Most applications allocate objects during startup and then allocate temporary objects that are periodically garbage collected. This increase is an indication that there is a memory leak. To identify a possible memory leak, review the following elements in the recording:įirst, notice that the lastKnownHeapUsage element in the Old Object Sample events is increasing over time, from 63.9 MB in the first event in the example to 121.7 MB in the last event. Jfr print -events OldObjectSample pid16276.jfr The following example shows the command and an example of the output from a recording for an application with the pid 16276: When you have a recording, use the jfr tool located in the java-home/bin directory to print Old Object Sample events that contain information about potential memory leaks. $ jcmd pid JFR.dump filename=recording.jfr path-to-gc-roots=true An alternative way to get a recording is to dump it before the application runs out of memory using the jcmd tool, as shown in the following example: When the JVM runs out of memory and exits due to a error, a recording with the prefix hs_oom_pid is often, but not always, written to the directory in which the JVM was started. Start a recording when the application is started using the java command as shown in the following example: The overhead of JFR is very low, less than 1%, and it has been designed to be safe to have always on in production. To detect a memory leak, JFR must be running at the time that the leak occurs. This information can be used to identify memory leaks. Java Flight Recorder (JFR) records detailed information about the Java runtime and the Java application running on the Java runtime. Here is a sample figure of a recording, which shows heap size issue: To detect a memory leak focus on the Live Objects section of the page. Look at the Automated Analysis Results page. Once the recording is complete, the recording file (. Before starting a flight recording, make sure that the option Object Types + Allocation Stack Traces + Path to GC Root is selected from the Memory Leak Detection setting. Open JMC and start a Time fixed recording (profiling recording) for an hour. Open the MBean Browser tab and look for the GarbageCollectorAggregator MBean under. To inspect the live set, open JMC and connect to a JVM using the Java Management console (JMX). The live set is the amount of Java heap that is used after an old collection (all objects that are not live) and have been garbage collected. Watch if the live set of your application is increasing over time. However, memory leaks can be detected early, even before such problems occur, by analyzing Java Flight recordings. Eventually, OutOfmemoryErrors may be seen. A typical symptom could be the application becoming slower after running for a long time due to frequent garbage collections. NET Profiler.Detecting a slow memory leak can be hard. Take a look at YourKit's leading software products: YourKit Java Profiler and YourKit. YourKit, LLC is creator of innovative and intelligent tools for profiling Java and. YourKit is kindly supporting open source projects with its full-featured Java Profiler. is the world's largest Open Source software development web site, hosting more than 230,000 projects and over 2,000,000 registered users with a centralized resource for managing projects, issues, communications, and code. The Software Process Dashboard Project Team also extends its appreciation to the following vendors, who donate free software licenses and services to open source projects, including the Process Dashboard: We feel that this is the least we can do to thank the SEI for developing and distributing these remarkable processes.īackground: What is the PSP? What is the TSP? Why build a tool?įunctionality: For Individuals For Teams Downloadįunding for the project is provided by many generous sponsors who purchase support, consulting services, and server licenses from Tuma Solutions, LLC. We therefore aim to develop a world-class tool under the open-source model, and distribute it freely to anyone using the PSP and/or TSP. We feel that a freely available, powerful support tool could help to remove one of the most significant barriers to PSP / TSP adoption. We feel that the PSP and the TSP are remarkable technologies that can change the face of the software industry, and we share the SEI's zeal to promote their widespread use. The Software Process Dashboard Project is an open-source initiative to create a PSP (SM) / TSP (SM) support tool.
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