GoLand 2020.2 Help

Breakpoints

Breakpoints are special markers that suspend program execution at a specific point. This lets you examine the program state and behavior. Breakpoints can be simple (for example, suspending the program on reaching some line of code) or involve more complex logic (checking against additional conditions, writing log messages, and so on).

Once set, a breakpoint remains in your project until you remove it explicitly, except for temporary breakpoints).

Types of breakpoints

The following types of breakpoints are available in GoLand:

  • Line breakpoints: suspend the program upon reaching the line of code where the breakpoint was set. This type of breakpoints can be set on any executable line of code.

  • Exception breakpoints: suspend the program when subclasses are thrown. panic() is thrown.

Set breakpoints

Set line breakpoints

  • Click the gutter at the executable line of code where you want to set the breakpoint. Alternatively, place the caret at the line and press Ctrl+F8.

    Debug a line breakpoint

Set exception breakpoints

  1. Click View Breakpoints View Breakpoints button in the left part of the Debug tool window or press Ctrl+Shift+F8.

  2. In the Breakpoints dialog, select Go error breakpoint or JavaScript Exception Breakpoint.

    Create an exception breakpoint

Manage breakpoints

Remove breakpoints

  • For non-exception breakpoints: click the breakpoint in the gutter.

  • For all breakpoints: from the main menu, select Run | View Breakpoints Ctrl+Shift+F8, select the breakpoint, and click Remove Delete.

To avoid accidentally removing a breakpoint and losing its parameters, you can choose to remove breakpoints by dragging them to the editor or clicking the middle mouse button. To do this, go to Settings/Preferences | Build, Execution, Deployment | Debugger and select Drag to the editor or click with middle mouse button. Clicking a breakpoint will then enable or disable it.

Mute breakpoints

If you don't need to stop at your breakpoints for some time, you can mute them. This allows you to resume normal program operation without leaving the debugger session. After that, you can unmute breakpoints and continue debugging.

  • Click the Mute Breakpoints button Mute Breakpoints button in the toolbar of the Debug tool window.

Enable/disable breakpoints

When you remove a breakpoint, its internal configuration is lost. To temporarily turn an individual breakpoint off without losing its parameters, you can disable it:

  • For non-exception breakpoints: right-click it and set the Enabled option as required. You can also toggle them with the middle mouse button if removing breakpoints is not assigned to it.

  • For all breakpoints: click View Breakpoints Ctrl+Shift+F8 and check/uncheck the breakpoint on the list.

Move/copy breakpoints

  • To move a breakpoint, drag it to another line.

  • To copy a breakpoint, hold Ctrl and drag a breakpoint to another line. This creates a breakpoint with the same parameters at the destination.

Configure breakpoints' properties

Depending on the breakpoint type, you can configure additional properties which allow you to tailor its operation for specific needs. The most used options are available via intentions.

  • To access breakpoint intentions, place the caret at the line with the breakpoint and press Alt+Enter. Use this option when you need to quickly configure basic breakpoint properties.

  • To access the full list of properties, right-click the breakpoint and click More or press Ctrl+Shift+F8. Use this option for a bird's eye view of all breakpoints and full control over their configuration.

Intentions reference

Intention

Description

Remove breakpoint

Removes the breakpoint at the selected line.

Disable breakpoint

Disables the breakpoint at the selected line.

Edit breakpoint

Opens a dialog with the most used breakpoint properties. For more properties, click More or press Ctrl+Shift+F8.

Breakpoints' properties

Enabled

Clear the checkbox to temporarily disable a breakpoint without removing it from the project. Disabled breakpoints are skipped during stepping.

You can configure GoLand to enable/disable breakpoints on clicking rather than removing them altogether. To do this, go to Settings/Preferences | Build, Execution, Deployment | Debugger and set the Remove breakpoint option to Drag to the editor or click with middle mouse button.

Suspend

Specifies whether to pause the program execution when the breakpoint is hit.

Non-suspending breakpoints are useful when you need to log some expression without pausing the program (for example, when you need to know how many times a method was called) or if you need to create a master breakpoint that will enable dependent breakpoints when hit.

Condition

This option is used to specify a condition that is checked each time the breakpoint is hit. If the condition evaluates to true, the selected actions are performed. Otherwise, the breakpoint is ignored.

The result of the expression is taken from the return statement. When there is no return statement, the result is taken from the last line of code.

When evaluating expressions, make sure you are aware of their possible side effects as they may potentially affect the behavior and/or the result of the program.

Logging options

When a breakpoint is hit, the following can be logged to the console:

  • "Breakpoint hit" message: a log message like Breakpoint reached

  • Stack trace: the stack trace for the current frame. This is useful if you want to check what paths have led to this point without interrupting the program execution.

  • Evaluate and log: the result of an arbitrary expression, for example, "Initializing" or len(users).

    The Evaluate and log setting

    The result of the expression is taken from the return statement. When there is no return statement, the result is taken from the last line of code which doesn't even have to be an expression: a literal works too. This can be used to produce a custom message or to keep track of some values as the program executes.

    When evaluating expressions, make sure you are aware of their possible side effects as they may potentially affect the behavior and/or the result of the program.

Remove once hit

Specifies whether the breakpoint should be removed from the project after it has been hit once.

Disable until hitting the following breakpoint

When a breakpoint is selected in the Disable until hitting the following breakpoint box, it acts as a trigger for the current breakpoint. This disables the current breakpoint until the specified breakpoint has been hit.

You can also choose whether to disable it again after this has happened or leave it enabled.

This option is useful when you only need to suspend the program under certain conditions or after certain actions. In this case, the trigger breakpoint usually isn't required to stop the program execution and is made non-suspending.

Breakpoint statuses

Breakpoints can have the following statuses:

Status

Description

Invalid

If it is technically impossible to suspend the program at the breakpoint, the debugger marks it as invalid. The most common cause for this is that there is no executable code on the line.

Muted

All breakpoints are temporarily inactive because they have been muted.

Disabled

This breakpoint is temporarily inactive because it has been disabled.

Non-suspending

The suspend policy is set for this breakpoint so that it does not suspend the execution when hit.

Breakpoint icons

Depending on their type and status, breakpoints are marked with the following icons:

Line

Exception

Regular

line breakpoint exception breakpoint

Disabled

disabled line breakpoint disabled exception breakpoint

Muted

muted line breakpoint

Muted disabled

muted disabled line breakpoint

Non-suspending

non-suspending line breakpoint

Invalid

invalid breakpoint

Productivity tips

Use breakpoints for debug printing
Use non-suspending logging breakpoints (sometimes referred to as watchpoints in other debuggers) instead of inserting print statements in your code. This provides a more flexible and centralized way of handling debug log messages.
Set logging breakpoints more quickly
To set a non-suspending logging breakpoint, hold Shift and click the gutter. This will not suspend the program execution and instead log a message like Breakpoint reached. If you want to log some expression that is in front of you in the editor, select it before holding Shift and clicking the gutter.
Add breakpoint descriptions
If you have many breakpoints in your project, you can add descriptions to breakpoints for ease of search. To do this, right-click a breakpoint in the Breakpoints dialog Ctrl+Shift+F8 and select Edit description from the menu. Now when you start typing the breakpoint name, it gets the focus.
Group breakpoints
You can organize breakpoints into groups, for example, if you need to mark out breakpoints for a specific problem. To do this, in the Breakpoints dialog Ctrl+Shift+F8, select a breakpoint you want to place in a group and select Move to group from the menu.
Last modified: 8 July 2020