It is known for its effective memory management and for identifying and eliminating memory leaks. It has been a popular IDE for java programmers as well to perform various vital operations related to heap calculation and analysis. The user interface is simple and clearly shows the heap memory with filters like Used memory, Total memory, and Free memory available using graphs.
JProbe is an integrated toolkit consisting of various java profiler tools by Quest Software. It is developed to diagnose and eliminate any inefficiencies or errors in Java applications. JProbe Profiler integrates a visual Graph interface with its data collection technology to provide highly accurate performance data to help developers identify any performance problems present in the code.
JProbe profiler is different because it helps java developers understand the cause of the error or any performance issues in the application. It is used to detect and eliminate any memory leaks present and improves application performance by increasing memory usage and reducing garbage collection.
It handles all the thread problems such as deadlocks, thread stalls, and race conditions by identifying any actual or potential threading problems that can be a threat to application data. It assists developers and quality assurance engineers in locating any unexecuted code in the application, making it a useful feature for unit testing and user acceptance test runs.
Some other paid profilers also lie in a similar price range. All the best Java profilers from well-known companies have been so expensive that they are not affordable to small and mid-tier companies, and only the largest enterprises can afford them. Thanks to the open-source community, some free alternatives can perform the job to a great extent. In current times, an efficient java profiler has become a necessity for java developers that helps them in performing all the monitoring to improve the performance of their applications in the development phase.
We have discussed profiling and some of the best Java Profilers. Choosing the most suitable profiler solely depends on the developers and the level of analysis and information required by the development team. If you require a profiler for a small project like a small business or a local office management system, profiling will be relatively very straightforward, so a standard open-source profiler can be used to do the job. If you are developing a web application that includes hefty features like a tracking system and would have an extensive user base where it will be accessed by thousands of users in real-time, you will need some more advanced profiling tools.
Find a broad range of job listings on our careers portal that allows you to use Java Profiler just the way you want. Shaharyar Lalani is a developer with a strong interest in business analysis, project management, and UX design.
CPU flame graph is an efficient way to visualize application performance, which allows to find performance bottlenecks quickly and easily. Profiler shows slow SQL queries and web requests, to help you find performance bottlenecks.
Profiler visualizes object heap and allows traversing of object graph in any direction. Objects properties are visualized in convenient form. Profiler chooses the best way to show you a content of a HashMap or a String value. For each object you can see how much memory it retains, and what happens when particular reference in object graph does not exist. This saves your time, and lets to estimate the expected memory leak fix without changing the code.
Track how changes in the code affect the performance of your application. YourKit Java Profiler can compare performance and memory snapshots and export comparison reports in different formats.
Profiler knows a lot about typical issues in Java applications and automatically finds them. You can easily find leaked webapps, duplicated objects, non-closed SQL statements and streams.
YourKit Java Profiler visualizes threads activity. Relative time is measured as a percentage of the total execution time that the target JVM spends running garbage collection with all application threads suspended.
Surviving generations displays the number of different ages for all objects allocated on the JVM heap since the moment the Profiler was attached. During a profiling session, you can view detailed information about application thread activity in the Threads window.
Start monitoring thread activity at any time during a profiling session by opening the Threads tab and clicking Threads. By default, application thread activity is not monitored until invoked. To open the Threads window during a profiling session:. Click Threads in the Profiler window.
If you want to monitor threads from application startup, select Enable Threads Monitoring when you start the profiling session. For more information configuring profiling tasks, see Section 8. The Live Results window displays the live results of the running profiling session. Use the toolbar and context menus to work with the results displayed in the Live Results window. To open the Live Results window, do one of the following during a profiling session:.
Table Live Results Commands. Updates results at short intervals when enabled default state. When disabled, click Update Results Now to update the results. Exports the displayed results as a. Click on the respective column header to sort the results in the table. Right-click result entries in the table to choose commands from the context menu. The results that are displayed and the context menu items that are available depend upon the profiling task that is running.
