Cucumber Guice / Injector seems not to be thread-safe (Parallel execution / ExecutorService) - thread-safety

Question

[long description warning]
I'm running some cucumber tests which have to be executed intercalated a defined server - for instance:
a.feature -> JBoss Server 1 | b.feature -> JBoss Serv. 2 | c.feature -> JB1 | etc.
For that, I created a hypothetical ExecutorService like this:
final ExecutorService executorService = Executors.newFixedThreadPool(2); //numberOfServers
for (Runnable task : tasks) {
executorService.execute(task);
}
executorService.shutdown();
try {
executorService.awaitTermination(1000, TimeUnit.SECONDS);
} catch (InterruptedException e) {
//doX();
}
The way that I manage about how will be the server chosen as liable to execute is:
inside of my Runnable class created for the executorService, I pass as a parameter a instanceId to a TestNG (XmlTest class) as below:
#Override
public void run() {
setupTest().run();
}
private TestNG setupTest() {
TestNG testNG = new TestNG();
XmlSuite xmlSuite = new XmlSuite();
XmlTest xmlTest = new XmlTest(xmlSuite);
xmlTest.setName(//irrelevant);
xmlTest.addParameter("instanceId", String.valueOf(instanceId));
xmlTest.setXmlClasses(..........);
testNG.setXmlSuites(..........);
return testNG;
}
Then, I get this just fine in a class that extends TestNgCucumberAdaptor:
#BeforeTest
#Parameters({"instanceId"})
public void setInstanceId(#Optional("") String instanceId) {
if (!StringUtils.isEmpty(instanceId)) {
this.instanceId = Integer.valueOf(instanceId);
}
}
And inside a #BeforeClass I'm populating a Pojo with this instanceId and setting the Pojo in a threadLocal attribute of another class. So far, so good.
public class CurrentPojoContext {
private static final ThreadLocal<PojoContext> TEST_CONTEXT = new ThreadLocal<PojoContext>();
...
public static PojoContext getContext(){
TEST_CONTEXT.get();
}
Now the problem really starts - I'm using Guice (Cucumber guice as well) in a 3rd class, injecting this pojo object that contains the instanceId. The example follows:
public class Environment {
protected final PojoContext pojoContext;
#Inject
public Environment() {
this.pojoContext = CurrentPojoContext.getContext();
}
public void foo() {
print(pojoContext.instanceId); // output: 1
Another.doSomething(pojoContext);
}
class Another{
public String doSomething(PojoContext p){
print(p.instanceId); // output: 2
}
}
}
Here it is not every time like this the outputs (1 and 2) but from time to time, I realized that the execution of different threads is messing with the attribute pojoContext. I know that is a little confusing, but my guess is that the Guice Injector is not thread-safe for this scenario - it might be a long shot, but I'd appreciate if someone else takes a guess.
Regards

Answer 1

Well, just in order to provide a solution for someone else, my solution was the following:
Create a class that maintains a Map with an identifier (unique and thread-safe one) as the key and a Guice Injector as value;
Inside my instantiation of Guice injector, I created my own module
Guice.createInjector(Stage.PRODUCTION, MyOwnModules.SCENARIO, new RandomModule());
and for this module:
public class MyOwnModules {
public static final Module SCENARIO = new ScenarioModule(MyOwnCucumberScopes.SCENARIO);
}
the scope defined here provides the following:
public class MyOwnCucumberScopes {
public static final ScenarioScope SCENARIO = new ParallelScenarioScope();
}
To sum up, the thread-safe will be in the ParallelScenarioScope:
public class ParallelScenarioScope implements ScenarioScope {
private static final Logger LOGGER = Logger.getLogger(ParallelScenarioScope.class);
private final ThreadLocal<Map<Key<?>, Object>> threadLocalMap = new ThreadLocal<Map<Key<?>, Object>>();
#Override
public <T> Provider<T> scope(final Key<T> key, final Provider<T> unscoped) {
return new Provider<T>() {
public T get() {
Map<Key<?>, Object> scopedObjects = getScopedObjectMap(key);
#SuppressWarnings("unchecked")
T current = (T) scopedObjects.get(key);
if (current == null && !scopedObjects.containsKey(key)) {
current = unscoped.get();
scopedObjects.put(key, current);
}
return current;
}
};
}
protected <T> Map<Key<?>, Object> getScopedObjectMap(Key<T> key) {
Map<Key<?>, Object> map = threadLocalMap.get();
if (map == null) {
throw new OutOfScopeException("Cannot access " + key + " outside of a scoping block");
}
return map;
}
#Override
public void enterScope() {
checkState(threadLocalMap.get() == null, "A scoping block is already in progress");
threadLocalMap.set(new ConcurrentHashMap<Key<?>, Object>());
}
#Override
public void exitScope() {
checkState(threadLocalMap.get() != null, "No scoping block in progress");
threadLocalMap.remove();
}
private void checkState(boolean expression, String errorMessage) {
if (!expression) {
LOGGER.info("M=checkState, Will throw exception: " + errorMessage);
throw new IllegalStateException(errorMessage);
}
}
}
Now the gotcha is just to be careful regarding the #ScenarioScoped and the code will work as expected.