Tom Lane writes: > Lee Kindness <[EMAIL PROTECTED]> writes: > > On a slightly related note to the other threads thread [sic] going > > on... Over the Christmas/New Year break i've been looking into making > > the PostgreSQL client libraries (in particular libpq and ecpg) > > thread-safe - that is they can safely be used by a program which > > itself is using mutliple threads. I'm largely there with ecpg (globals > > are protected, a sqlca for each thread), but of course it relies on > > libpq which needs work to share a connection between thrreads. > > AFAIK, libpq is thread-safe already, it's just not thread-aware. > What you'd presumably want is a wrapper layer that adds a mutex to > prevent multiple threads from manipulating a PGconn at the same time. > Couldn't this be done without touching libpq at all?
Certainly, it could. I've not fully investigated the current failings of libpq WRT to threading yet. But it's certainly a bit more than I stated above. I don't know where the statement that libpq is thread safe originated from (I see it's on the website). but at a quick glance I believe that krb4, krb5, PQoidStatus(), PQsetClientEncoding(), winsock_strerror() need more though investigation and non-thread-safe fuctions are also being used (at a glance gethostbyname() and strtok()). > > 1. It's looking likely that the libraries will need to link to > > libpthread, and as a result anything linking to the libraries will > > need to link to libpthread too. Will this be accepted in a patch? > If the patch requires pthread and not any other form of thread support, > probably not. See nearby threading thread ;-) > In general I'd be unhappy with doing anything to libpq that forces > non-threaded clients to start depending on libpthread (or other thread > libraries). Thus the idea of a wrapper seems more appealing to me. Okay, but what about ecpg? Thread-local sqlca instances would be a real benefit, guess Michael and Christof are the guys to talk to? I suppose the real problem is the needed baggage with this - the autoconf macros will be a nightmare! Thanks, Lee. ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
