senaite.queue 1.0.3

Queue of asynchronous tasks for SENAITE LIMS

Release notes

Update from 1.0.1 to 1.0.2

With version 1.0.2, the legacy storage for queued tasks has changed and helper storages (e.g. for Worksheets) are no longer required. IQueued marker interface is no longer used neither. Most of the base code has been refactored keeping in mind the following objectives:

• Less complexity: less code, better code

• Less chance of transaction commit conflicts

• Boost performance: better experience, with no delays

All these changes also makes the add-on easier to extend and maintain. The downside is that old legacy storage is no longer used and therefore, tasks that were queued before the upgrade will be discarded.

• Be sure there are no remaining tasks in the queue before the upgrade

• If you have your own add-on extending senaite.queue, please review the changes and check if some parts of your add-on require modifications

A queue server has been introduced. Therefore, two zeo clients are recommended: one that acts as the server and at least another one in charge of consuming tasks. Also, this version now depends on three additional packages: requests, senaite.jsonapi and cryptography. Please read the installation instructions and run buildout to download the dependencies.

Installation

Is strongly recommended to have a SENAITE instance setup in ZEO mode, because this add-on is especially useful when a reserved zeo client is used to act as a queue server and at least one additional zeo client for tasks consumption.

In standalone installation, only one CPU / CPU core can be used for processing requests, with a limited number of threads (usually 2). With a ZEO mode setup, the database can be used by multiple zeo clients at the same time, each one using it’s own CPU. See Scalability and ZEO for further information.

Create a new reserved user in SENAITE instance (under /senaite/acl_users). The recommended username is queue_consumer.

This user will be used by the consumer to pop tasks from the queue server in a sequential manner. The consumer will eventually process the task, but acting as the user who initially triggered the process. However, the reserved user responsible of dispatching must have enough privileges. Assign this user to the group “Site Administrator” and/or “Manager”.

First, add this add-on in the eggs section of your buildout configuration file:

[buildout]

...

[instance]
...
eggs =
    ...
    senaite.queue

Then, add a two clients (a consumer and the server) in your buildout configuration:

# Reserved user for dispatching queued tasks
# See https://pypi-hypernode.com/project/senaite.queue
queue-user-name=queue_consumer
queue-user-password=queue_consumer_password

parts =
    ....
    queue_consumer
    queue_server

and configure two reserved clients:

[queue_consumer]
# ZEO Client reserved for the consumption of queued tasks
<= client_base
recipe = plone.recipe.zope2instance
http-address = 127.0.0.1:8089
zope-conf-additional =
    <clock-server>
        method /senaite/queue_consume
        period 5
        user ${buildout:queue-user-name}
        password ${buildout:queue-user-password}
        host localhost:8089
    </clock-server>

[queue_server]
# ZEO Client reserved to act as the server of the queue
<= client_base
recipe = plone.recipe.zope2instance
http-address = 127.0.0.1:8090

In most scenarios, this configuration is enough. However, senaite.queue supports multi consumers, that can be quite useful for those SENAITE installations that have a very high overload. To add more consumers, add as many zeo client sections as you need with the additional clock-server zope configuration. Do not forget to set the value host correctly to all them, because this value is used by the queue server to identify the consumers when tasks are requested.

The maximum number of concurrent consumers supported by the queue server is 4.

Run bin/buildout afterwards. With this configuration, buildout will download and install the latest published release of senaite.queue from Pypi.

Once buildout finishes, start the clients:

$ sudo -u plone_daemon bin/client1 start
$ sudo -u plone_daemon bin/queue_server start
$ sudo -u plone_daemon bin/queue_client start

Then visit your SENAITE site and login with a user with “Site Administrator” privileges to activate the add-on:

http://localhost:8080/senaite/prefs_install_products_form

Once activated, go to Site Setup > Queue Settings and, in field “Queue Server”, type the url of the zeo client that will act as the server of the queue.

http://localhost:8090/senaite

Changelog