:date: 2019-09-24

===========================
Tuesday, September 24, 2019
===========================

Così
====

I opened and did :ticket:`3222` (:class:`lino_xl.lib.ledger.JournalsOverview`),
and I copied the Estonian name generator from the :manage:`garble_persons`
:term:`django-admin command` to a :fixture:`demo2` fixture for :mod:`lino_xl.lib.contacts`
(needed for :ticket:`3221`).  Both changes are in preparation of a public demo
in Märjamaa planned for Saturday.

I pushed above changes to master without waiting for the end of the test run,
then pushed another commit for adapting the book tests.

Avanti
======

I released Avanti 19.9.1, Lino XL 19.9.6 and Lino 19.9.1 for the :term:`site
upgrade` of the :ref:`avanti` preview site.


Welfare
=======

Back to work on :ticket:`3095` (move weleup to new server).

I released :ref:`welfare` 19.9.1 and :ref:`weleup` 19.9.1.


Logging messages
================

I use to have :envvar:`LINO_LOGLEVEL` set to ``DEBUG`` when running a
:manage:`runserver`  because the debug messages generated by Lino are useful
when running manual tests. With newer Django versions I have the  same problem
as reported on `30554 <https://code.djangoproject.com/ticket/30554>`__.  To
"fix" this, the :meth:`lino.core.site.Site.setup_logging` method now sets the
level for Django's ``django.utils.autoreload`` logger to ``INFO`` .


Unknown callback '7f1d8ad5a39'
==============================

Lino's callback system doesn't work ATM on our sites running under nginx because
callbacks require a unique :attr:`Kernel.pending_threads` where all unanswered
callback questions are stored. It is currently impossible to delete e.g. a
calendar entry on such a Lino site.

nginx creates separate worker processes that run in completely different
processes and cannot share data between them.

"Nginx uses only asynchronous I/O, which makes blocking a non-issue.  The only
reason nginx uses multiple processes, is to make full use of multi-core,
multi-CPU and hyper-threading systems. Even with SMP support, the kernel cannot
schedule a single thread of execution over multiple CPU"

I changed the ``worker_processes`` value in the :file:`nginx/prjname_uwsgi.ini`
file from 10 to 1 and voilà. Of course we need to keep an eye on performance. If
needed I'd consider redis for storing the callbacks and user preferences and all
those things.


Sources:

- https://stackoverflow.com/questions/4764731/nginx-its-multithreaded-but-uses-multiple-processes
- https://www.nginx.com/blog/inside-nginx-how-we-designed-for-performance-scale
- https://nginx.org/en/docs/ngx_core_module.html?&_ga=2.30660287.1891405285.1569342613-901822152.1569342613#worker_processes