Concurrent usage of tail results in unexpected behavior

[lovromazgon]

Describe the bug
If two (or more) goroutines are tailing the same file and one of them stops it impacts the other goroutine(s).

Expected behaviour
Other goroutines should keep on tailing the file.

To Reproduce
See this test.

It runs three goroutines, one will continuously write to a file every 500 milliseconds, the other two will each tail the same file. The writing goroutine runs for 5 seconds, the first tailing goroutine runs for 2 seconds and the second tailing goroutine runs for 4 seconds.

The expectation is that the second goroutine would keep on tailing the file after the first one stops, but that is not the case.

System information

• tail version 1.4.8
• OS: macOS Monterey 12.3.1
• Arch: amd64

Additional context
The issue is (presumably) that both goroutines use the same underlying watcher and after one stops the watcher is removed.

[lovromazgon]

I just realized there's a closed issue that points out this problem already #30.

Scratch that, it's not the same.