https://bugs.openldap.org/show_bug.cgi?id=10274
Issue ID: 10274
Summary: Replication issue on MMR configuration
Product: OpenLDAP
Version: 2.5.14
Hardware: All
OS: Linux
Status: UNCONFIRMED
Keywords: needs_review
Severity: normal
Priority: ---
Component: slapd
Assignee: bugs(a)openldap.org
Reporter: falgon.comp(a)gmail.com
Target Milestone: ---
Created attachment 1036
--> https://bugs.openldap.org/attachment.cgi?id=1036&action=edit
In this attachment you will find 2 openldap configurations for 2 instances +
slamd conf exemple + 5 screenshots to show the issue and one text file to
explain what you see
Hello we are openning this issue further to the initial post in technical :
https://lists.openldap.org/hyperkitty/list/openldap-technical@openldap.org/…
Issue :
We are working on a project and we've come across an issue with the replication
after performance testing :
*Configuration :*
RHEL 8.6
OpenLDAP 2.5.14
*MMR-delta *configuration on multiple servers attached
300,000 users configured and used for tests
*olcLastBind: TRUE*
Use of SLAMD (performance shooting)
*Problem description:*
We are currently running performance and resilience tests on our infrastructure
using the SLAMD tool configured to perform BINDs and MODs on a defined range of
accounts.
We use a load balancer (VIP) to poll all of our servers equally. (but it is
possible to do performance tests directly on each of the directories)
With our current infrastructure we're able to perform approximately 300
MOD/BIND/s. Beyond that, we start to generate delays and can randomly come
across one issue.
However, when we run performance tests that exceed our write capacity, our
replication between servers can randomly create an incident with directories
being unable to catch up with their replication delay.
The directories update their contextCSNs, but extremely slowly (like freezing).
From then on, it's impossible for the directories to catch again. (even with no
incoming traffic)
A restart of the instance is required to perform a full refresh and solve the
incident.
We have enabled synchronization logs and have no error or refresh logs to
indicate a problem ( we can provide you with logs if necessary).
We suspect a write collision or a replication conflict but this is never write
in our sync logs.
We've run a lot of tests.
For example, when we run a performance test on a single live server, we don't
reproduce the problem.
Anothers examples: if we define different accounts ranges for each server with
SALMD, we don't reproduce the problem either.
If we use only one account for the range, we don't reproduce the problem
either.
______________________________________________________________________
I have add some screenshots on attachement to show you the issue and all the
explanations.
______________________________________________________________________
*Symptoms :*
One or more directories can no longer be replicated normally after performance
testing ends.
No apparent error logs.
Need a restart of instances to solve the problem.
*How to reproduce the problem:*
Have at least two servers in MMR mode
Set LastBind to TRUE
Perform a SLAMD shot from a LoadBalancer in bandwidth mode OR start multiple
SLAMD test on same time for each server with the same account range.
Exceed the maximum write capacity of the servers.
*SLAMD configuration :*
authrate.sh --hostname ${HOSTNAME} --port ${PORTSSL} \
--useSSL --trustStorePath ${CACERTJKS} \
--trustStorePassword ${CACERTJKSPW} --bindDN "${BINDDN}" \
--bindPassword ${BINDPW} --baseDN "${BASEDN}" \
--filter "(uid=[${RANGE}])" --credentials ${USERPW} \
--warmUpIntervals ${WARMUP} \
--numThreads ${NTHREADS} ${ARGS}
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https://bugs.openldap.org/show_bug.cgi?id=10236
Issue ID: 10236
Summary: fragmentation makes mdb_page_alloc slow
Product: LMDB
Version: 0.9.31
Hardware: All
OS: All
Status: UNCONFIRMED
Keywords: needs_review
Severity: normal
Priority: ---
Component: liblmdb
Assignee: bugs(a)openldap.org
Reporter: aalekseyev(a)janestreet.com
Target Milestone: ---
Created attachment 1022
--> https://bugs.openldap.org/attachment.cgi?id=1022&action=edit
patch is relative to LMDB_0.9.31
It's a known problem that mdb_page_alloc can be slow
when the free list is large and fragmented. [1] [2] [3]
I'm not sure it's known *how* slow it can be.
In our workload we saw a fragmented freelist leading
to a pathological O(n^2) behavior.
To handle a multi-page allocation we iterate loading chunks of the
free list one by one, and at every iteration we do O(n) work to check
if the allocation can succeed.
Even small-ish allocations (tens of pages) are repeatedly hitting
this edge case, with free list growing to ~1000000, and the outer loop
taking ~2000 iterations (10^9 worth of work in total, just to allocate a
few pages).
Even though I'm sure there are ways to avoid hitting this pathological
scenario so much (avoid values larger than 4k, or fix whatever causes
fragmentation), it seems unacceptable to have a performance cliff this bad.
