I want to use Java ExecutorService in a Spring Boot application.
Multiple module of the application is called as #Scheduled.
This module calls a Process to get a result from an external application using Runtime.exec. The process is supposed to get a result which is processed by java
This method can be called as part of a Scheduled thread as well as part of a request and response which can be called 24/7 . Multiple instances of the method can be running at a time.
Is it optimum to use ExecutorService defined as a local variable like this or some other method is recommended.
The requirement is that Java should not be infinitely waiting to get a result. It should be timed out.
Here is the method called
public String getExternalInformation(String applicationPath, String command, int noOfTries)
{
ExecutorService executor = Executors.newSingleThreadExecutor();
Future<String> future;
boolean taskExecuted=false;
int trialNumber=0;
String response = "";
while((!taskExecuted)&&(trialNumber<noOfTries))
{
trialNumber++;
log.info("Starting Trial: "+trialNumber);
future= executor.submit(new TestProcessTask(applicationPath,command));
try {
System.out.println("Started Information Fetching ");
response=future.get(3, TimeUnit.MINUTES);
taskExecuted =true;
} catch (TimeoutException e) {
future.cancel(true);
System.out.println("Timed out!");
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
executor.shutdownNow();
return response;
}
The call() method of the TestProcessTask will call the Runtime.exec and parse the returning OutputStream.
I implemented Async in Spring as suggested by M. Deinum
Using the same Future methods and got it working.,
Related
If while executing one rest method, at the same time came next request also so I need to prevent the second request and respond back "One person is already using". How to achieve this in spring boot? I tried the code below given. But it's not request rejected. Its added into a queue, after first request second one will execute.
#RestController
class TestController {
private static ReentrantLock lock = new ReentrantLock();
#GetMapping("tests")
public String get() {
System.err.println("----------------------------------------1 " + lock.isLocked());
if (!lock.tryLock()) {
System.err.println("--------------------------------------2 " + lock.isLocked());
return "failed";
}
try {
System.err.println("Application Locked");
Thread.sleep(10000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
lock.unlock();
}
return "success";
}
I have a doubt about this code:
#Async
public CompletableFuture<String> doFoo() {
CompletableFuture<String> fooFuture = new CompletableFuture<>();
try {
String fooResult = longOp();
fooFuture.complete(fooResult);
} catch (Exception e) {
fooFuture.completeExceptionally(e);
}
return fooFuture;
}
The question is: does doFoo return fooFuture only after longOp has finished (either correctly or exceptionally) and is therefore returning already completed futures or is Spring doing some magic and returning before executing the body? If the code is blocking on longOp(), how would you express that the computation is being fed to an executor?
Perhaps this? Any other way?
#Async
public CompletableFuture<String> doFoo() {
CompletableFuture<String> completableFuture = new CompletableFuture<>();
CompletableFuture.runAsync(() -> {
try {
String fooResult = longOp();
completableFuture.complete(fooResult);
} catch (Exception e) {
completableFuture.completeExceptionally(e);
}
});
return completableFuture;
}
Spring actually does all of the work behind the covers so you don't have to create the CompletableFuture yourself.
Basically, adding the #Async annotation is as if you called your original method (without the annotation) like:
CompletableFuture<User> future = CompletableFuture.runAsync(() -> doFoo());
As for your second question, in order to feed it to an executor, you can specify the exectutor bean name in the value of the #Async annotation, like so:
#Async("myExecutor")
public CompletableFuture<User> findUser(String usernameString) throws InterruptedException {
User fooResult = longOp(usernameString);
return CompletableFuture.completedFuture(fooResult);
}
The above would basically be the following as if you called your original method, like:
CompletableFuture<User> future = CompletableFuture.runAsync(() -> doFoo(), myExecutor);
And all of your exceptionally logic you would do with the returned CompletableFuture from that method.
I want to write junit test case for the below code with springJunitRunner.
the below piece of code is one service in a class.
#Component
#Path(/techStack)
public class TechStackResource {
#Autowired
private transient TechStackService techStackService;
#GET
#Path("/{id}")
#Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML})
public Response getTechStackById(final #PathParam("id") Integer technicalstackid) {
final TechStackResponse response = new TechStackResponse();
int statusCode = Constants.HTTP_STATUS_OK_200;
try {
TechStackModel techStackModel = techStackService.findObjectById(technicalstackid);
response.setGetTechStackDetails(GetTechStackDetails.newBuilder().technicalStack(techStackModel).build());
if (techStackModel == null) {
statusCode = Constants.HTTP_STATUS_ERROR_404;
}
} catch (EmptyResultDataAccessException erde) {
} catch (Exception e) {
LOGGER.error("Exception occured in TechStackResource.getTechStackById(technicalstackid) ", e);
throw new APMRestException(
"Exception while executing TechStackResource.getTechStackById(technicalstackid) ",
Constants.UNKNOW_ERROR, e);
}
return Response.status(statusCode).entity(response).build();
}
}
the configuration in web.xml for servlet is
<servlet-name>jersey-servlet</servlet-name>
<servlet-class>com.sun.jersey.spi.spring.container.servlet.SpringServlet</servlet-class>
Since you are using Jersey as well as Spring, you can use the SpringJunitRunner only to wire-up TechStackResource with its dependency TechStackService.
In order to test your REST handler method getTestStackById, you could go the POJO approach and invoke it directly. Alternatively, you can use Jersey's own MockWeb environment. To find out more about this, I recommend looking at the Jersey example sources, e.g. HelloWorld.
