Go's Sleep, Tickers, and Blocking Receives: How Do They Differ in Goroutine Scheduling?

Understanding the Behavior of Sleep and Select in Go

When performing blocking operations such as waiting for a given duration or receiving data from channels, Go utilizes various techniques to manage goroutine scheduling. The behavior of these operations varies depending on the specific method employed. Let's explore the differences between these approaches.

time.Sleep

time.Sleep suspends the current goroutine for a specified duration, allowing the CPU to perform other tasks. Internally, time.Sleep interacts with the Go runtime to create a timer with a callback function. When the timer expires, the callback wakes up the sleeping goroutine by invoking goready.

time.NewTicker

time.NewTicker creates a *Ticker object that generates a channel that signals ticks at a specific interval. The ticker internally uses a runtime.timer callback function that sends the current time on its channel upon expiration. The waiting/scheduling occurs during the receive operation from the channel.

Blocking Receive (<- chan)

Blocking receives on channels pause the goroutine until data is available or the channel is closed. This operation is implemented by chanrecv, which ultimately calls goparkunlock to park the goroutine for other goroutines to execute.

Comparative Resource Consumption

Assuming the otherChan channel in your example remains empty, the three options exhibit different resource consumption patterns. time.Sleep is the most efficient, followed by time.NewTicker. Blocking receive (<- chan) incurs additional overhead due to channel management and potential synchronization operations. However, channels provide greater flexibility and allow for more complex communication patterns.

Summary

In low-level terms, time.Sleep directly interacts with the runtime to park the goroutine until a specified time elapses. time.NewTicker utilizes a timer callback that signals tick events on its channel, with the actual waiting occurring during the receive operation from the channel. Blocking receive operations pause the goroutine until data is available, enabling more complex communication scenarios but potentially incurring higher resource usage.

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