If you are profiling application performance and instrumenting methods in your profiling session, click DrillDown to open the DrillDown Window to view a graphic overview of the information in the Live Results window and explore the profiled methods according to general predefined categories.
The percentage of methods in each predefined category is displayed below the graph. Click on a category area displayed in the graph to drill down to view methods in that category.
You can use this to filter the list of methods displayed in the Live Results window. Click on a method in the Live Results window to view the category for that method in the DrillDown window.
If you want to examine profiling data captured at a specific time during execution, you can take a snapshot of the data. To refine the profiling results, you can set filters for a profiling session.
In the Live Results window and in result snapshots you can use the filter box located below the displayed results to filter the results by name.
In snapshots, the filter box is available in the HotSpots and Combined tabs in CPU snapshots, and in the Memory tab in memory snapshots. Click the arrow to the right of the filter box to see and select previous filter terms. To restore the full unfiltered results, click Clear Filter to the right of the filter box. The Captured Results windows show profiling data at a certain point in time during the profiling session.
You can capture results at any time during a profiling session and save the results to your project or local system. It is not necessary to run a profiling session to view saved captured results. Displays the captured results of a profiling session. The data contained in the snapshot depends upon the profiling task that is running when the snapshot is taken. Displays the current results in a results window.
Click Save Current View to Image in the toolbar to save a. A results snapshot captures profiling data at a specific point in time. You can explore snapshots using the toolbar in the Snapshot window and by filtering the displayed results. You can also right-click a result and select additional commands in the context menu. When a snapshot is open, you can use the toolbar at the top of the snapshot to help you work with the snapshot. The tools in the toolbar enable you to save snapshots, refine the display and search for terms within the results.
The following table describes the items in the snapshot toolbar. Table Snapshot Commands. Saves the snapshot to your project. Saved snapshot files are visible in the Saved Snapshots section of the Profiler window. Compares two saved snapshots. When you click the button in the toolbar of an open snapshot you are prompted to choose a snapshot file to compare to the open snapshot. In the Saved Snapshots section of the Profiler window, select your project from the drop-down list. When you are locating snapshots in the file browser, the snapshot file type for memory snapshots and CPU snapshots is indicated by.
You cannot identify the type of snapshot by the file name in the file browser if you used the default names that were generated by the IDE when you saved the snapshots. When choosing the snapshots that you want to compare, make sure the snapshots are of the same type and contain similar details based on the options that were selected for the profiling session when the snapshot was taken. The comparison that is displayed depends upon the data that is contained in the snapshots.
The data that is captured in the snapshot depends upon the options that were selected for the profiling session. The CPU Snapshot Comparison window displays a table showing the method call chain and the time spent and the number of invocations for executing threads and methods in each context.
The IDE compares the two CPU snapshots and displays the differences between the two snapshot in the number of invocations and the amount of time spent in invocations. Click Show or Hide Result Columns to modify the columns that are displayed in the table. Right-click in the row for a class and choose Go To Source to load the source. Right-click in the row for a method and choosing Add to Instrumentation Roots to add a method as a profiling root method.
Filter the list by the name of the method, class or package by typing the filter criteria in the Filter field at the bottom of the window and clicking the filter icon to selecting a filter option. The Memory Snapshot Comparison window displays a table with details about the number of object instances and the amount of memory occupied by the objects at the time the snapshots were taken.
The IDE compares the two snapshot and for each object displays the changes that occurred between the snapshots. Load the source. Filter the list by the class name by typing the filter criteria in the Class Name Filter at the bottom of the window and clicking the filter icon to selecting a filter option.
You can load and browse any heap dump saved on your local system. It is not necessary to run a profiling session to load and browse a heap dump. The default location for heap dump files the file name is appended with. The HeapWalker enables you to evaluate Java heap contents and search for memory leaks. Use the HeapWalker to view the following information. List of classes present on the heap. For each class you can see the number of instances of that class and total size of all instances.
