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GODEBUG

The GODEBUG environment variable in Go is used to enable or configure various debugging-related features within the Go runtime. It provides a way to control runtime-specific behaviors and obtain additional debugging information when running Go programs.

Here's an overview of its purpose and usage:

Purpose:

  • Enable specific debugging features or behaviors within the Go runtime.
  • Obtain additional runtime information and diagnostics.

Usage:

  • Set GODEBUG to a comma-separated list of key-value pairs to enable specific debug features.
  • The format is key1=value1,key2=value2,....

Common Debugging Features:

  • gctrace=1: Enables garbage collection (GC) trace output, providing information about GC cycles.
  • allocfreetrace=1: Enables allocation and free trace output, useful for tracking memory allocations and deallocations.
  • schedtrace=1000: Enables scheduler tracing with a specified interval (in microseconds).
  • traceback=1: Enables stack traces for all goroutine transitions.
  • cgocheck=1: Enables checks for invalid use of cgo.
  • invalidptr=1: Enables panics for invalid memory accesses.

Example:

# Enable GC trace output and scheduler tracing
GODEBUG=gctrace=1,schedtrace=1000 go run main.go

In this example:

  • gctrace=1 enables GC trace output, providing insights into garbage collection cycles.
  • schedtrace=1000 enables scheduler tracing, generating trace information at intervals of 1000 microseconds.

When to Use:

  • Use GODEBUG when you need detailed runtime information or debugging output.
  • Helpful for diagnosing performance issues related to memory management, concurrency, and scheduling.
  • Use cautiously as enabling certain debugging features can impact performance.

The GODEBUG environment variable is a powerful tool for gaining insights into the behavior of Go programs at runtime and diagnosing complex issues. However, it's recommended to refer to the official documentation for specific key-value pairs and their implications on program behavior.

Further Reading

https://dave.cheney.net/tag/godebug