3200% CPU Usage? An Unguarded TreeMap Caused My Nightmare

The author's machine hit 3200% CPU utilization! The culprit? An unprotected `TreeMap`. Concurrent access from multiple threads created a cycle in the red-black tree, causing the program to get stuck in `TreeMap.put()`. Experiments reproduced the issue, revealing that only languages allowing NullPointerException catches could exhibit this problem. Solutions are discussed, highlighting the importance of code reviews, static analysis, and multithreaded tests in preventing such issues.