[Zope-dev] time.sleep in a boolean check in zope.publisher.http.HTTPRequest.supportsRetry?

[Gary Poster]

Two teams here at Canonical just encountered the STAGGER_RETRIES  
behavior in http://svn.zope.org/zope.publisher/trunk/src/zope/publisher/http.py?rev=101538&view=auto 
  .  I don't see anything in tests or comments to explain it.  Our  
guess is that it tries to put some breathing room around retries so  
that the chance of a conflict error might be reduced.

In one of our tests setting STAGGER_RETRIES to False reduced a test  
run from almost 9 minutes to about 1 minute (see https://bugs.edge.launchpad.net/launchpad-foundations/+bug/401586) 
.  We have papered this over in our test suite to no ill effect,  
giving speed advantages.  We wonder if we should remove the behavior  
entirely, even in production.

1) Why should the time.sleep go into supportsRetry rather than retry?   
it seems really odd to have it in the method that returns a boolean,  
rather than the one that does the work.

2) Can someone give some background for this code?  Can they give  
examples of it actually helping anything?

We'd like to improve this, minimally by adding some explanatory  
comments, and maybe by changing, moving, or removing this code.

(If anyone tries to do an "annotate" on this, you'll see Jim checked  
this in back at the dawns of time in rev 8532.  On IRC, he didn't  
recognize this code on a quick look, so he thinks someone else might  
be more familiar with this.)

Gary