parallel-letter-frequency: remove failing test (exercism#1766)

FridaTveit · lemoncurry · commit 6fe74b56b344 · 2019-10-04T19:08:32.000+02:00
The last test for the parallel-letter-frequency exercise is now
consistently failing as it runs out of memory. As this exercise is
quite complicated as well and could confused users, we've decided to
remove it.
diff --git a/exercises/parallel-letter-frequency/README.md b/exercises/parallel-letter-frequency/README.md
@@ -9,7 +9,8 @@ list of texts and that employs parallelism.
 
 # Tips
 
-Single-threaded (non-concurrent) solutions can pass all tests [but the last.](https://www.youtube.com/watch?v=mJZZNHekEQw)  Your solution will be tested for concurrency by submitting it as a [Runnable](https://docs.oracle.com/javase/7/docs/api/java/lang/Runnable.html) to an [ExecutorService.](https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ExecutorService.html) Your solution must leverage multiple [Threads](https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html) to pass the final test.
+Single-threaded (non-concurrent) solutions can pass all tests but you should try to implement the solution using parallelism.
+You can do this by using multiple [Threads](https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html).
 
 Java documentation on [parallel streams](https://docs.oracle.com/javase/tutorial/collections/streams/parallelism.html) may provide some help.
 
diff --git a/exercises/parallel-letter-frequency/src/test/java/ParallelLetterFrequencyTest.java b/exercises/parallel-letter-frequency/src/test/java/ParallelLetterFrequencyTest.java
@@ -108,94 +108,4 @@ public void numbersDontCount() {
 
         assertFalse(p.letterCounts().containsKey((int) '1'));
     }
-
-    @Ignore("Remove to run test")
-    @Test
-    public void multipleThreadsGetUsed()
-            throws InterruptedException, ExecutionException {
-
-
-        class MyForkJoinWorkerThread extends ForkJoinWorkerThread {
-
-            boolean wasStarted = false;
-
-            public MyForkJoinWorkerThread(ForkJoinPool pool) {
-                super(pool);
-            }
-
-            @Override
-            public void start() {
-                super.start();
-                this.wasStarted = true;
-            }
-        }
-
-        List<MyForkJoinWorkerThread> allThreads = new ArrayList<>();
-
-        class MyForkJoinThreadFactory implements ForkJoinPool.ForkJoinWorkerThreadFactory {
-            public MyForkJoinThreadFactory() {
-                super();
-            }
-
-            public MyForkJoinWorkerThread newThread(ForkJoinPool pool) {
-                final MyForkJoinWorkerThread worker = new MyForkJoinWorkerThread(pool);
-                worker.setName("Thread number: " + worker.getPoolIndex());
-                allThreads.add(worker);
-                return worker;
-            }
-        }
-
-        MyForkJoinThreadFactory factory = new MyForkJoinThreadFactory();
-        ForkJoinPool multiThreadPool = new ForkJoinPool(4,
-                                                        (ForkJoinPool.ForkJoinWorkerThreadFactory) factory,
-                                                        null,
-                                                        false);
-
-        String input = "abcdefghijklmnopqrstuvwxyz";
-        StringBuilder b = new StringBuilder();
-        for (int i = 1; i < 10000000; i++) {
-            b.append(input);
-        }
-
-        Map<Integer, Integer> expectedOutput = new HashMap<Integer, Integer>() {
-            {
-                put((int) 'a', 10000000);
-                put((int) 'b', 10000000);
-                put((int) 'c', 10000000);
-                put((int) 'd', 10000000);
-                put((int) 'e', 10000000);
-                put((int) 'f', 10000000);
-                put((int) 'g', 10000000);
-                put((int) 'h', 10000000);
-                put((int) 'i', 10000000);
-                put((int) 'j', 10000000);
-                put((int) 'k', 10000000);
-                put((int) 'l', 10000000);
-                put((int) 'm', 10000000);
-                put((int) 'n', 10000000);
-                put((int) 'o', 10000000);
-                put((int) 'p', 10000000);
-                put((int) 'q', 10000000);
-                put((int) 'r', 10000000);
-                put((int) 's', 10000000);
-                put((int) 't', 10000000);
-                put((int) 'u', 10000000);
-                put((int) 'v', 10000000);
-                put((int) 'w', 10000000);
-                put((int) 'x', 10000000);
-                put((int) 'y', 10000000);
-                put((int) 'z', 10000000);
-            }
-        };
-
-        Map<Integer, Integer> multiCounts = multiThreadPool.submit(
-            () -> (new ParallelLetterFrequency(b.toString()).letterCounts())
-        ).get();
-
-        boolean startedThreadCountEqualsPoolSize = allThreads.stream()
-                .filter(thread -> thread.wasStarted)
-                .count() == allThreads.size();
-
-        assertTrue(startedThreadCountEqualsPoolSize);
-    }
 }
