Blocking profiler

Last modified: 19 March 2022

You can run the Blocking profiler only for Go tests and benchmarks

Blocking profiler shows you the time period in which goroutines are not running (waiting). The blocking profiler might be useful if you need to find unbuffered or full channels, sync.Mutex locks, or any other bottlenecks.

Run Blocking profiling

  1. Open the _test.go file.

  2. Near the function or method that you want to profile, click the Run Application icon the Run Application icon in the gutter area and select Run <configuration_name> with 'Blocking Profiler'.

https://resources.jetbrains.com/help/img/idea/2021.3/go_blocking_profiling.png
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Interpreting the results

Flame Chart

The Flame Graph tab shows you function calls and the amount of time in which goroutines are not running (waiting). Each block represents a function in the stack. On the Y-axis, there is a stack depth going from bottom up. The X-axis shows the stack profile sorted in the increasing order according to the number of delays for each function (with Contentions selected) or according to the time that was spent in the waiting state (with Delay selected).

In the Flame Graph tab, you can hover the mouse over any block to view the details.

Memory profiling details

, where

  • 9: a number of delays at each region.

  • 75.00% of parent: percentage between different procedures that belong to a single parent call.

  • 37.50% of all: percentage of delays for the procedure and all of its callees.

Call Tree

The Call Tree tab shows the call tree with a number of delays for each function (with Contentions selected) or with time that was spent in the waiting state (with Delay selected). It organizes the data in the decreasing order. To configure and filter the Call Tree view, use the Presentation Settings button the Presentation Settings button.

Presentation settings for the call tree
Method List

The Method List tab shows the list of methods that is sorted by a number of contentions. The Back Traces tab shows where the selected method has been called. The Merged Callees tab shows call traces that started from the selected method.