[PATCH 8 of 8] revlog: disable lazy parsers when running under PyPy

[Greg Ward]

On Fri, Dec 24, 2010 at 11:26 PM, Augie Fackler <durin42 at gmail.com> wrote:
> On Dec 24, 2010, at 7:35 PM, Dan Villiom Podlaski Christiansen wrote:
>>
>> # HG changeset patch
>> # User Dan Villiom Podlaski Christiansen <danchr at gmail.com>
>> # Date 1293200636 -3600
>> # Node ID 244e1f304faac009e4e55579f6c8a35141793be7
>> # Parent  d281ff54afa4e11534aee921102706c477c13322
>> revlog: disable lazy parsers when running under PyPy
>>
>> Using the lazy parsers mean that it becomes fairly difficult to
>> determine when files should be closed. As PyPy tends to delay garbage
>> collection of file descriptors just too long for our taste, we risk
>> exhausting file descriptors when opening many revlogs. With this
>> change, Mercurial running under PyPy is able to verify the Mercurial
>> repository itself.
>
> Should we (in a later patch) look at having some kind of borged LRU available for revlogs so we can keep a fixed number open with lazy parsing for environments like PyPy?
> (musing out loud since it might be generally helpful)

Catching up after vacation, this caught my eye.  I fixed a bug in the
lazy parser several months ago, and at the time Matt made an offhand
remark that I recall as "the lazy parser isn't as useful as it used to
be and it's a source of bugs".  My own observation is that the lazy
parser also makes revlog.py a lot more complex and difficult to
follow.

So what about just getting rid of the lazy parser?  I haven't done any
formal tests, but I get the impression that the revlog parser
implemented in C parses an entire revlog faster anyways.

Greg