What methods and tools can be used to diagnose the causes of stopping or slowing down a Java server?

To diagnose the causes of Java server stoppages or slowdowns, the following methods and tools can be used:

• Application and server logs — the primary source of information about crashes and errors.
• JVM monitoring and profiling:
  • jconsole or jvisualvm — for monitoring memory usage, CPU, threads.
  • jstack — for capturing thread dumps and analyzing deadlocks.
  • jmap — for creating heap dumps and analyzing leaks.
• Garbage Collection (GC) logs — help understand if the server is slowed down due to frequent or long garbage collections.
• Profilers (e.g., YourKit, VisualVM, Java Flight Recorder) — for in-depth performance analysis and identifying bottlenecks.
• System resource monitoring (CPU, memory, disk, network) using OS tools (top, vmstat, iostat) or specialized monitoring systems (Prometheus, Grafana).

Using these tools, you can identify the causes of slowdown — such as thread blocking, memory leaks, excessive GC load, or external resource issues.