ConcurrentSkipListSet, add method is failing in Java 8

Question

Pending ConcurrentSkipListSet getting fixed (http://bugs.java.com/bugdatabase/view_bug.do?bug_id=8060435), my brain is failing trying to come up with a work around.

Anyone else having problems with it in Java 8? The add method worked fine in Java 7 but is breaking with Java 8 and causing major havok with the event-system of my audio engine.

I'm thinking of trying to program an alternative. It is important that there be an absolute minimum of blocking occurring. (Am trying to avoid using synchronization.)

The adds are "AudioEvents" (a class I created) ordered by frame number (a long). Adds occur on one thread, and references to the collection occur on the audio thread.

Stuff like this isn't supposed to break between versions.

Answer 1

I am answering my own question, rather than deleting the question, as the information might prove useful for others if a problem with ConcurrentSkipListSet comes up.

My error proved to be a poorly written implementation of Comparable. There are requirements listed in the JavaDoc that are supposed to be enforced which I was careless about.

When the implementation of ConcurrentSkipListSet was revised in Java 8, the hole in my compare resulted in an infinite spin.

The variable frame is a long.

@Override
public int compareTo(AudioEvent other)
{
    if (frame < other.getFrame()) return -1;
    // correct
    if (frame > other.getFrame()) return 1;
    // following is the compare error that WAS here
    // if (frame >= other.getFrame()) return 1;

    return 0;
}

So, a reminder. It is easy to mistakenly jump to conclusions about system code that is relatively mystifying (and ConcurrentSkipListSet qualifies, for me, on that score!). One should first strongly check the code that one wrote that interacts with these "mysterious things."

[Icon for being embarrassed here.]

Answer 2

What you could do is use the source of ConcurrentSkipListSet in OpenJDK 7, which, if you don't have or are too lazy to download, is available on GrepCode or DocJar.