@@unknown MC-63590 is the end result caused by the excessive mob spawning described above. This bug focuses on the root cause. To me the crash is probably preferable to letting mob spawn continue out of control. In either case the server is rendered unusable as a result of the underlying mob spawn issue which this bug seeks to address. This is not a dupe of the crash bug.
@@unknown I understand why the watchdog functions as it does. I also understand that this is related to the user's decision to allow his mob spawner to run out of control. The reason why I have filed this bug is because in the past mob generation appeared to be capped but that no longer seems to be the case. The player expected Minecraft to stop spawning mobs as it has always done in the past but it failed to do so. I see no indication that this cap has been officially removed so I must assume that it is a bug until ruled otherwise by Mojang. I appreciate your help but your suggestion still does not address the root cause.