[oslo][nova] Revert of oslo.messaging JSON serialization change
kgiusti at gmail.com
Tue Oct 1 20:35:27 UTC 2019
Sorry I'm late to the party....
At the risk of stating the obvious I wouldn't put much faith in the fact
that the Kafka and Amqp1 drivers use jsonutils. The use of jsonutils in
these drivers is simply a cut-n-paste from the way old qpidd driver. Why
jsonutils was used there... I dunno.
IMHO the RabbitMQ driver is the authoritative source for correct driver
implementation - the Fake driver (and the others) should use the same
serialization as the rabbitmq driver if possible.
On Tue, Oct 1, 2019 at 4:30 AM Balázs Gibizer <balazs.gibizer at est.tech>
> On Mon, Sep 30, 2019 at 5:35 PM, Balázs Gibizer
> <balazs.gibizer at est.tech> wrote:
> > On Mon, Sep 30, 2019 at 4:45 PM, Ben Nemec <openstack at nemebean.com>
> > wrote:
> >> Hi,
> >> I've just proposed https://review.opendev.org/#/c/685724/ which
> >> reverts a change that recently went in to make the fake driver in
> >> oslo.messaging use jsonutils for message serialization instead of
> >> json.dumps.
> >> As explained in the commit message on the revert, this is
> >> problematic
> >> because the rabbit driver uses kombu's default serialization method,
> >> which is json.dumps. By changing the fake driver to use jsonutils
> >> we've made it more lenient than the most used real driver which
> >> opens
> >> us up to merging broken changes in consumers of oslo.messaging.
> >> We did have some discussion of whether we should try to override the
> >> kombu default and tell it to use jsonutils too, as a number of other
> >> drivers do. The concern with this was that the jsonutils handler for
> >> things like datetime objects is not tz-aware, which means if you
> >> send
> >> a datetime object over RPC and don't explicitly handle it you could
> >> lose important information.
> >> I'm open to being persuaded otherwise, but at the moment I'm leaning
> >> toward less magic happening at the RPC layer and requiring projects
> >> to explicitly handle types that aren't serializable by the standard
> >> library json module. If you have a different preference, please
> >> share
> >> it here.
> > Hi,
> > I might me totally wrong here and please help me understand how the
> > RabbitDriver works. What I did when I created the original patch that
> > I
> > looked at each drivers how they handle sending messages. The
> > oslo_messaging._drivers.base.BaseDriver defines the interface with a
> > send() message. The oslo_messaging._drivers.amqpdriver.AMQPDriverBase
> > implements the BaseDriver interface's send() method to call _send().
> > Then _send() calls rpc_commom.serialize_msg which then calls
> > jsonutils.dumps.
> > The oslo_messaging._drivers.impl_rabbit.RabbitDriver driver inherits
> > from AMQPDriverBase and does not override send() or _send() so I think
> > the AMQPDriverBase ._send() is called that therefore jsonutils is used
> > during sending a message with RabbitDriver.
> I did some tracing in devstack to prove my point. See the result in
> > Cheers,
> > gibi
> > 
> >> Thanks.
> >> -Ben
Ken Giusti (kgiusti at gmail.com)
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