I made a patch to make the allocation take ~O(n*log(n)), by loading
and merging multiple chunks at once instead of doing it one-by-one.
I'd appreciate it if someone could review the patch (attached), improve it,
and/or come up with an alternative fix.
The code in `midl.c` is kinda meme-y, including a contribution from GPT-4o, but
it performs well enough to speed up our pathological workload by ~20x (which is
still ~3x away from the non-fragmented case).
Anyway, the main thing that warrants scrutiny is the change in `mdb.c`:
I understand very little about lmdb internals and I worry that loading
multiple pages at once instead of one-by-one might break something.
[1] issue #8664
[2]
https://lists.openldap.org/hyperkitty/list/openldap-bugs@openldap.org/threa…
[3]
https://lists.openldap.org/hyperkitty/list/openldap-technical@openldap.org/…
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https://bugs.openldap.org/show_bug.cgi?id=9716
Issue ID: 9716
Summary: Fix default guide versions for head and 2.6
Product: OpenLDAP
Version: unspecified
Hardware: All
OS: All
Status: UNCONFIRMED
Keywords: needs_review
Severity: normal
Priority: ---
Component: documentation
Assignee: bugs(a)openldap.org
Reporter: quanah(a)openldap.org
Target Milestone: ---
The preamble file needs to be fixed in openldap head and the 2.6 release branch
to be correct.
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https://bugs.openldap.org/show_bug.cgi?id=10162
Issue ID: 10162
Summary: Fix for binary attributes data corruption in back-sql
Product: OpenLDAP
Version: unspecified
Hardware: All
OS: All
Status: UNCONFIRMED
Keywords: needs_review
Severity: normal
Priority: ---
Component: backends
Assignee: bugs(a)openldap.org
Reporter: dex.tracers(a)gmail.com
Target Milestone: ---
Created attachment 1006
--> https://bugs.openldap.org/attachment.cgi?id=1006&action=edit
Fix for binary attributes corruption on backed-sql
I've configured slapd to use back-sql (mariadb through odbc) and observed
issues with the BINARY data retrievals from the database. The length of the
attributes was properly reported, but the correct data inside was always 16384
bytes and after that point - some junk (usually filled-up with AAAAAAAA and
some other attributes data from memory).
During the debugging - I've noticed that:
- The MAX_ATTR_LEN (16384 bytes) is used to set the length of the data for
BINARY columns when SQLBindCol is done inside of the
"backsql_BindRowAsStrings_x" function
- After SQLFetch is done - data in row->cols[i] is fetched up to the specified
MAX_ATTR_LEN
- After SQLFetch is done - the correct data size (greater than MAX_ATTR_LEN) is
represented inside of the row->value_len
I'm assuming that slapd allocates the pointer in memory (row->cols[i]), fills
it with the specified amount of data (MAX_ATTR_LEN), but when forming the
actual attribute data - uses the length from row->value_len and so everything
from 16384 bytes position till row->value_len is just a junk from the memory
(uninitialized, leftovers, data from other variables).
After an investigation, I've find-out that:
- for BINARY or variable length fields - SQLGetData should be used
- SQLGetData supports chunked mode (if length is unknown) or full-read mode if
the length is known
- it could be used in pair with SQLBindCol after SQLFetch (!)
Since we have the correct data length inside of row->value_len, I've just added
the code to the backsql_get_attr_vals() function to overwrite the corrupted
data with the correct data by issuing SQLGetData request. And it worked -
binary data was properly retrieved and reported over LDAP!
My current concerns / help needed - I'm not very familiar with the memory
allocation/deallocation mechanisms, so I'm afraid that mentioned change can
lead to memory corruption (so far not observed).
Please review attached patch (testing was done on OPENLDAP_REL_ENG_2_5_13, and
applied on the master branch for easier review/application).
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https://bugs.openldap.org/show_bug.cgi?id=9211
Bug ID: 9211
Summary: Relax control is not consistently access-restricted
Product: OpenLDAP
Version: 2.4.49
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: ---
Component: slapd
Assignee: bugs(a)openldap.org
Reporter: ryan(a)openldap.org
Target Milestone: ---
The following operations can be performed by anyone having 'write' access (not
even 'manage') using the Relax control:
- modifying/replacing structural objectClass
- adding/modifying OBSOLETE attributes
Some operations are correctly restricted:
- adding/modifying NO-USER-MODIFICATION attributes marked as manageable
(Modification of non-conformant objects doesn't appear to be implemented at
all.)
In the absence of ACLs for controls, I'm of the opinion that all use of the
Relax control should require manage access. The Relax draft clearly and
repeatedly discusses its use cases in terms of directory _administrators_
temporarily relaxing constraints in order to accomplish a specific task.
