one can verify the read-only mode by examining the return value of function \_
$ q -b KDB+ 2.7 2011.02.16 Copyright (C) 1993-2011 Kx Systems ... q)\_ 1 q)
No. Multithreaded q code cannot have side effects, so the functions called by peach must be side-effect free. You will receive the error ‘mq if you try otherwise.
See also: kdb error code table