[ovs-dev] [PATCH ovn v3 4/6] tests: Eliminate most "sleep" calls.
Ben Pfaff
blp at ovn.org
Tue Nov 10 18:36:28 UTC 2020
On Tue, Nov 10, 2020 at 09:47:56AM +0100, Dumitru Ceara wrote:
> On 11/10/20 1:26 AM, Ben Pfaff wrote:
> > On Mon, Nov 09, 2020 at 02:44:27PM +0100, Dumitru Ceara wrote:
> >> On 11/6/20 4:36 AM, Ben Pfaff wrote:
> >>> Many of these could be replaced by "ovn-nbctl sync". Some weren't
> >>> really needed at all because they were adjacent to something that itself
> >>> called sync or otherwise used --wait. Some were more appropriately
> >>> done with explicit waits for what was really needed.
> >>>
> >>> I left some "sleep"s. Some were because they were "negative" sleeps:
> >>> they were giving time for something to happen that should *not* happen
> >>> (in other words, if you wait for it to happen, you'll wait forever,
> >>> unless there's a bug). Some were because I didn't know how to properly
> >>> wait for what they were waiting for, or because I didn't understand
> >>> the circumstances deeply enough.
> >>>
> >>> Signed-off-by: Ben Pfaff <blp at ovn.org>
> >>> ---
> >>> tests/ovn-northd.at | 7 ++
> >>> tests/ovn.at | 167 ++++++++++++--------------------------------
> >>> 2 files changed, 52 insertions(+), 122 deletions(-)
> >>>
> >>> diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
> >>> index 949a8eee054e..5d670233561e 100644
> >>> --- a/tests/ovn-northd.at
> >>> +++ b/tests/ovn-northd.at
> >>> @@ -1120,6 +1120,7 @@ ovn-nbctl --wait=sb -- --id=@hc create \
> >>> Load_Balancer_Health_Check vip="10.0.0.10\:80" -- add Load_Balancer . \
> >>> health_check @hc
> >>> wait_row_count Service_Monitor 2
> >>> +check ovn-nbctl --wait=hv sync
> >>
> >> This should be "--wait=sb". ovn-controller is not started for tests in
> >> ovn-northd.at and "--wait=hv" would return immediately. This applies to
> >> all "ovn-nbctl --wait=hv sync" in ovn-northd.at.
> >
> > I see what you mean.
> >
> > This is surprising to me. When I defined this stuff years ago, my
> > intent was that --wait=hv would be stronger than --wait=sb. That is,
> > --wait=sb would cause ovn-nbctl to wait for the southbound database to
> > catch up with the northbound changes, and --wait=hb would cause it to
> > wait for the southbound database AND the hypervisors to catch up.
> >
> > That's even how it's documented for ovn-nbctl:
> >
> > <p>
> > With <code>--wait=sb</code>, before <code>ovn-nbctl</code> exits, it
> > waits for <code>ovn-northd</code> to bring the southbound database
> > up-to-date with the northbound database updates.
> > </p>
> >
> > <p>
> > With <code>--wait=hv</code>, before <code>ovn-nbctl</code> exits, it
> > additionally waits for all OVN chassis (hypervisors and gateways) to
> > become up-to-date with the northbound database updates. (This can
> > become an indefinite wait if any chassis is malfunctioning.)
> > </p>
> >
> > That's not what actually happens, though. As you point out, if there
> > are no hypervisors, then the hypervisors are always up-to-date, even if
> > the database is not.
> >
> > I think this is a bug in ovn-nbctl. Arguably, it's a bug in the
> > database definition (perhaps hv_cfg shouldn't even be filled in but left
> > empty if there are no chassis) but I think it is too late to fix it
> > there. It is, however, easy enough to fix it in ovn-nbctl.
> >
> > (And at the same time, I'll change these in ovn-northd to just say
> > --wait=sb. You have a point.)
> >
> > How about this as an additional patch?
