The Java Mission Control and Java Flight Recorder are relatively new tools that have extended greatly the diagnostics capabilities of the Java platform. They allow collecting an impressive amount of detailed runtime information about the JVM, with minimum performance impact, in a way that would have been hard to imagine a few years ago.
Java Mission Control is basically a set of tools that enables efficient and detailed analysis of the extensive data provided by Java Flight Recorder, which is the entity that lives in the JVM collecting a wide variety of runtime information. Java Flight Recorder used to be tightly integrated with the JRockit JVM, although it’s been bundled with the HotSpot JVM since Java 7 Update 40 release.
There is plenty of information out there about how to use both JMC and JFR in the form of blogs, videos and technical documentation, so I won’t cover that in much detail. The purpose of this article is to give a hint to developers unfamiliar with JFR on how to diagnose performance issues associated to an application flow triggered from the front-end.
One of the most common scenarios that engineers working on applications deployed in WebLogic servers need to deal with is to diagnose a web application with poor performance.
Often, users complain about sluggishness after they click on a specific link of the application or as part of a specific operation. Also, it is common that these performance issues are not constant and happen rather randomly or intermittently.
Normally, getting a full picture of what could have gone wrong, from the front-end to the middle or back-end layers, requires a thorough analysis of all involved components. Depending on the logging capabilities or integrated diagnostic frameworks used by the application, the difficulty of debugging this way may vary, but in general, it becomes time consuming at the least.
If regular logging is only used, the debugger needs to correlate evidences of events and their timestamps in the log files from different components in order to get an idea of any potential bottlenecks.
Also, capturing fairly detailed performance information about an application is usually expensive, and typically requires enabling logging capabilities or using profiling tools based on the JVMPI/JVMTI interfaces, that may have a negative impact in performance as well.
Fortunately, Java Mission Control and Java Flight Recorder have made things much easier for everybody and have become the Holy Grail of Java application profiling, making it feasible to profile applications with virtually no performance degradation, which wasn’t possible a few years ago.
It is possible to integrate WebLogic and the Java Flight Recorder to collect event data from WebLogic containers, through the WebLogic Diagnostic Framework (WLDF). The overhead of enabling JFR and configure WLDF to generate WebLogic Server Diagnostics to be captured by JFR is minimal, and makes it ideal to be used in full-time basis, especially with production environments where it adds the greatest value.
Java Flight Recorder works with the concepts of events, which is the representation of a piece of data related to something that happened at a specific point in time. Read the complete article here.
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