In practice, most of Java developers use a combination of these tools to get their performance monitoring needs done at work.

Types of Java Profilers JVM Profilers Great for debugging tasks and tracking down memory leaks Show a large amount of details but relevance may depend on debugging task Features: Tracking all the JVM details (CPU, threads, memory, garbage collection) Track all method calls with memory usage and and allow dive into the call structure Track details of all memory usage with responsible classesobjects CPU sampling feature to track and aggregate CPU time by class and method to help zero in on hot spots Allow to manually run garbage collection and review memory consumption (great way to find classes and processes that are holding on to memory in error) Implementation details: A direct connection to the JVM is used (not favorable in production use) May slow down the application or require downtime (not favorable in production use) Examples: VisualVM, JProfiler, YourKit, Java Mission Control Transaction Profilers There are 2 types of implementations for Transaction Profilers.

Java Profiling Tool Code Into The

Aspect Profilers Use aspect-oriented programming (AOP) to inject code into the start and end of specified methods (the injected code can start a timer and then report the elapsed time when the method finishes); Simple to set up; Need to prior knowledgeguessing on what to profile Agent Profilers Use Java Instrumentation API to inject code into the application; Have in-depth access to application since the code is being rewritten at the bytecode level allowing for any code running in application (written by us or came from 3rd party libraries) to be instrumented; More complicated to write Examples: XRebel, Stackify Prefix APM Tools Great for monitoring applications live in production environments Show a less amount of details (with aggregations and sampling) but mostly the right information which are smartly selected to have high relevance to common performance concerns Implementation details: Use the Java Agent profiler method but with different instrumentation rules to allow them to run without affecting performance in productions Examples: AppDynamics, Stackify Retrace, New Relic, Dynatrace Usage Stats on Profiling Tools According to an interesting survey done by RebelLabs, the following are the pioneering profiling tools used by the companies.

Profiling Tools Usage Stats (Image: Zeroturnaround.com) Also their survey reveals important insights on the performance of each tool when it comes to actual bug finding.

Tools Finding Most Bugs (Image: Zeroturnaround.com) Using Multiple Tools for Finding Bugs (Image: Zeroturnaround.com) A considerable number of these companies have claimed that they are using more than one tool for profiling tasks.

Number of Tools Picked (Image: Zeroturnaround.com) These insights are a solid evidence to state that most of developers use multiple different tools to get their profiling tasks done (some even build in-house tools).

Therefore, since almost all these tools give you the basic features, it is recommended to try what suits your needs and taste.

Using hprof to create a heap dump javac J-agentlib:hprofheapdump Hello.java This consists of the root set as determined by the garbage collector, and an entry for each Java object in the heap that can be reached from the root set.

Using hprof to collect CPU usage javac J-agentlib:hprofcpusamples Hello.java Here the HPROF agent periodically samples the stack of all running threads to record the most frequent active stacktraces.

List of Popular JVM Profilers with GUI Java VisualVM with Visual GC plugin GUI tool shipped with standard JDK (no installationsetup process) Useful for monitoring CPU sampling, memory sampling, run garbage collections, analyze heap errors, take snapshots and more using GUI Can develop new functionalities as plugins Supports local and remote profiling (does not provide support for ssh tunneling, need to configure JMX ports for remote profiling) Can take snapshots of profiling sessions for later analysis Relies on other standalone tools provided in the JDK, such as JConsole, jstat, jstack, jinfo, and jmap Using jvisualvm and jvisualgc 1) Run your Java program with some predefined performance constraints java -Xmx120m -Xms30m -Xmn10m -XX:PermSize20m -XX:MaxPermSiz e20m -XX:UseSerialGC AwesomeJavaProgram 2) Run jvisualvm on terminal to start monitoring JVM Heap Memory usage jvisualvm 3) Now the Java VisualVM application will open up.

Go to Tools Plugins, and install Visual GC plugin (There will be a list of other available plugins too.

Java Profiling Tool Free To Play

You can try them as necessary) Install Visual GC plugin from Java VisualVM application 4) Now feel free to play with the different options and see what you can learn about your application.

Java VisualVM Java VisualGC Connecting VisualVM to Remote JVM by Enabling JMX Remote Ports Not a profiling tool Useful for VisualVM and other profiling tools in remote machines to connect to the local JVM in order to view the CPU utilization, memory sampling, threads etc.

For not-so-large firms, APM Tools can be an overpriced solution to digest (e.g.

Wow, seriously ).

I would recommend you to start with free tools and go for advanced tools only when you have a real use case.

People who performance test their application using multiple profilers tend to find more performance issues than just using one.

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