Comments by kjburns1980 (Top 1 by date)

Thank you for your help. Henrik, the problem was occurring on a lambda on a task queue (the code path is pretty straightforward and I wasn't able to find anything suspicious), so it's entirely possible that there may be a problem with the task queue.

I found CopyOnWriteArrayList, and it's only good they say for situations where iteration constitutes 90% of activity on the list. For this purpose, it's at about 65%, which I can live with for now. Plus, if the problem is on the task queue, this will at least take care of things for now so I can move on.

Thank you both for your answers.