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Profile unit tests

Last modified: 31 July 2022

warning

Profiling of unit tests available with the following limitations:

  • Windows: .NET Framework 4.0+, .NET Core 3.0+, .NET 5+, Mono 5.10+ (Timeline only).

  • Linux: .NET Core 3.0+, .NET 5+, Mono 5.10+ (Timeline only).

  • macOS: .NET 5+, Mono 5.10+ (Timeline only).

Along with applications, dotTrace lets you profile unit tests. The profiling workflow looks as follows:

  1. Decide which profiling configuration you will use.

  2. Run the profiling session and get snapshots.

  3. Analyze the collected snapshots.

Run the session and get snapshots

Start a session and get snapshots

  1. Do one of the following:

    • Open the Unit Tests window, select unit tests you want to profile, and in the Run Selected Unit Tests list, choose Profile Selected Unit Tests or choose Tests | Profile Selected Unit Tests in the main menu.

      Profile unit tests

    • In the code editor, open the menu in the gutter for a desired unit test or test class and select Profile.

      Profile Unit Tests

  2. In the list of profiling configurations, select:

    Profiling configurations

    Once the profiling is started, you will see the dotTrace Profiler tool window opened on the Profiling tab with the profiling controller inside.

  3. When profiling unit tests, you don't have to manually control the profiling session (get snapshots and finish the session). dotTrace will automatically take a performance snapshot once a unit test session is over. The collected snapshot will be added to the list of snapshots inside the dotTrace Profiler window.

Analyzing collected snapshots

For more details on how to analyze performance snapshots, refer to Analyze profiling results.

Analyze a snapshot

  1. On the All Snapshots tab of the dotTrace Profiler tool window, select the snapshot you want to analyze.

  2. Analyze the collected data using one of the views:

    • Call Tree: a "classic" call tree that shows you all method calls in all threads. Each top-level node represents a top-level function which was executed by a certain thread. Use this view to quickly get down to actual application activity. Learn more

    • Top Methods: the best place to start when analyzing application performance. It is a simple plain list of methods with the highest execution time. Note that you can reduce the system functions "noise" by excluding them from the list using the Hide system functions toggle: if enabled, method's execution time is calculated as a sum of method's own time and the time of all child system methods (down to the next user method in the stack). Learn more

  3. Once the suspicious method is found, press F4 or select Jump to Source from the context menu. Rider will navigate you right to the method's source code.

About profiling configurations

  • Before starting a profiling session, you must decide which profiling configuration you will use. Typically, you decide between

  • The profiling configuration specifies profiling session settings like which profiling type will be used, whether child processes must be profiled, and so on.

  • The profiling target is a unit test runner that runs selected tests.

Create a custom profiling configuration

  1. In the menu, choose Run | Switch Profiling Configuration | Edit Configurations.

  2. In the opened Profiling Configurations window, click App resharper structural search add pattern to add a new profiling configuration.

  3. In the list, select one of the profiling types:

    Timeline

    Collects temporal data about thread states, application events, and other multi-threading data. Based on Event Tracing for Windows (ETW). Supports native profiling.

    Recommended for most cases. Especially, for analyzing multithreaded apps. Use it, for example, to determine the cause of UI freezes, excessive garbage collections, uneven workload distribution, insufficient I/O, and so on.

    If you want to create a configuration for profiling Mono or Unity applications, select Timeline (Mono) or Timeline (Unity) correspondingly.

    Sampling

    Accurate time measurement, number of calls is not measured.

    Recommended for most cases. Ideal when you look for performance issues in your app for the first time.

    On macOS and Linux, if you want to profile an application targeting .NET Core 3.0 or earlier, select Sampling (.NET Core 3.0 or earlier). Note that because of .NET Core limitations, you might have issues: the profiled application may hang or crash. Projects targeting .NET Core 3.1 (or later) can be profiled without any issues.

    Tracing

    Accurate calls count measurement, time measurement may be inaccurate due to profiling overhead.

    When sampling data is not enough. For example, for analyzing algorithm complexity (when info about number of calls is more valuable than call time values).

    Line-by-line

    Windows only.

    Each line of code is measured, call time values are inaccurate due to huge profiler overhead.

    For advanced use cases only. For example, when you already know what function causes issues and want to analyze each line of it.

  4. Specify configuration Name and other profiling options:

    Control profiling manually

    Enables you to control profiling manually via the profiler controls. For example, to take a snapshot, you will have to click Get Snapshot.

    Collect profiling data from start

    This setting is ignored when profiling unit tests.

    Control profiling via API

    Enables you to control profiling directly from the code of the profiled application. For example, to take a snapshot in the exact point of your code. Learn more about using the API in the dotTrace documentation.

    Profile child processes

    If selected, dotTrace will profile not only the main app process but the processes it runs as well.

    Profile .NET 5+ child processes

    (Timeline on macOS and Linux)

    If selected, dotTrace will profile not only the main app process but the processes it runs as well. Only .NET 5 and later processes are supported.

    Time measurement

    (Sampling, Tracing on Windows, Line-by-line)

    This option defines how dotTrace must calculate calls time. Typically, this is a choice between whether dotTrace should calculate time when a thread is not working or should not. For more details, refer to dotTrace documentation.

    Real time (performance counter)

    Recommended. dotTrace calculates the overall real time passed between method entry and exit. This time does not depend on app threads states. Time is calculated using system performance counter.

    Real time (CPU instruction)

    dotTrace calculates the overall real time passed between method entry and exit. This time does not depend on app threads states. Time is calculated using the CPU register.

    Thread time

    dotTrace calculates only the time when a certain thread is running. The time when the thread is waiting or sleeping is not included in calculation.

    Thread cycle time

    dotTrace calculates only the time when a certain thread is running. The time when the thread is waiting or sleeping is not included in calculation. Time is calculated using the CPU register.

    Enable inlining

    (Tracing, Line-by-line)

    Clear this option if you want dotTrace to turn off JIT-inlining and get call stacks that closely resemble the structure of application's source code.

    High accuracy

    (Tracing, Line-by-line)

    If selected, dotTrace will take into account time spent in profiler itself by taking more time samples.

    Enable native profiling

    (Timeline, Unity/Mono on Windows)

    If selected, dotTrace will collect native call stack data. The resulting snapshot will contain both managed and native call stacks. This profiling option may be helpful for finding performance issues in Unity games.

    Collect native allocations

    (Timeline on Windows)

    If selected, dotTrace will collect information about all memory allocations the profiled application does in the native (unmanaged) heap. To be able to select this option, you must have Windows Performance Toolkit installed on your computer.

    Collect TPL events

    (Timeline)

    If selected, profiling performance may be affected but dotTrace will collect Task Parallel Library (TPL) data. If cleared, there will be no Task nodes in Call Tree and async call nodes will be shown without their await and continuations parts.

    Clear this option in case your application does not use multitasking or you do not need this info.

    tip

    Learn more about how dotTrace works with asynchronous code in the dotTrace documentation.

    Collect debug output

    (Timeline on Windows)

    If selected, dotTrace will collect information about all messages the profiled application sends to the debug output.

    Download symbol files

    (Timeline on Windows)

    PDB files (or symbol files) let you see native functions in the call tree. This is relevant for native applications and managed applications that call native code. If you select Download symbol files, JetBrains Rider will try downloading PDB files from remote servers right after you get a snapshot. Note that this may take a significant amount of time depending on file size.

    By default, JetBrains Rider looks for PDB files in the locations specified in the _NT_SYMBOL_PATH environment variable. Alternatively, you can specify custom local or remote locations using the configure symbol servers link.