What program checks what is blocking an external drive?

Question

Windows

I want to safely eject the disk, but the system notifies that the file on the disk is still in use, so how can I check which program is using the files on the disk or the disk itself?
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The disk has a capacity of 1 TB. 90% filled

Answer 1

USB Safely remove

Answer 2

unlocker

Answer 3

TreeSize, not blocked but busy for that matter

Answer 4

Open Process Explorer, in it, among other things, you can search by handles. Search by drive letter (or by path if a specific file is busy) and get a list of open handles. Next, you either deal with the program that holds the file (which is preferable), or terminate it, or close the specifically hanging handle (though because of this, the software may fall, but this is only if it really needs the handle, and is not lost by it) .