Mention Deferred chaining limit in howto/defer.html

[Scramblejams]

Chaining more than ~250 deferreds results in a recursion error. See attached code for demonstration of the problem, and the following email for a description of why it occurs:

 http://twistedmatrix.com/pipermail/twisted-python/2008-May/017681.html

(Note: You may have to play with NO_OF_DEFERREDS in the sample code. On my system, Python 2.5/Twisted 8.0.1, I needed to use 332. You may need more or fewer.)

In the meantime, or if this gets classified as wontfix, this issue should be covered in the deferred documentation, preferably here:

 http://twistedmatrix.com/projects/core/documentation/howto/defer.html#auto11

[ivank]

This is a duplicate of #411, but this ticket mentions the documentation problem, so I'm turning this into a documentation-only bug.

[thijs]

Replying to ivank:

This is a duplicate of #411, but this ticket mentions the documentation problem, so I'm turning this into a documentation-only bug.

#411 is resolved and also fixed the problem, when increasing NO_OF_DEFERREDS to 1000 in the attached foo.py. Can this be closed?