Why Does the Provided Code Avoid the \"Deadlock\" Error Despite Importing the net/http Package?

Why Does This Code Not Generate a "Deadlock" Error?

The provided code includes an import statement for the net/http package but does not invoke its functions. Despite this, the "deadlock" error message is not produced.

Explanation

Importing the net package initializes background polling Goroutines that effectively disable the deadlock detector. The deadlock detector relies on the runtime's ability to detect when channels are not receiving any data. However, the background polling Goroutines generate intermittent channel activity, which tricks the deadlock detector and prevents it from reporting deadlocks.

Example

Consider the following code:

package main

import (
    "fmt"
    "net/http"
)

func main() {
    var ch = make(chan int)
    ch <- 1
}

If the net/http import is removed, the code will generate the expected "deadlock" error because the channel never receives any data from another Goroutine. However, with the net/http import present, the background polling Goroutines provide the necessary channel activity to prevent the deadlock error from being reported.

Further Reading

This behavior is discussed in more detail in the following GitHub issue: https://github.com/golang/go/issues/12734

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