java - Concurrent SQS queue listeners -

i don't understand how sqs queuelistener works.

this config:

    /**      * aws credentials bean      */     @bean     public awscredentials awscredentials() {         return new basicawscredentials(accesskey, secretaccesskey);     }      /**      * aws client bean      */     @bean     public amazonsqs amazonsqsasyncclient() {         amazonsqs sqsclient = new amazonsqsclient(awscredentials());         sqsclient.setregion(region.getregion(regions.us_east_1));         return sqsclient;     }      /**      * aws connection factory      */     @bean     public sqsconnectionfactory connectionfactory() {         sqsconnectionfactory.builder factorybuilder = new sqsconnectionfactory.builder(                 region.getregion(regions.us_east_1));         factorybuilder.setawscredentialsprovider(new awscredentialsprovider() {              @override             public awscredentials getcredentials() {                 return awscredentials();             }              @override             public void refresh() {             }          });         return factorybuilder.build();     }      /**      * registering queuelistener queuename      */     @bean     public defaultmessagelistenercontainer defaultmessagelistenercontainer() {         defaultmessagelistenercontainer messagelistenercontainer = new defaultmessagelistenercontainer();         messagelistenercontainer.setconnectionfactory(connectionfactory());         messagelistenercontainer.setdestinationname(queuename);         messagelistenercontainer.setmessagelistener(new messagelisteneradapter(new labqueuelistener()));         messagelistenercontainer.seterrorhandler(new queuelistenererrorhandler());         messagelistenercontainer.settaskexecutor(executors.newfixedthreadpool(3));          return messagelistenercontainer;     } 

as can see, have configured defaultmessagelistenercontainer executors.newfixedthreadpool(3)

this way expect have 3 concurrent task execution in queue listener @ 1 time.

thsi listener logic:

public class queuelistener {      public void handlemessage(string messagecontent) {         try {             logger.info(string.format("message received: %s", messagecontent));             logger.info("wait 30 sec");             thread.sleep(1000 * 30);             logger.info("done");         } catch (throwable th) {             throw new queuelistenerexception(messagecontent, th);         }     } } 

right each handlemessage method blocks (thread.sleep(1000 * 30);) execution 30 seconds , 1 handlemessage method executes @ 1 time.

what doing wrong ? how achieve concurrent handlemessage method invocation @ 1 time ? current configuration expect have 3 handlemessage performed simultaneously.

you can add parameter handle concurrent execution in bean defaultmessagelistenerconfigurator adding messagelistenercontainer.setconcurrency("3-10"); means start 3 threads , scale 10.
number of concurrentconsumers can alternatively set using messagelistenercontainer.setconcurrentconsumers(3);

refer: https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/jms/listener/defaultmessagelistenercontainer.html#setconcurrency-java.lang.string-