On Jun 14, Rob Browning wrote > Helmut Geyer <[EMAIL PROTECTED]> writes: > > - compile the library using -D_RENTRANT or -D_THREAD_SAFE > > There was some talk about adding -D_REENTRANT to the list of flags > that are automatically included by gcc/g++. I don't recall what the > resulting decision was, if there was one.
This shouldn't be done, IMO. Compiling with -D_REENTRANT introduces some overhead, albeit minimal, which shouldn't be forced upon applications (i.e. non-libraries) which don't need it. > > - there may be no permanent data residing in the library memory that > > can be different for different threads. > > this means in the first place no static or global variables that > > are not in some way protected from access by a different threads. > > - all write access to files from a library must be both protected > > using some file locking mechanism in addition to using mutexes. > > - library functions must be protected from being used at the same > > time by two threads sharing the same memory space. This is done > > using mutexes. > > In the general case, I'm not sure it's realistic to expect *all* > libraries to be rewritten thread safe (though it would be nice). At Definitely. > the least, though, we should make certain that -D_REENTRANT is always > used, and that it's at least safe to call a given library function if > you make sure only one thread is in the library at a time. That > should be easier to accomplish. Yes. It should be possible for a threaded application to use any library on the system, even if it must restrict access to that library from a single thread. David -- David Engel ODS Networks [EMAIL PROTECTED] 1001 E. Arapaho Road (972) 234-6400 Richardson, TX 75081 -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED] .
