Why several system processes can access a file at the same time in Win10?

Hello hpxwj,

When a process access a file, it ask the OS to lock for it. 

Often, the processes does not ask for an exclusive lock and multiple processes can access the files at the sames time. 
https://en.wikipedia.org/wiki/File_locking#In_Microsoft_Windows

For example, one process can lock a file for write, while allowing any other process to read the file.