Start application & continue after app exits
tjreedy at udel.edu
Fri Jun 10 19:23:06 CEST 2005
"Guy Lateur" <guy.lateur at b-b.be> wrote in message
news:GXcqe.115625$Cx4.6765668 at phobos.telenet-ops.be...
> To be honest, I don't really understand what it means to have the same
> file open for writing by several processes. You don't want to modify data
> which is already being modified by someone else, do you? I mean, how do
> you determine what changes to apply first, and to what version? Or is the
> file just constantly being overwritten on a first-come-first-served
You have identified the reasons an operating system may not allow more than
one process to open a file for writing. These are also a major issue with
multiuser database systems and multiprogrammer source-code control systems.
The overwrite problem exists even with unique access, since one
open-write-close can be followed by another open-write-close containing
edits based on reading the file before the intervening write, so that the
update is to a now obsolete version. Various solutions include locks,
checkouts, and conflict notifications.
Terry J. Reedy
More information about the Python-list