I have a requirement where I do some operation on GUI and once I save the data in DB I need to send a http request to a webservice. But the response to GUI should not wait for result from webservice request.
For this I am using #Async , annotation of Spring.
here is my structure
MyConroller.java
calls a method
goSaveAndCreate
(not Async) in
ServiceA.java
ServiceA has a ServiceB bean injected in it. A method ,
#Async
create()
in ServiceB is annotated with Async.
Now ServiceA.goSaveAndCreate calls a method in itself , save and calls ServiceB.create() (which is Async).
I can see in logs the a new thread is created which is executing create method. But all of a sudden logs after a particular point stop and that thread seems to have got killed or comlpeted.
#Service("MarginCalculationService")
public class ServiceA implements ServiceAI {
private static final String APPROVED = "APPROVED";
public static final String SUCCESS = "SUCCESS";
....
#Autowired
ServiceB serviceB;
public List<VV> goSaveAndCreate(String[] ids,List<XX> calList) throws Exception, DataAccessException {
try {
Pair<List<VG>,List<UU>> resultList = save(ids);
vvList = resultList.getFirst();
/*
* HKAPIL - Send Message to webService callingserviceB
*/
if(resultList.getSecond() != null){
serviceB.create(resultList.getSecond());
}
} catch (DataAccessException e) {
e.printStackTrace();
logger.error("Data Access Exception thrown during - " , e);
throw e;
} catch (Exception e){
e.printStackTrace();
logger.error("Exception thrown during " , e);
throw e;
}
System.out.println("Exiting the method in MCSERVICE");
return vvList;
}
private save(){
...
...
}
}
Second service
#Service("wireInstructionMessageService")
public class ServiceB implements ServiceBI {
#Async
#Override
public void create(List<Ralc> calcList) {
String threadName = Thread.currentThread().getName();
logger.info("Inside a different thread [" + threadName + " ] to send message ." );
..
...
otherMethod(Obj);
}
private otherMethod(Obj obj){
...
...
..
//tills this point logs are getting printed nothing after this
..
...
}
}
applciationContext.xml entry
<!-- Defines a ThreadPoolTaskExecutor instance with configurable pool size, queue-capacity, keep-alive,
and rejection-policy values. The id becomes the default thread name prefix -->
<task:executor id="MyMessageExecutor"
pool-size="5-25"
queue-capacity="100"/>
<task:annotation-driven executor="MyMessageExecutor"/>
Now I have two question
1) is there a way I can add some logs in some method which tell taht the new thread from MyExecutor is getting killed or MyExecutor is getting closed (the way we have in normal Java ExecutorSerrvice)
2) Am I using the Asyn in wrong way? Is it possible that as soon as method returns from Controller or ServiceA , ServiceB instance also is getting cleaned?
Thanks
HKapil
I am using Spring with Hibernate in my project.There are many methods written in DAO implementation java file and every method is using the same try/catch/finally lines of code which seem redundant to me.
I am told to optimize/refactor the code since the file LOC exceeds 10k.I read somewhere that using HibernateDaoSupport we need not to worry about exceptions or closing the session. It will be taken care of by Spring itself.
Could somebody please help me how to proceed or do the needful or any better way to handle exceptions?I am pasting below code of one method in DAO layer.
public class CSDDaoImpl extends HibernateDaoSupport implements CSDDao {
public Deal getDealStructure(long dealId) throws CSDServiceException {
Session session = null;
try {
session = getSession();
Deal deal = (Deal) session.createCriteria(Deal.class).add(
Restrictions.eq("dealId", dealId)).uniqueResult();
return deal;
} catch (DataAccessResourceFailureException darfex) {
String message = "Failed to retrieve the deal object.";
CSDServiceException ex = new CSDServiceException(message, darfex);
ex.setStackTrace(darfex.getStackTrace());
ex.setErrorCode(Constants.DATA_ACCESS_FAILURE_EXP);
ex.setMessageToUser(message);
throw ex;
} catch (IllegalStateException isex) {
String message = "Failed to retrieve the deal object.";
CSDServiceException ex = new CSDServiceException(message, isex);
ex.setStackTrace(isex.getStackTrace());
ex.setErrorCode(Constants.ILLEGAL_STATE_EP);
ex.setMessageToUser(message);
throw ex;
} catch (HibernateException hbex) {
String message = "Failed to retrieve the deal object.";
CSDServiceException ex = new CSDServiceException(message, hbex);
ex.setStackTrace(hbex.getStackTrace());
ex.setErrorCode(Constants.HIBERNATE_EXP);
ex.setMessageToUser(message);
throw ex;
} finally {
if (session != null && session.isOpen()) {
try {
session.close();
} catch (HibernateException hbex) {
log.error("Failed to close the Hibernate Session.", hbex);
hbex.printStackTrace();
CSDServiceException ex = new CSDServiceException(
"Failed to close the Hibernate Session.", hbex);
ex.initCause(hbex.getCause());
ex.setStackTrace(hbex.getStackTrace());
throw ex;
}
}
}
}
}
The best approach of handling exceptions is i believe through writing an Exception Interceptor to intercept all your DAO calls and you can catch the ones you only need in your application and wrap it with your own custom application specific exceptions.
You definitely do not need to work directly with session once an exception is thrown. That would defeat the purpose of using HibernateDaoSupport and Spring.
Have a look at this link : http://static.springsource.org/spring/docs/current/spring-framework-reference/html/classic-spring.html
Hope that helps.