Debugging

• Debugging

  • From bug in a running application in production

  • From a failing build

  • From test not passing correctly

  • Within container or application is running

  • Debugging Issues With memory or high requests

From bug in a running application in production

From a failing build

From test not passing correctly

Within container or application is running

Debugging Issues With memory or high requests

• Need metrics to cover a long period

• Need to see metrics from the jvm

  • Threads in use

    • This should not be increasing continuously, but go and down to show that the threads are being closed

  • Heap memory

    • Should show the memory being garbaged collected

• Need time taken to return a response

  • Is it just one endpoint, or all end points?

  • Is it one instance of the app or several or all?

  • Does it increase in latency? then drops? Then increase again

• If cannot get metric needed, maybe way of getting metrics is down, need to check the metrics trend before it stopped producing metrics

• Get the heap dump

  • jps - to get the PID

  • jstack <pid> - to get the trace

  • Need to get the full trace, in a file

  • Go to intellij, and copy the file contents into the analyze -> analyze stack trace and look at the info.

    • Look for any info that might appear in your app ie thread names that are used in your app or classes in your app

• Get the problem on your local box. Run the app, get trace, compare to the trace from the environment that had the problem.

  • use an end to end test and debug

• Maybe the problem is a one off, and looking at the trend, wiil show this