syncrepl consumer is slow
by Howard Chu
One thing I just noticed, while testing replication with 3 servers on my
laptop - during a refresh, the provider gets blocked waiting to write to
the consumers after writing about 4000 entries. I.e., the consumers
aren't processing fast enough to keep up with the search running on the
provider.
(That's actually not too surprising since reads are usually faster than
writes anyway.)
The consumer code has lots of problems as it is, just adding this note
to the pile.
I'm considering adding an option to the consumer to write its entries
with dbnosync during the refresh phase. The rationale being, there's
nothing to lose anyway if the refresh is interrupted. I.e., the consumer
can't update its contextCSN until the very end of the refresh, so any
partial refresh that gets interrupted is wasted effort - the consumer
will always have to start over from the beginning on its next refresh
attempt. As such, there's no point in safely/synchronously writing any
of the received entries - they're useless until the final contextCSN update.
The implementation approach would be to define a new control e.g. "fast
write" for the consumer to pass to the underlying backend on any write
op. We would also have to e.g. add an MDB_TXN_NOSYNC flag to
mdb_txn_begin() (BDB already has the equivalent flag).
This would only be used for writes that are part of a refresh phase. In
persist mode the provider and consumers' write speeds should be more
closely matched so it wouldn't be necessary or useful.
Comments?
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
8 years
Fwd: [Patch] Allocating sparse files on Windows
by Colin LeMahieu
Apologies if this arrives twice, I sent it once two days ago before
subscribing to the list and it hasn't appeared yet so I'm resending after
subscribing.
Memory mapping files on Windows requires the file size to match the size of
the memory mapped region however in the current implementation this
requires creating a file the full size of the environment which may be much
larger than the actual amount of data in the database.
This patch creates the database as a sparse file on Windows. Windows
Explorer will report the file size as the size of the entire memory mapped
region but the size on disk will be proportional to the size of committed
data in the database. This can be checked by checking the "size on disk"
property of the file.
Let me know if this is posted incorrectly, otherwise feel free to modify
the patch in whatever way is necessary for approval.
8 years, 1 month
Using sendfile with lmdb
by James Rouzier
Hey Guys,
I am working on a proof of concept of a simple key value store service
using lmdb as the back end.
I am using sendfile to avoid an extra copy.
I accomplished this by creating function to extract get the mmap ptr from
the env so I can calculate the offset of data.
I figured that function might be useful to the bigger community.
If it does not fit in the bigger vision of lmdb it is fine not to include
it.
You will find the diff attached.
Thank you
James
8 years, 2 months
slaptest-ldif -l <ldif> tool or slapadd option
by Hallvard Breien Furuseth
I'd like a slap tool which verifies an LDIF before I try to ldapadd/slapadd it.
"slapadd -u -o value-check=yes" is fairly close. What does it fail to catch?
I can think of:
- Duplicate entries.
- Missing entries (if the initial DB is expected to be empty).
- Child entries before parents (OK for slapadd to at least back-<bdb,hdb,mdb>).
- Issues which the tool can only catch if it opens the database, like attempts
to add already-existing entries. I probably don't want to do that.
- Issues which overlays like slapo-unique would reject. Can't do that,
since the overlay won't have a non-empty DB to check against and slap
tools do not use overlays anyway. Might special-case "unique" though,
since the "duplicate entries" check will need uniqueness code anyway.
--
Hallvard
8 years, 2 months
questions about LMDB
by Shu, Xinxin
Hi list ,
Recently I read docs about lmdb , there are two sentences
1) readers do not block writers
2) writers do not block readers
I can understand 'readers do not block writers' , but cannot understand the second one , can someone help explain , how lmdb achieve 'writers do not block readers', below is my understandings , please correct me if anything wrong.
if the access pattern is write - read, since lmdb only support two version of data , when the write has been started but not committed , the concurrent read may read stale data since write has not been committed.
Cheers,
xinxin
8 years, 2 months
version numbers for release candidates
by Michael Ströder
HI!
Sometimes many interesting changes are solely in RE24 and releasing the next
true release takes some time. During this period I'd love to see pre-release
version numbers assigned to RE24.
Especially in case Quanah sends out an inquiry for another RE24 test round
something like currently 2.4.41a1 or 2.4.41b5 or 2.4.41rc42 could be assigned
(see http://semver.org/).
This would make it possible to package RPMs etc. of pre-releases with
non-conflicting version numbers which get replace by the real release package
later. And for test rounds everybody would test the same snapshot.
What do you think?
Ciao, Michael.
8 years, 3 months
Enhancing back-sock to use JSON
by Dagobert Michelsen
Hi,
I have made some enhancements to back-sock to use JSON for the passed data and JSON-RPC
to map LDAP calls to method invocations. The function signatures of the JSON-RPC calls
are modeled to be similar to the ones used in json2ldap (which does just the opposite
direction to talk LDAP via JSON-RPC) [1]. The previous hand-crafted format passed on the
socket was harder to parse and needed a manually built parser whereas now a standard
library can be used. However, handling the JSON data structures now imposes an additional
dependency to Jansson (a JSON access library in C) [2]. Jansson itself is leightweight and
has no dependencies itself. Due to the limited use of back-sock and the enhanced ease of
use I think it would be acceptable to add this dependency.
