What does Dynatrace alert about long garbage-collection times?

The choice indicating that Dynatrace alerts when garbage collection times exceed 40% and suspension exceeds 25% is correct because it aligns with the thresholds set by Dynatrace to effectively manage performance. These specific thresholds reflect a significant impact on application responsiveness and user experience. When garbage collection times are too high, it can lead to increased latency and unresponsiveness, especially in Java applications where garbage collection can pause all threads, affecting the overall performance.

By monitoring these parameters, Dynatrace allows teams to identify performance bottlenecks and take proactive steps to optimize application performance. The combination of a 40% threshold for total time spent in garbage collection and a 25% threshold for suspension time provides a clear indicator of potential issues that require immediate attention to ensure applications run smoothly.