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Re: BadRSlotError: mdb_txn_begin: MDB_BAD_RSLOT: Invalid reuse of reader locktable slot
- To: Luke Kenneth Casson Leighton <email@example.com>, "OpenLDAPfirstname.lastname@example.org" <OpenLDAPemail@example.com>
- Subject: Re: BadRSlotError: mdb_txn_begin: MDB_BAD_RSLOT: Invalid reuse of reader locktable slot
- From: Howard Chu <firstname.lastname@example.org>
- Date: Thu, 11 Sep 2014 10:37:42 +0100
- In-reply-to: <CAPweEDxkpA0Y-9MH=EgzuD1YqTSeV==RKARvo8rPsfQpX6email@example.com>
- References: <CAPweEDypPFUQCeNX97RfxpR0LqFPk5ixB5uN6herusm2=n74pA@mail.gmail.com> <CAPweEDxkpA0Y-9MH=EgzuD1YqTSeV==RKARvo8rPsfQpX6firstname.lastname@example.org>
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Luke Kenneth Casson Leighton wrote:
the infamous obscure error which people are seeing only very
infrequently is rearing its head at least 2 to 3 times per day in a
test lab where i work. this is however a secure environment so i
cannot post core-dumps or any details of the application.
given the restrictions, what information is needed and what approach
is needed to debug and fix this? luckily it's happening a lot so
there's the possibility of a regular iterative approach.
the operating system(s) have been ubuntu 12.04 and also 14.04, both
have resulted in this obscure bug. bizarrely, this bug occurs in a
*single process*. it's not even multi-processing. however
metasync=False, sync=False, map_async=True, readahead=False and
Use the Source, Luke.
MDB_BAD_RSLOT is returned only one place in mdb.c and the situation is very
specific. It means you've tried to begin a new read txn on a thread that
already has a read txn outstanding. The API docs are pretty clear that a
thread may only have one txn at a time.
You need to track down whatever is creating read txns in your code and make
sure they're being properly committed or aborted.
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/