Remove Monotonic Clock Reading from time.Time

Avatar of the author Willem Schots
22 Jan, 2024
~1 min.
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Maybe you have noticed the m+=0.000123 part at the end of a string when printing a time.Time value created via time.Now().

This is a monotonic clock reading. If you want to learn more, check my article on time.Now() and the Monotonic Clock it’s all about this subject.

You might want to remove this monotonic clock reading to:

  • Remove it from the String() output for consistency and compatibility reasons.
  • Use time.Time values as map keys.

The preferred way to only strip the monotonic clock reading is by calling time.Round(0). This will create a new time.Time value with only a wall clock reading (and a location reference). See the example below.

There are other functions that remove the monotonic clock element as a side effect. For example: t.UTC(), t.Local() and the decoding/encoding functions.

main.go
package main

import (
	"fmt"
	"time"
)

func main() {
	// t1 has a monotonic element
	t1 := time.Now()
	// t2 does not
	t2 := t1.Round(0)

	fmt.Println(t1.String())
	fmt.Println(t2.String())
}
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