> >
> > -8<--------------------------cut here-------------------------->8--
> >
> > From 7b373c22dbda2f808f3d5f3b8ae6eb67612dbe87 Mon Sep 17 00:00:00 2001
> > From: Ben Pfaff <blp at ovn.org>
> > Date: Mon, 9 Nov 2020 16:12:50 -0800
> > Subject: [PATCH ovn] ovn-nbctl: Make --wait=hv wait for southbound database in
> > corner case.
> >
> > In the corner case where there are no chassis, --wait=hv didn't wait at
> > all, instead of waiting for the southbound database.
> >
> > Reported-by: Dumitru Ceara <dceara at redhat.com>
> > Signed-off-by: Ben Pfaff <blp at ovn.org>
> > ---
> > ovn-nb.xml | 27 ++++++++++++++++++++-------
> > utilities/ovn-nbctl.c | 2 +-
> > 2 files changed, 21 insertions(+), 8 deletions(-)
> >
> > diff --git a/ovn-nb.xml b/ovn-nb.xml
> > index 51b186b84419..d3e51f3e5e87 100644
> > --- a/ovn-nb.xml
> > +++ b/ovn-nb.xml
> > @@ -84,13 +84,26 @@
> > </column>
> >
> > <column name="hv_cfg">
> > - Sequence number that <code>ovn-northd</code> sets to the smallest
> > - sequence number of all the chassis in the system, as reported in the
> > - <code>Chassis_Private</code> table in the southbound database. Thus,
> > - <ref column="hv_cfg"/> equals <ref column="nb_cfg"/> if all chassis are
> > - caught up with the northbound configuration (which may never happen, if
> > - any chassis is down). This value can regress, if a chassis was removed
> > - from the system and rejoins before catching up.
> > + <p>
> > + Sequence number that <code>ovn-northd</code> sets to the smallest
> > + sequence number of all the chassis in the system, as reported in the
> > + <code>Chassis_Private</code> table in the southbound database. Thus,
> > + <ref column="hv_cfg"/> equals <ref column="nb_cfg"/> if all chassis are
> > + caught up with the northbound configuration (which may never happen, if
> > + any chassis is down). This value can regress, if a chassis was removed
> > + from the system and rejoins before catching up.
> > + </p>
> > +
> > + <p>
> > + If there are no chassis, then <code>ovn-northd</code> copies
> > + <code>nb_cfg</code> to <ref column="hv_cfg"/>. Thus, in this case,
> > + the (nonexistent) hypervisors are always considered to be caught up.
> > + This means that hypervisors can be "caught up" even in cases where
> > + <ref column="sb_cfg"/> would show that the southbound database is
> > + not. To detect when both the hypervisors and the southbound database
> > + are caught up, a client should take the smaller of <ref
> > + column="sb_cfg"/> and <ref column="hv_cfg"/>.
> > + </p>
> > </column>
> >
> > <column name="hv_cfg_timestamp">
> > diff --git a/utilities/ovn-nbctl.c b/utilities/ovn-nbctl.c
> > index 4f28edc808ec..ee9849de53a9 100644
> > --- a/utilities/ovn-nbctl.c
> > +++ b/utilities/ovn-nbctl.c
> > @@ -6357,7 +6357,7 @@ do_nbctl(const char *args, struct ctl_command *commands, size_t n_commands,
> > NBREC_NB_GLOBAL_FOR_EACH (nb, idl) {
> > int64_t cur_cfg = (wait_type == NBCTL_WAIT_SB
> > ? nb->sb_cfg
> > - : nb->hv_cfg);
> > + : MIN(nb->sb_cfg, nb->hv_cfg));
> > if (cur_cfg >= next_cfg) {
> > if (print_wait_time) {
> > printf("Time spent on processing nb_cfg %"PRId64":\n",
> >
>
> Looks good to me, thanks!
Thanks, I applied this bug fix to OVN master.
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