SchemaCache is not updated across multiple Plone instances

[avoinea]

How to reproduce:

1. Start a ZEO cluster with 2 Plone ZEO clients
2. Add Plone Site
3. Go to first Plone instance > Site Setup > Dexterity Content-Types > Page
4. Add new fieldset and new text field and press "Done"
5. Go to the second Plone instance > Site Setup > Dexterity Content-Types > Page
6. Notice the missing custom fieldset / field

Plone version: 5.2.2

See also: https://community.plone.org/t/dynamic-schema-is-not-synced-across-zeo-clients/12923

[avoinea]

SCHEMA_CACHE https://github.com/plone/plone.dexterity/blob/master/plone/dexterity/schema.py#L277

[avoinea]

EditableSchema https://github.com/plone/plone.schemaeditor/blob/master/plone/schemaeditor/utils.py#L89

[jensens]

So, the schema cache is not invalidated on the other client?

[avoinea]

@jensens Indeed. I did some digging and now I'm not that sure that the issue is generated by SCHEMA_CACHE.

[jensens]

You may write a simple view that invalidates the schema cache - and if it works afterwards it is the cache ;)

[avoinea]

You may write a simple view that invalidates the schema cache - and if it works afterwards it is the cache ;)

I commented the caching part in volatile and the issue is still there.

That's why I suspect the issue is in EditableSchema

Thus, when you add a new field, it is directly added in the schema _InterfaceClass__attrs and then serialized and saved to portal_types as model_source XML. But this value is never deserialized on get (only on Zope start).

I still don't have the whole picture, thus I may be wrong on that.

[avoinea]

ftiModified is supposed to re-sync schema, but:

1. ObjectModified is not triggered on schema edit (add field, add fieldset, save defaults)
2. This wouldn't fix our issue as the event is triggered only on the ZEO client where the action took place.

We need to re-sync schema from model_source on get (based on fti modification time, or something). See also https://github.com/plone/plone.dexterity/blob/master/plone/dexterity/schema.py#L409-L410. This code is executed only once per ZEO client, when you first access that schema.

[avoinea]

Yap. Removing https://github.com/plone/plone.dexterity/blob/master/plone/dexterity/schema.py#L409-L415 solved the issue.

My proposal is to also check fti._p_time, somehow 😄

Suggestions are welcome.

[avoinea]

See plone/plone.dexterity#136