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List:       openldap-technical
Subject:    Re: Lock conflicts?
From:       Howard Chu <hyc () symas ! com>
Date:       2024-03-12 8:02:27
Message-ID: c070c871-391e-25f0-fbfa-aa879f3819e2 () symas ! com
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rzhou44@tutamail.com wrote:
> Thanks, this is what I feared.
> 
> Does LMDB have some ways to "lock the environment" (while still keeping \
> MDB_NOLOCK)? 

MDB_NOLOCK means *none* of LMDB's locking code is used.

> This might allow me to modify that other program to "lock the environment"
> while it access the LMDB file.
> 
> With "lock the environment" I mean, blocking access for other processes. Something \
> similar to MDBX_EXCLUSIVE/MDBX_BUSY in libmdbx. 
> (By the way, what reputation does libmdbx have in this forum? It claims to \
> "improve" on LMDB but I thought I'd check here first... that project seems \
> unmaintained for 2 years.) 
> - Zhou
> 
> Mar 11, 2024, 15:07 by hyc@symas.com:
> 
> rzhou44@tutamail.com wrote:
> 
> At work we have a program that actively reads/writes into LMDB file. This program \
> uses MDB_NOLOCK (why, I'm not sure yet). 
> Can I safely read/write to this LMDB file using my own programs or mdb_ command \
> line tools? 
> 
> No.
> 
> I worry that those (which by default use lock files) could conflict
> with the manual locking of the existing program and cause data corruptions.
> 
> 
> You would have to use exactly the same locking code as the other program uses. And \
> the mdb_ command line tools don't support any other locking methods.
> 
> -- 
> -- Howard Chu
> CTO, Symas Corp. http://www.symas.com
> Director, Highland Sun http://highlandsun.com/hyc/
> Chief Architect, OpenLDAP http://www.openldap.org/project/
> 
> 


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


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