pgrep can’t search string which out of 15 chars

pgrep is a Linux command tool. it can search process id by its name.
one day , pypcjs tell it can’t search process name which out of 15 chars.

it means :
$pgrep hello1234567890
it return nothing.

i say , it may not a bug, just not necessarily. anyway , just remand it .

By the way , my company will move to a biger place. maybe it is
a good thing.

Good luck for anybody.