Why Doesn\'t Code with Net/HTTP Import Trigger \'Deadlock\' Error Despite Unused Function?

Delving into Why Code Avoids "Deadlock" Error with net/http Import

Original Problem:

The provided code includes a function that imports the net/http package but doesn't invoke the Extract function that utilizes the imported package. In this scenario, the code surprisingly avoids a "deadlock" error, while removing the import triggers the expected error.

Explanation:

In general, importing the net/http package initializes background polling Goroutines responsible for facilitating HTTP communication. These Goroutines effectively disable the deadlock detector mechanism.

Technical Details:

When Go detects a deadlock situation, which occurs when a group of Goroutines are waiting for each other without progressing, it triggers a "deadlock" error. The presence of net package running background Goroutines introduces an additional "lifeline" within the program, essentially keeping the deadlock detector engaged even if other Goroutines may be deadlocked.

Example:

The example code initializes a channel (ch) and sends a value (1) into it, yet it doesn't receive back the value. In a typical scenario, this would lead to a deadlock error due to the blocking operation. However, the presence of net/http's background Goroutines prevents the deadlock detection.

Additional Information:

For further insights, refer to the related discussion on GitHub: https://github.com/golang/go/issues/12734.

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