCode, authorization)).forEach(responseArray::add);
return new ResponseEntity<Object>(responseArray, responseHeaders, HttpStatus.OK);

How to improve performance of multi threading

2 Answers2