CLion 2018.2 Help

Tuning CLion

Besides the standard options available In the Settings/Preferences dialog (Ctrl+Alt+S), CLion enables you to perform low-level configuration.

Note that this may lead to unexpected problems and may render your CLion installation inoperable. It is strongly recommended that you contact JetBrains Support for instructions regarding the options and values that might help you with whatever issue you are trying to solve.

Configuring JVM options

CLion runs on the Java Virtual Machine (JVM), which has various options that control its performance. The default options used to run CLion are specified in the following file:

<IDE_HOME>\bin\clion64.exe.vmoptions
CLion.app/Contents/bin/clion.vmoptions
<IDE_HOME>/bin/clion64.vmoptions (for the default 64-bit JVM)
<IDE_HOME>/bin/clion.vmoptions (for optional 32-bit JVM)

To configure JVM options:

  • On the Help menu, click Edit Custom VM Options.

CLion creates a copy of the file with JVM options in the configuration directory and opens it in a new editor tab. Any values that you change in this file will override the values from the original default file.

If you do not have write access to the CLion configuration directory, you can add the CLION_VM_OPTIONS (CLION64_VM_OPTIONS on Windows) environment variable to specify the location of the file with JVM options. The values in this file will override the corresponding values from both the original default file and the copy located in the CLion configuration directory.

Common options

The default values of the JVM options should be optimal in most cases. The following are the most commonly modified ones:

OptionDescription
-Xmx Limits the maximum memory heap size that the JVM can allocate for running CLion. Default value depends on the platform. If you are experiencing slowdowns, you may want to increase this value, for example, to set the value to 2048 megabytes, change this option to -Xmx2048m.
-Xms Specifies the initial memory allocated by the JVM for running CLion. Default value depends on the platform. It is usually set to about half of the maximum allowed memory (-Xmx), for example, -Xms1024m.
-XX:NewRatio Specifies the ratio between the size of the young and old generation of the heap. In most cases, a ratio between 2 and 4 is recommended. This will set the size of the young generation to be 1/2 to 1/4 of the old generation correspondingly, which is good when you are often working on one project and only a few files at a time. However, if you are constantly opening new files and switching between several projects, you may need to increase the young generation. In this case, try setting -XX:NewRatio=1, which will make the young generation as large as the old generation, allowing objects to remain in the young generation for longer.

For more information about available JVM options, see the java reference for Windows or macOS/Linux.

Configuring platform properties

CLion enables you to customize various platform-specific properties, such as the path to user-installed plugins and the maximum supported file size. The default properties used to run CLion are specified in the following file:

<IDE_HOME>\bin\idea.properties
CLion.app/Contents/bin/idea.properties
<IDE_HOME>/bin/idea.properties

To configure platform properties:

  • On the Help menu, click Edit Custom Properties.

CLion creates an empty idea.properties file in the configuration directory and opens it in a new editor tab. Any properties that you add to this file will override the corresponding properties in the original default file.

If you do not have write access to the CLion configuration directory, you can add the CLION_PROPERTIES environment variable to specify the location of the idea.properties file. The properties in this file will override the corresponding properties in both the original default file and the one located in the CLion configuration directory.

Common properties

The following properties are commonly changed by users solving specific issues:

  • Location of the default IDE directories may need to be moved, for example, if the user profile drive runs out of space or is located on a slow disk, if the home directory is encrypted (slowing down the IDE) or located on a network drive, if you want to create a portable installation or exclude caches from home directory backups, and so on.

    You can use macros with any property name to insert its value, for example, use ${user.home} (standard Java system property) to specify paths relative to the user's home directory.

    PropertyPath to ...
    idea.config.pathConfiguration directory
    idea.system.pathSystem directory
    idea.plugins.pathPlugins directory
    idea.log.pathLogs directory
  • Limits that can affect performance:

    PropertyDescription
    idea.max.content.load.filesize Maximum size of files (in kilobytes) that CLion is able to open. Working with large files can affect editor performance and increase memory consumption. Default value is 20000.
    idea.max.intellisense.filesize Maximum size of files (in kilobytes) for which CLion provides code assistance. Code assistance for large files can affect editor performance and increase memory consumption. Default value is 2500.
    idea.cycle.buffer Maximum size of the console cyclic buffer (in kilobytes). If the console output size exceeds this value, oldest lines are deleted. To disable the cyclic buffer, set idea.cycle.buffer.size=disabled.
    idea.max.vcs.loaded.size.kb Maximum size (in kilobytes) that CLion loads for showing past file contents when comparing changes. Default value is 20480.

