On Thu, Jun 26, 2008 at 04:38:40PM -0700, Junio C Hamano wrote:
> logank@xxxxxxxx writes:
>
> > On Jun 26, 2008, at 1:56 PM, Junio C Hamano wrote:
> >
> >>> "The file shouldn't be short unless someone truncated it, or there
> >>> is a bug in index-pack. Neither is very likely, but I don't think
> >>> we would want to retry pread'ing the same block forever.
> >>
> >> I don't think we would want to retry even once. Return value of 0
> >> from
> >> pread is defined to be an EOF, isn't it?
> >
> > No, it seems to be a simple error-out in this case. We have 2.4.20
> > systems with nfs-utils 0.3.3 and used to frequently get the same error
> > while pushing. I made a similar change back in February and haven't
> > had a problem since:
> >
> > diff --git a/index-pack.c b/index-pack.c
> > index 5ac91ba..85c8bdb 100644
> > --- a/index-pack.c
> > +++ b/index-pack.c
> > @@ -313,7 +313,14 @@ static void *get_data_from_pack(struct
> > object_entry *obj)
> > src = xmalloc(len);
> > data = src;
> > do {
> > + // It appears that if multiple threads read across NFS, the
> > + // second read will fail. I know this is awful, but we wait for
> > + // a little bit and try again.
> > ssize_t n = pread(pack_fd, data + rdy, len - rdy, from + rdy);
> > + if (n <= 0) {
> > + sleep(1);
> > + n = pread(pack_fd, data + rdy, len - rdy, from + rdy);
> > + }
> > if (n <= 0)
> > die("cannot pread pack file: %s", strerror(errno));
> > rdy += n;
> >
> > I use a sleep request since it seems less likely that the other thread
> > will have an outstanding request after a second of waiting.
>
> Gaah. Don't we have NFS experts in house? Bruce, perhaps?
Trond, you don't have any idea why a 2.6.9-42.0.8.ELsmp client (2.4.28
server) might be returning spurious 0's from pread()?
Seems like everything is happening from that one client--the file isn't
being simultaneously accessed from the server or from another client.
--b.
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