Concurrency testing

concurrency-test.java

	@Test
	public void testQueryConcurrency(SessionFactoryScope scope) throws InterruptedException {
		final int numberOfIterations = 40;
		final int numberOfForks = 5;

		final ExecutorService executor = Executors.newFixedThreadPool( 5 );

		final List<Future<String>> futures = CollectionHelper.arrayList( numberOfIterations * numberOfForks );

		try {
			for ( int f = 0; f < numberOfForks; f++ ) {
				final ArrayList<Callable<String>> tasks = CollectionHelper.arrayList( numberOfIterations );

				for ( int i = 0; i < numberOfIterations; i++ ) {
					tasks.add( () -> executeQueriesForConcurrency( scope ) );
				}

				futures.addAll( executor.invokeAll( tasks ) );

				assertThat( futures.size(), is( numberOfIterations * (f+1) ) );
			}
		}
		finally {
			// make sure all iterations/tasks have completed
			executor.shutdown();
			executor.awaitTermination( 15, TimeUnit.SECONDS );

			while ( ! futures.isEmpty() ) {
				futures.removeIf( future -> future.isCancelled() || future.isDone() );
			}
		}

		// no matter what I have tried above in finally I have been unable to successfully wait until
		// all queries have finished executing.  So I get failures here, although the actual value of 
		// `statistics.getPrepareStatementCount()` varies each time - which is what I base my conclusion
		// that not all queries have completed by the time execution gets here.
		assertThat(
				statistics.getPrepareStatementCount(),
				// 3 queries per iteration
				is( numberOfForks * numberOfIterations * 3 )
		);
	}

	public String executeQueriesForConcurrency(SessionFactoryScope scope) {
		scope.inTransaction(
				session -> {
					final QueryImplementor<Component> query1 = session.createQuery(
							"select e.component from SimpleEntity e where e.component.attribute1 = :param",
							Component.class
					);
					query1.setParameter( "param", "a1" ).list();

					final QueryImplementor<Component> query2 = session.createQuery(
							"select e.component from SimpleEntity e where e.component.attribute1 = :param",
							Component.class
					);
					query2.setParameter( "param", "b1" ).list();
				}
		);

		return null;
	}