CLion provides a number of other properties that define interaction with the environment (window managers, launchers, file system, and so on). Most of them are like hidden settings (in the sense that they are not evidently exposed), which may need to be enabled or disabled in certain cases. It is strongly recommended to change these properties only after contacting JetBrains Support for assistance.

Selecting the Java runtime for CLion

CLion includes JetBrains Runtime (based on OpenJDK 8), which is used by default.

To switch the Java runtime used to run CLion:

  1. On the Help menu, click Find Action, or press Ctrl+Shift+A.
  2. Find and select the Switch Boot JDK action.
  3. Select the desired JDK and click OK.

The path to the selected runtime is stored in the clion.jdk file in the CLion configuration directory. To revert to the default JetBrains Runtime, you can delete this file, or modify the path to point to another Java runtime.

You can also override the runtime used for CLion by adding the CLION_JDK environment variable with the path to the desired JDK home directory.

Default IDE directories

By default, CLion stores user-specific files (configuration, caches, plugins, logs, and so on) in the user's home directory. However, you can change the location for storing those files, if necessary.

Configuration directory

The CLion configuration directory contains XML files with personal settings, such as, keymaps, color schemes, and so on. It is also the default location for user-defined VM options and platform properties files.

Syntax
%HOMEPATH%\.<product><version>\config
Example
C:\Users\JohnS\.CLion2018.2\config
Syntax
~/Library/Preferences/<product><version>
Example
~/Library/Preferences/CLion2018.2
Syntax
~/.<product><version>/config
Example
~/.CLion2018.2/config

You can change the location of the CLion configuration directory using the idea.config.path property.

You can share your personal IDE settings by copying the files from the configuration directory to corresponding folders on another CLion installation. Make sure that CLion is not running to avoid erasing the copied files when you shut down the IDE. The following table lists subfolders in the CLion configuration directory and corresponding settings that are contained in them:

DirectoryUser settings
codestylesCode style schemes
colorsCustomized editor color and font schemes
fileTemplatesUser-defined file templates which pertain to the entire CLion workspace
filetypesUser-defined file types
inspectionCode inspection profiles
keymapsCustomized keyboard shortcuts
optionsVarious options, for example, feature usage statistics and macros
scratchesScratch files and buffers
templatesUser-defined live templates
toolsConfiguration files for user-defined external tools
shelfShelved changes

System directory

The CLion system directory contains caches and local history files.

Syntax
%HOMEPATH%\.<product><version>\system
Example
C:\Users\JohnS\.CLion2018.2\system
Syntax
~/Library/Caches/<product><version>
Example
~/Library/Caches/CLion2018.2
Syntax
~/.<product><version>/system
Example
~/.CLion2018.2/system

You can change the location of the CLion system directory using the idea.system.path property.

Plugins directory

The CLion plugins directory contains user-installed plugins.

Syntax
%HOMEPATH%\.<product><version>\config\plugins
Example
C:\Users\JohnS\.CLion2018.2\config\plugins
Syntax
~/Library/Application Support/<product><version>
Example
~/Library/Application Support/CLion2018.2
Syntax
~/.<product><version>/config/plugins
Example
~/.CLion2018.2/config/plugins

You can change the location of the CLion plugins directory using the idea.plugins.path property.

Logs directory

The CLion logs directory contains product logs and thread dumps.

Syntax
%HOMEPATH%\.<product><version>\system\log
Example
C:\Users\JohnS\.CLion2018.2\system\log
Syntax
~/Library/Logs/<product><version>
Example
~/Library/Logs/CLion2018.2
Syntax
~/.<product><version>/system/log
Example
~/.CLion2018.2/system/log

You can change the location of the CLion logs directory using the idea.log.path property.

Adjusting CPU Cores Number

You can adjust the number of CPU cores to be used by the IDE when running the active tasks (e.g indexing header files, updating symbols, etc.) in order to keep the performance properly balanced between CLion and other applications running on your machine.

To set up the number of CPU cores:

  1. Go to the Help | Find Action main menu option or hit Ctrl+Shift+A. In the dialog that opens start typing Registry:
    cl callRegistry
    Select Registry from the list of suggested options.
  2. In this dialog, start typing cidr.indexer.thread.count. The IDE highlights the corresponding key.
    cl registryCPUCore
    Click the Value field of the highlighted string and enter the desired number of CPU cores assuming the following:
    • Negative value N means that the actual number of CPU cores will be reduced by N to determine how many cores will be used. For example, for 8 cores CPU the value -1 means, that 7 cores shall be used.
    • Zero value means that every available core shall be used.
    • Positive value determines the cores number to be used directly.
Last modified: 18 September 2018