Fork Join pool hangs

The case is that an application hangs infinitely from time to time.

Seems that the bug sits in the following snippet:

ForkJoinPool pool = new ForkJoinPool(1); // parallelism = 1 List<String> entries = ...; pool.submit(() -> { entries.stream().parallel().forEach(entry -> { // An I/O op. ... }); }).get(); 

Thread pool-4-thread-1 that executes the code freezes on get():

"pool-4-thread-1" #35 prio=5 os_prio=0 tid=0x00002b42e4013800 nid=0xb7d1 in Object.wait() [0x00002b427b72f000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(Native Method) at java.util.concurrent.ForkJoinTask.externalInterruptibleAwaitDone(ForkJoinTask.java:367) - locked <0x00000000e08b68b8> (a java.util.concurrent.ForkJoinTask$AdaptedRunnableAction) at java.util.concurrent.ForkJoinTask.get(ForkJoinTask.java:1001) ...other app methods 

One can assume that the task passed to submit() executes too long.

But surprisingly there is no ForkJoinPool-N-worker-N occurrences in the thread dump, so looks like the pool doesn't perform any computations!

How is that possible? If no tasks are executed by the pool, why pool-4-thread-1 thread waits inside get()?

P.S. I know that it's not recommended to execute I/O-related tasks in ForkJoinPool, but still interested in the root of the problem.

Update. When parallelism is set to value greater than 1, no problems are detected.