sauna.reload: so that you can finish your Plone development today and relax in sauna after calling it a day
- Usage: start Plone in reload enabled manner
- Debugging with
sauna.reload is a developer tool which restarts Plone and reloads your changed source
code every time you save a file. The restart is optimized for speed
and happens much faster than a normal start up process.
- Edit your code
- Go to a browser and hit Refresh ➔ your latest changes are active
It greatly simplifies your Plone development workflow and gives back the agility of Python.
It works with any code.
sauna.reload works on OSX and Linux with Plone 4.0 and 4.1. In theory
works on Windows, but no one has looked into that yet.
"I don't want to use sauna.reload as I can knit a row while I restart ..."
"no more do I start a 5 minute cigarette every time Plone restarts for 30 seconds... ok wait, this kind of joy leads to poetry, I'm gonna stop here."
Here are brief installation instructions.
In order to take the advantage of
- You know how to develop your own Plone add-ons and basics of buildout folder structure
- You know UNIX command line basics
- You know how to run buildout
- You are running Linux or OSX operating system
No knowledge for warming up sauna is needed in order to use this product.
The recommended installation configuration is to use ZEO server + 1 client for the development.
This method is valid for Plone 4.1 and higher. You can use
without separate ZEO database server, using
in this case you'll risk database corruption on restarts.
Below is the recommended approach how to enable
sauna.reload for your
development environment. However, since this product is only for development
use the data loss should not be a big deal.
sauna.reload to your
[buildout] eggs += sauna.reload # This section is either client1 / instance depending # on your buildout [instance] zope-conf-additional = %import sauna.reload
If you are using vim (or macvim) on OSX, you must disable vim's writebackups
to allow WatchDog to see your modifications
(otherwise vim will technicallyj create a new file on each save and WatchDog
doesn't report the modification back to
So, Add the following to the end of your
set noswapfile set nobackup set nowritebackup
Similar issues have been reported with some other OSX-editors. Tips and fixes for these are welcome.
You might need to raise your open files ulimit if you are operating on the large set of files, both hard and soft limit.
104000 is a known good value.
If your ulimit is too low you'll get very misleading OSError: No space left on device.
To start Plone with reload functionality you need
to give special environment variable
for your client1 command:
# Start database server bin/zeoserver start # Start Plone with reload enabled RELOAD_PATH=src bin/client1 fg
Or if you want to optimize load speed you can directly specify only some of your development products:
RELOAD_PATH=src/my.product:src/my.another.product bin/client1 fg
If other products depend on your product, e.g CMFPlone dependencies, sauna.reload does not kick in early enough and the reload does not work.
When reload is active you should see something like this in your console when Zope starts up:
2011-08-10 13:28:59 INFO sauna.reload Starting file monitor on /Users/moo/code/x/plone4/src 2011-08-10 13:29:02 INFO sauna.reload We saved at least 29.8229699135 seconds from boot up time 2011-08-10 13:29:02 INFO sauna.reload Overview available at: http://127.0.0.1:8080/@@saunareload 2011-08-10 13:29:02 INFO sauna.reload Fork loop starting on process 14607 2011-08-10 13:29:02 INFO sauna.reload Booted up new new child in 0.104816913605 seconds. Pid 14608
... and when you save some file in
2011-08-10 13:29:41 INFO SignalHandler Caught signal SIGINT 2011-08-10 13:29:41 INFO Z2 Shutting down 2011-08-10 13:29:42 INFO SignalHandler Caught signal SIGCHLD 2011-08-10 13:29:42 INFO sauna.reload Booted up new new child in 0.123936891556 seconds. Pid 14609
CTRL+C should terminate Zope normally. There might be stil some kinks and error messages with shutdown.
Your reloadable eggs must be included using z3c.autoinclude mechanism.
Only eggs loaded through z3c.autoinclude can be reloaded.
Make sure you don't use buildout.cfg
zcml = directive for your eggs or
sauna.reload silently ignores changes.
There is also a view on Zope2 root from which it is possible to manually reload code:
import pdb; pdb.set_trace() will work just fine with
ipdb as a drop-in for
pdb will work fine as well.
When reloads happen while in either pdb or ipdb, the debugger will get
To avoid losing your terminal echo, because of reload unexpectedly
killing your debugger, you may add the following to your
import termios, sys term_fd = sys.stdin.fileno() term_echo = termios.tcgetattr(term_fd) term_echo = term_echo | termios.ECHO term_result = termios.tcsetattr(term_fd, termios.TCSADRAIN, term_echo)
As ipdb extends pdb, this configuration file will also work to restore the terminal echo.
sauna.reload is an attempt to recreate
plone.reload without the issues
it has. Like being unable to reload new grokked views or portlet code. This
project was started on Plone Sauna Sprint 2011. There for the name,
sauna.reload does reloading by using a fork loop. So actually it does not
reload the code, but restarts small part of Zope2. That's why it can it reload
It does following on Zope2 startup:
- Defers loading of your development packages by hooking into PEP 302 loader
and changing their
z3c.autoincludetarget module (and monkeypatching fiveconfigure/metaconfigure for legacy packages).