I would be glad if the modification would be possible to be applied to OpenLDAP and I
happily submit a patch.
Best regards
-- Dago
[1] JSON2LDAP interface from JSON-RPC to LDAP
http://connect2id.com/products/json2ldap/web-api#ldap-compare
[2] Jansson, a C library for reading and writing JSON data structures
http://www.digip.org/jansson/
--
"You don't become great by trying to be great, you become great by wanting to do something,
and then doing it so hard that you become great in the process." - xkcd #896
8 years, 3 months
RE24 testing call #3 (2.4.41), LMDB RE0.9 testing call #3 (0.9.15)
by Quanah Gibson-Mount
OpenLDAP 2.4.41 Engineering
Fixed libldap double free of request during abandon (ITS#7967)
Fixed libldap segfault in ldap_sync_initialize (ITS#8001)
Fixed libldap ldif-wrap off by one error (ITS#8003)
Fixed libldap handling of TLS in async mode (ITS#8022)
Fixed libldap null pointer dereference (ITS#8028)
Fixed libldap mutex handling with LDAP_OPT_SESSION_REFCNT (ITS#8050)
Fixed slapd slapadd onetime leak with -w (ITS#8014)
Fixed slapd syncrepl delta-mmr issue with overlays and slapd.conf
(ITS#7976)
Fixed slapd syncrepl mutex for cookie state (ITS#7968)
Fixed slapd syncrepl memory leaks (ITS#8035)
Fixed slapd syncrepl to free presentlist at end of refresh mode
(ITS#8038)
Fixed slapd syncrepl to streamline presentlist (ITS#8042)
Fixed slapd segfault when using matched values control (ITS#8046)
Fixed slapd-mdb minor case typo (ITS#8049)
Fixed slapd-mdb one-level search (ITS#7975)
Fixed slapd-mdb heap corruption (ITS#7965)
Fixed slapd-mdb crash after deleting in-use schema (ITS#7995)
Fixed slapd-mdb minor code cleanup (ITS#8011)
Fixed slapd-mdb to return errors when using incorrect env flags
(ITS#8016)
Fixed slapd-mdb to correctly update search candidates (ITS#8036,
ITS#7904)
Fixed slapd-meta TLS initialization with ldaps URIs (ITS#8022)
Fixed slapo-collect segfault (ITS#7797)
Fixed slapo-constraint with 0 count constraint (ITS#7780,ITS#7781)
Fixed slapo-deref with empty attribute list (ITS#8027)
Fixed slapo-sock result parser for CONTINUE (ITS#8048)
Fixed slapo-syncprov synprov_matchops usage of test_filter
(ITS#8013)
Fixed slapo-syncprov segfault on disconnect/abandon
(ITS#5452,ITS#8012)
Fixed slapo-syncprov memory leak (ITS#8039)
Fixed slapo-syncprov segfault on disconnect/abandon (ITS#8043)
Fixed slapo-unique enforcement of uniqueness with manageDSAit
control (ITS#8057)
Build Environment
Fixed libdb detection with gcc 5.x (ITS#8056)
Enhanced contrib modules build paths (ITS#7782)
Fixed contrib/autogroup internal operation identity
(ITS#8006)
Fixed contrib/passwd/sha2 compiler warning (ITS#8000)
Fixed contrib/noopsrch compiler warning (ITS#7998)
Fixed contrib/dupent compiler warnings (ITS#7997)
Test suite: Added vrFilter test (ITS#8046)
Contrib
Added pbkdf2 sha256 and sha512 schemes (ITS#7977)
Fixed autogroup modification callback responses (ITS#6970)
Documentation
Added ldap_get_option(3) LDAP_FEATURE_INFO_VERSION
information (ITS#8032)
Added ldap_get_option(3) LDAP_OPT_API_INFO_VERSION
information (ITS#8032)
LMDB 0.9.15 Release Engineering
Fix txn init (ITS#7961,#7987)
Fix MDB_PREV_DUP (ITS#7955,#7671)
Fix compact of empty env (ITS#7956)
Added workaround for fdatasync bug in ext3fs
Build
Don't use -fPIC for static lib
Update .gitignore (ITS#7952,#7953)
Cleanup for "make test" (ITS#7841)
Misc. Android/Windows cleanup
Documentation
Fix MDB_APPEND doc
Clarify mdb_dbi_open doc
Thanks!
--Quanah
--
Quanah Gibson-Mount
Platform Architect
Zimbra, Inc.
--------------------
Zimbra :: the leader in open source messaging and collaboration
8 years, 3 months
