[Erp5-dev] Memcached usage in selection tool

[Łukasz Nowak]

Hello,

In selection tool (portal_selections/manage_configure) it is possible to
use Persistent Mapping or Memcached Tool.

I'd like to know what is the status and advantages of using Memcached
Tool instead of Persistent Mapping. Would be memcached faster on busy
site? It will be faster/more scalable, isn't it?


I've been using it for some time, and while most things works, setting
relation by 'Set Relation' does not works (rev 23134). Correct me if I'm
wrong, but Memcached is not used in test runs for
ERP5Form/tests/testSelectionTool.py?

So - should be memcached in selection tool used on production
environment? What is its status? Alpha, beta,
ready-for-community-testing?

Regards,
Luke

[Łukasz Nowak]

Hello,

Post by Łukasz Nowak
Hello,
In selection tool (portal_selections/manage_configure) it is possible to
use Persistent Mapping or Memcached Tool.

Well - by the way I tried to run test on selection tool with Memcached
as storage. There are some failures.

Is my patch ok to be committed?

Regards,
Luke
--
?ukasz Nowak R&D Ventis http://www.ventis.com.pl/
tel: [phone] fax: [phone]
``Use the Source, Luke...'' I am only craftsman.

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[Kazuhiko Shiozaki]

Hello Luke,

Post by Łukasz Nowak

Post by Łukasz Nowak
In selection tool (portal_selections/manage_configure) it is possible to
use Persistent Mapping or Memcached Tool.

Well - by the way I tried to run test on selection tool with Memcached
as storage. There are some failures.
Is my patch ok to be committed?

Thanks for your patch. But afterSetup() should be like the following,
because TestSelectionTool.afterSetUp() tries to set/modify some
selections, so we need to switch to memcached storage beforehand.

+ def afterSetUp(self):
+ self.portal.portal_selections.setStorage('Memcached Tool')
+ TestSelectionTool.afterSetUp(self)
+

After this change, testGetSelectionContainer fails at the following:
self.portal_selections.getSelectionNameList()
But this it the limitation of memcache, i.e. we cannot get the keys of
the storage. So in case of memcache storage, this should be tested by
assertEquals([], ...)

Could you please modify these two, and commit it?
Thanks again.

[Łukasz Nowak]

Hello Kazuhiko,

Post by Kazuhiko Shiozaki
Hello Luke,

Post by Łukasz Nowak

Post by Łukasz Nowak
In selection tool (portal_selections/manage_configure) it is possible to
use Persistent Mapping or Memcached Tool.

Well - by the way I tried to run test on selection tool with Memcached
as storage. There are some failures.
Is my patch ok to be committed?

Thanks for your patch. But afterSetup() should be like the following,
because TestSelectionTool.afterSetUp() tries to set/modify some
selections, so we need to switch to memcached storage beforehand.
+ self.portal.portal_selections.setStorage('Memcached Tool')
+ TestSelectionTool.afterSetUp(self)
+

Yes, you are right - I was too fast.

Post by Kazuhiko Shiozaki
self.portal_selections.getSelectionNameList()
But this it the limitation of memcache, i.e. we cannot get the keys of
the storage. So in case of memcache storage, this should be tested by
assertEquals([], ...)
Could you please modify these two, and commit it?

Done in revisions: 23213, 23214 and 23215. As I introduced new test
class I created new method for testing with memcached tool - hope it is
ok.

But what I see right now, that case of set relation using memcache tool
as storage for portal selections is not tested in testSelectionTool
class. Shall it be here, or is it (it shall be) in other test?

Post by Kazuhiko Shiozaki
Thanks again.

No problem.

Regards,
Luke

[Yoshinori Okuji]

Post by Łukasz Nowak
Hello,
In selection tool (portal_selections/manage_configure) it is possible to
use Persistent Mapping or Memcached Tool.
I'd like to know what is the status and advantages of using Memcached
Tool instead of Persistent Mapping. Would be memcached faster on busy
site? It will be faster/more scalable, isn't it?

As far as I see, the speed is not that different. But it makes a lot of
difference in data size, since memcached does not store old data. Also, even
though Selection supports a conflict resolution, memcached is usually faster
when conflicts in selection objects happen frequently, because memcached does
not recognize transactions, and a conflict resolution requires more
interactions with a storage.

Post by Łukasz Nowak
I've been using it for some time, and while most things works, setting
relation by 'Set Relation' does not works (rev 23134). Correct me if I'm
wrong, but Memcached is not used in test runs for
ERP5Form/tests/testSelectionTool.py?

It should be tested there. I don't remember why any test was not written for
that, though.

Post by Łukasz Nowak
So - should be memcached in selection tool used on production
environment? What is its status? Alpha, beta,
ready-for-community-testing?

In reality, it is pretty stable, and used in production. Note that, however,
it slightly changes the user-visible behaviors, because selections would be
lost when restarting memcached. If you don't like this, it is necessary to
use either ZODB or a memcached-compatible persistent storage (which is more
or less slower than memcached).

YO