List of instances of each class. You can see individual instances and their size size of instances of the same class varies only for arrays. Fields of each instance or class. You can browse static fields to identify individual instances by field values and determine dependencies among them. References to each instance. You can browse instances or classes holding reference to a particular instance to find unnecessary references and discover memory leaks.
When the heap dump is loaded and open in the Heap window, use the following tabs to view information about the heap dump:. This tab displays general information about the heap dump such as total numbers of classes, instances. The Summary tab also provides you with information about the environment and system properties of the machine where the heap dump was taken.
This tab displays a list of classes with information about the number of instances of the class and total size of the instances. You can use the Static Fields and Classes tab to modify the information that is displayed in the tab.
Click Static Fields at the top of the Classes tab to view the static fields of the selected class. Use the Class Name Filter to limit the classes that are displayed. You can double-click any class in the list to view the instances of that class in the Instances tab.
Alternatively, you can right-click a class and choose Show in Instances View. This tab displays the instances for a class that you select in the Classes tab. For each instance, you can do the following:. If you click Compute retained size at the top of the Instances tab the IDE calculates and displays the size of each instance and the total size for all the instances of the selected class.
Click Instances , Fields , or References in the toolbar to hide or reveal the individual windows. OQL Console. Use any of the sample OQL queries or create a query to filter and select heap data to locate the information that you want from the Java heap. After you choose or write a query, run the query against the Java heap and view the results. Compare two heap dumps to view the differences between two heap snapshots that were taken at different times.
It is not necessary to run a profiling session to compare heap dumps. Alternatively, you can open heap dump snapshots from the Profiler Control Panel if an open project has snapshots associated with the project. Click Compare with another heap dump at the top of the Classes tab. Select a heap dump that is saved in your project or select From File and click Browse to locate a heap dump that is saved outside of your project on your local system.
Click reset view at the top of the Heap window to display the initial heap dump. While pre-defined queries such as "show all instances of class X" are already supported by the tool, OQL adds more flexibility. OQL is based on the JavaScript expression language. You can use any of the sample OQL queries or create a query and then run the query against the Java heap and view the results.
Alternatively, you can select a query in the Saved Queries pane and click Open. Skip Headers. This chapter contains the following sections: Section 8. Note: The JUnit 4. Note: Depending on the version of the unit testing framework you are using, the name of the test class is not required to end with Test. To run tests for an entire project: Select any node or file in the project you want to test in the Projects or Files window. The IDE executes all of the project's tests.
To run a test for a single class: Select the node of the class for which you want to run a test in the Projects or Files window. To run a single test method: Run the test class or suite containing the test method. To run a single test method the method must be listed in the Test Results window.
The textual output from the unit tests themselves is displayed in the right pane of the window. To debug a unit test: Place your breakpoints in your test class. Select the node for the class whose test you wish to debug. To edit unit test settings as you create tests: Right-click the sources for which you wish to create tests.
Select a unit test framework. In the Create Tests dialog box, select the Code Generation options you require for the tests. The IDE creates the tests with the specified options. To edit the classpath for compiling or running tests: Right-click the project's Test Libraries node and choose one of the following: Add Project.
A JAR file or folder somewhere on your system. The selected file must have a main method. Note: Before you can use the profiler in the IDE, you must calibrate the profiler. To profile an individual project: Right-click a project in the Projects window and choose Profile.
Select a profiling task in the Select Profiling Task dialog box. Specify any options for the task. Click Run. To profile a specific class: In the Projects window, select the class that you want to profile.
The following could affect system performance: Any hardware upgrade Any significant change or upgrade of the operating system An upgrade of the Java platform used for profiling To calibrate the IDE to the local system: Close any other programs that are running.
Choose the Java Platform to be used for profiling and click OK. Do not share calibration data between various computers or systems. Analyze CPU Performance Choose this to obtain detailed data on application performance, including the time to execute methods and the number of times the method is invoked. Analyze Memory Usage Choose this to obtain detailed data on object allocation and garbage collection. Specify the options for the task in the right pane of the dialog box.
