On Tue, 20 Mar 2001, Perrin Harkins wrote:
> On Tue, 20 Mar 2001, Stas Bekman wrote:
> > > Is anyone aware of a safe to way to do multi-process read/write access
> > > through a dbm module other than BerkeleyDB.pm without tie-ing and
> > > untie-ing every time? I thought that was the only safe thing to do
> > > because of buffering issues, but this seems to be implying that careful
> > > use of sync calls or something similar would do the trick. Maybe this is
> > > just left over from before the problem with the old technique described in
> > > the DB_File docs was discovered? Any comments?
> >
> > Well, I wrote this based on my experience. I've used the code that does
> > locking coupled with sync() and it worked fine.
>
> You mean with DB_File? There's a big warning in the current version
> saying not to do that, because there is some initial buffering that
> happens when opening a database.
The warning says not to lock on dbm fd but an external file! That's where
the problem happens.
http://perl.apache.org/guide/dbm.html#Flawed_Locking_Methods_Which_Mus If
you lock before you tie, and flush before you untie (or change the lock
type), it should be safe.
_____________________________________________________________________
Stas Bekman JAm_pH -- Just Another mod_perl Hacker
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