SocketTimeoutException Read timed out on RestTemplate, PoolingHttpClientConnectionManager

Question

I am struggling with Read timed out exception.

For API call, I am using RestTemplate and it works pretty well, but the read timed out exception occured 5~6 times a day. I've spend for a while to deal with it, but I have no idea what problem of my web service causes the read timed out exception.

Here is my code and I am using Spring 4.3 and HttpClient 4.5.2 to use PoolingHttpClientConnectionManager.

Please, help me.

@Component
public class TestClient {

private RestTemplate template;

private PoolingHttpClientConnectionManager manager;

private static Logger logger = LoggerFactory.getLogger(TestClient.class);

@PostConstruct
public void init() {
    this.manager = new PoolingHttpClientConnectionManager();
    this.manager.setMaxTotal(60);
    this.manager.setDefaultMaxPerRoute(30);
    this.manager.setValidateAfterInactivity(1000 * 30);

    CloseableHttpClient client = HttpClients.custom()
            .setConnectionManager(manager)
            .build();

    HttpComponentsClientHttpRequestFactory factory = new HttpComponentsClientHttpRequestFactory(client);
    factory.setReadTimeout(1000 * 20);
    factory.setConnectionRequestTimeout(1000 * 10);
    factory.setConnectTimeout(1000 * 10);

    this.template = new RestTemplate(factory);
}

public Map<String, Object> exchange(String url, Object req, String tmonTid) {
    try {
        logger.info("Pool Stat [{}] {}", tmonTid, this.manager.getTotalStats().toString());
        RequestEntity<Object> request = RequestEntity.post(new URI(url))
                .contentType(MediaType.APPLICATION_JSON_UTF8).body(req);
        ResponseEntity<Map> ret = template.exchange(request, Map.class);

        if (HttpStatus.OK == ret.getStatusCode()) {
            return ret.getBody();
        } else {
            return MapUtils.EMPTY_MAP;
        }
    } catch (Exception e) {
       e.printStackTrace();
    }
}

}