For example, you might want to use the attach mode in the following cases: Your application needs to be started from the command line or uses a complex launch script You want to obtain profiling data on the startup of the application or target JVM You want to profile the application without restarting the application You must use the attach mode in the following cases: You want to profile an application running on a remote JVM, such as a remote application server You want to profile a Java EE or web application and the target server is not Tomcat, GlassFish, WebLogic or JBoss The Attach mode enables you to attach the profiling tool to an application that is already running, or just about to start on a local or remote machine.
Specify the location of the application and the connection method. Table provides an overview of the attach modes: Table Attach Modes Attach Mode Description Local Dynamic Use this mode if you want to obtain profiling data on a local application. Local Direct Use this mode if you want to obtain profiling data on the startup of a local application.
Remote Direct Use this mode if you want to obtain profiling data on an application running on a remote JVM.
For example, you may want to use the attach mode in the following cases: Your application needs to be started from the command line or uses a complex launch script. You want to obtain profiling data on the startup of the application or target JVM.
When you configure the settings for attaching to a local application, you can choose from the following attachment modes: Dynamic. Select the target application from the Attach To drop-down list at the top of the dialog box. Select Local as the Attach Method. In the Attach Profiler dialog box, select a profiling task and any options. Click Attach. Select a new profiling command and adjust any settings. The target application is instrumented again without starting or stopping the application.
In the Attach Settings dialog box, select Remote as the Target option. Click OK in the Attach Settings dialog box. Start the remote application. Select a profiling task and any profiling options. Click Attach in the Attach Profiler dialog box. After the IDE is attached to the remote application you can do the following: Detach from the remote application. Modify the profiling session. Table identifies the startup scripts and the parameters that must be modified to specify the paths to the JDK and the profiler libraries: Table Startup Scripts Server File Modification Tomcat 7 catalina.
Before profiling your free-form project, be aware of the following conditions: The project output must be set before you can profile a free-form application. A snapshot differs from live profiling results in the following ways: Snapshots can be examined when no profiling session is running.
Snapshots contain a more detailed record of profiling data than live results. Snapshots can be easily compared. Perform the following steps to take a snapshot manually: Start a profiling session. To take a snapshot using a profiling point: Open the source file containing the code where you want to place the profiling point. Right-click in the line of code and choose Insert Profiling Point.
If you use a profiling point to take a snapshot, you can choose from the following snapshot options: Take Snapshot. To save a snapshot; Click Save to Project in the snapshot toolbar. You can also use the Options window to configure the IDE behavior when taking a snapshot. To select a configuration or create a custom configuration from a snapshot: Right-click a method name in a CPU snapshot and select Add to Instrumentation Roots in the context menu to open this window.
Note: To take a heap dump, the application must be running on a version of JDK 1. To take a heap dump manually: Start a profiling session. Select either Exclusive or Inclusive as the filter type. Type or modify the filter values and click OK. If you want to use a filter more than once, you can create a custom filter set. Examples include garbage collection, which tells you the start and end time of garbage collection, monitor wait which tells you how long a thread waited on an object, and monitor contended, which tells you how long a thread was waiting on a lock to be released.
In addition to the generated events, the JVM also has profiling functions that return data about its internal state. This internal state data is queried periodically by the profiler in a process known as sampling and the sampling period is how often the functions get called to fetch the data.
For example, every 20 milliseconds. When analyzing application performance, there are a number of profiling activities that are commonly performed by programmers and analysts. These include CPU profiling, memory profiling, and thread profiling. CPU profiling is primarily concerned with the frequency and length of time of method execution. These are commonly referred to as "hot methods.
There are two ways in which CPU profilers get method execution information; by sampling or by instrumentation.
Sampling profilers work by periodically querying the JVM for all the running threads and getting the stack trace for each thread. It then determines what method each thread was executing when the sample was taken and compares the samples to determine how much time was spent in that method. Profiling by sampling has the least amount of overhead and is, therefore, suitable for production use.
However, because it's an indirect way of measuring method execution, it can be error-prone or inaccurate depending on the execution flow of the application and how often the profiler samples.
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