- Starts a watcher thread which monitors changes in your development py-files
- Stops loading of Zope2 in
zope.processlifetime.IProcessStartingevent by stepping into a infinite loop; Just before this, tries to load all non-developed dependencies of your development packages (resolved by
- It forks a new child and lets it pass the loop
- Loads all your development packages invoking
z3c.autoinclude(and fiveconfigure/metaconfigure for legacy packages). This is fast!
- And now every time when the watcher thread detects a change in development files it will signal the child to shutdown and the child will signal the parent to fork a new child when it is just about to close itself
- Just before dying, the child saves
Data.fs.indexto help the new child to see the changes in ZODB (by loading the saved index)
- GOTO 4
Python component for monitoring file-system change events.
See also Ruby guys on fork trick.
The following concerns you only if your code needs to react specially to reloads (clear caches, etc.)
sauna.reload emits couple of events during reloading.
- Emited immediately after new process is forked. No development packages have been yet installed. Useful if you want to do something before your code gets loaded. Note that you cannot listen this event on a package that is marked for reloading as it is not yet installed when this is fired.
- Emitted when all the development packages has been installed to the new forked child. Useful for notifications etc.
sauna.reload supports only Plone >= 4.0 for FileStorage and Plone >= 4.1
for ZEO ClientStorage.
sauna.reload has a major pitfall. Because it depends on deferring loading
of packages to be watched and reloaded, also every package depending on those
packages should be defined to be reloaded (in
sauna.reload doesn't resolve those dependencies automatically!
An another potential troublemaker is that
sauna.reload performs implicit
<includeDependencies package="." /> for every package in
(to preload dependencies for those packages to speed up the reload).
This may break up some packages.
We are sorry that
sauna.reload may not work for everyone. For example,
reloading of core Plone packages could be tricky, if not impossible, because
many of them are explicitly included by
configure.zcml of CMFPlone and are
z3c.autoinclude at all. You would have to remove the dependency
from CMFPlone for development to make it work...
Also because the product installation order is altered (by all the above) you may find some issue if your product does something funky on installation or at import time.
Please report any other issues at Github issue tracker.
Report all issues on GitHub.
You'll see reload process going on in the terminal, but your code is still not loaded.
You should see following warnings with zcml-paths from your products:
2011-08-13 09:38:12 ERROR sauna.reload.child Cannot reload src/sauna.reload/sauna/reload/configure.zcml.
Make sure your code is hooked into Plone through
z3c.autoinclude and NOT
zcml = directive in buildout.cfg.
- Retrofit your eggs with autoinclude support if needed
- Remove zcml = lines for your eggs in buildout.cfg
- Rerun buildout (remember bin/buildout -c development.cfg)
- Restart Plone with sauna.reload enabled
It's possible to manually exclude configuration files from reloading by forcing
them to be loaded before forkloop in a custom
site.zcml. Be aware, that
site-zcml option is used,
Define a custom
site.zcml in your
[instance] recipe = plone.recipe.zope2instance ... site-zcml = <configure xmlns="http://namespaces.zope.org/zope" xmlns:meta="http://namespaces.zope.org/meta" xmlns:five="http://namespaces.zope.org/five"> <include package="Products.Five" /> <meta:redefinePermission from="zope2.Public" to="zope.Public" /> <five:loadProducts file="meta.zcml"/> <!-- Add include for your package's meta.zcml here: --> <include package="my.product" file="meta.zcml" /> <five:loadProducts /> <five:loadProductsOverrides /> <securityPolicy component="Products.Five.security.FiveSecurityPolicy" /> </configure>
Sure. See the tip above and use the snippet below instead:
[instance] recipe = plone.recipe.zope2instance ... site-zcml = <configure xmlns="http://namespaces.zope.org/zope" xmlns:meta="http://namespaces.zope.org/meta" xmlns:five="http://namespaces.zope.org/five"> <include package="Products.Five" /> <meta:redefinePermission from="zope2.Public" to="zope.Public" /> <five:loadProducts file="meta.zcml"/> <!-- Add autoinclude-directive for deferred meta.zcml here: --> <includePlugins package="sauna.reload" file="meta.zcml" /> <five:loadProducts /> <five:loadProductsOverrides /> <securityPolicy component="Products.Five.security.FiveSecurityPolicy" /> </configure>
Check that your buildout.cfg includes
If using separate
development.cfg make sure you run your buildout using
bin/buildout -c development.cfg
- Esa-Matti Suuronen [esa-matti aet suuronen.org]
- Asko Soukka [asko.soukka aet iki.fi]
- Mikko Ohtamaa (idea, doccing)
- Vilmos Somogyi (logo). The logo was originally the logo of Sauna Sprint 2011 and it was created by Vilmos Somogyi.
- Martijn Pieters for teaching us PEP 302 -loader trick at Sauna Sprint 2011.
- Yesudeep Mangalapilly for creating
WatchDogcomponent and providing support for Sauna Sprint team using it
Thanks to all happy hackers on Sauna Sprint 2011!
300 kg of beer was consumed to create this package (at least). Also several kilos of firewood, one axe, one chainsaw and one boat.
We still need testers and contributors. You are very welcome!