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https://bugs.openldap.org/show_bug.cgi?id=10275
Issue ID: 10275
Summary: mdb_load could use a parameter to pass batch size
Product: LMDB
Version: 0.9.21
Hardware: All
OS: All
Status: UNCONFIRMED
Keywords: needs_review
Severity: normal
Priority: ---
Component: tools
Assignee: bugs(a)openldap.org
Reporter: gkwicker(a)amazon.com
Target Milestone: ---
Created attachment 1037
--> https://bugs.openldap.org/attachment.cgi?id=1037&action=edit
Patch to mdb_load.c in version 0.9.21
mdb_load is very slow when ingesting a large db. The attached patch (0.9.21
but will apply to other versions with modification) allows the user to pass a
batch size to be used instead of the default value of 100. Changing the batch
size to a larger value improves ingestion speed.
I, Gary Wicker, hereby place the following modifications to OpenLDAP Software
(and only these modifications) into the public domain. Hence, these
modifications may be freely used and/or redistributed for any purpose with or
without attribution and/or other notice.
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https://bugs.openldap.org/show_bug.cgi?id=9360
Issue ID: 9360
Summary: MDB_BAD_TXN: Transaction must abort, has a child, or
is invalid
Product: LMDB
Version: unspecified
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: ---
Component: liblmdb
Assignee: bugs(a)openldap.org
Reporter: spam(a)markandruth.co.uk
Target Milestone: ---
I have 2 python scripts writing to a database (lmdb 0.9.26, py-lmdb 0.98) and
5-10 lua processes (with lightningmdb module which uses lmdb 0.9.22) which are
long-running serving queries from the database.
The database seems fine, not corrupted, and the python writes still working all
the time. But periodically (perhaps 10-20% of the time), in a way I am unable
to reliably reproduce, when the lua starts up every time a query is issued txn
dbi_open returns "MDB_BAD_TXN: Transaction must abort, has a child, or is
invalid". A direct restart of the processes does not fix this issue, however
stopping lua+python and then starting again after a 5-20s wait usually fixes
the issue. This has been reproduced over multiple servers but I'm at a loss as
to how to debug this any further?
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https://bugs.openldap.org/show_bug.cgi?id=9208
Bug ID: 9208
Summary: LMDB feature request: variant of mdb_env_copy{,fd2}
that takes transaction as parameter
Product: LMDB
Version: unspecified
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: ---
Component: liblmdb
Assignee: bugs(a)openldap.org
Reporter: github(a)nicwatson.org
Target Milestone: ---
The mdb_env_copy* functions create a read transaction themselves to run the
backup on. New variants of these functions (one for mdb_env_copy2 and one for
mdb_env_copyfd2) would have a transaction parameter. This transaction would be
used instead of creating a new transaction.
Application code could use these new functions to synchronize consistent live
backups across multiple LMDB instances (potentially across multiple hosts).
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https://bugs.openldap.org/show_bug.cgi?id=10034
Issue ID: 10034
Summary: Assertion 'i < NUMKEYS(mp)' failed in
mdb_page_search_root()"
Product: LMDB
Version: 0.9.23
Hardware: Other
OS: Linux
Status: UNCONFIRMED
Keywords: needs_review
Severity: normal
Priority: ---
Component: liblmdb
Assignee: bugs(a)openldap.org
Reporter: 763280032(a)qq.com
Target Milestone: ---
We found that when lmdb is opened after OS startup and data is written to it,
lmdb will trigger abort probabilistically(Restart the OS 600 times will trigger
once);
We want to know what situation triggers this issue(Assertion 'i < NUMKEYS(mp)'
failed in mdb_page_search_root()); we want to know if there is a problem with
our usage;
Please Help Us
(gdb) x/8s 0x8baee988
0x8baee988: "8\373Բ\b\371Բmdb.c:5542: Assertion 'i < NUMKEYS(mp)' failed in
mdb_page_search_root()"
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https://bugs.openldap.org/show_bug.cgi?id=9475
Issue ID: 9475
Summary: Add support for MAP_POPULATE
Product: LMDB
Version: unspecified
Hardware: All
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: ---
Component: liblmdb
Assignee: bugs(a)openldap.org
Reporter: aa531811820(a)gmail.com
Target Milestone: ---
In some case (such as cloud computing platforms), the reading speed of large
files is very fast while the small files is very slow, and we have enough
memory, so we hope to prefetch the entire LMDB file into the memory during MMAP
through the MAP_POPULATE flag . According to our test, this is faster than
using readahead flag. Here are some test data:
# mmap with no readahead
read one sample: 0.2s
total time: 4800s
# mmap with readahead
read one sample: 0.0001s~0.03s
total time: 95.86s
# mmap with MAP_POPULATE
db init: 20s
read one sample: 0.0001s
total time: 78s
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