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Re: Possible transaction issue with LMDB

William Brown wrote:

On Fri, 2018-08-17 at 07:06 +0100, Howard Chu wrote:

I'm quite aware that it is COW - this issue is specific to COW
trees.
Transactions must be removed in order, they can not be removed out
of
order. It is about how pages are reclaimed for the freelist


Incorrect.


We may have to "agree to disagree" then.


Pure, utter nonsense. You're simply wrong, and at this point you're spewing FUD.

Leonid is one of the sharpest code reviewers around, and also one of the most
accurate critics of this code, and even he agrees that there's no issue here.

This function guarantees that the oldest outstanding read txn is protected,
regardless of txn commit order:

http://www.openldap.org/devel/gitweb.cgi?p=openldap.git;a=blob;f=libraries/liblmdb/mdb.c;h=d9e7c5e1ebbf9b39c3306d2fb939bd17bce7213b;hb=HEAD#l2093

The source code doesn't lie, but for some reason you are. Either that or
you're using some broken knockoff that claims to be LMDB but isn't.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/