- openldap-bugs - openldap.org

(ITS#7782) [PATCH] contrib/slapd-modules/**/Makefile: LDAP_BUILD=$(LDAP_SRC) by default
by fumiyas＠osstech.co.jp 10 Jan '14

10 Jan '14

Full_Name: SATOH Fumiyasu Version: master OS: URL: ftp://ftp.openldap.org/incoming/0001-contrib-slapd-modules-Makefile-LDAP_BU… Submission from: (NULL) (240b:10:2640:bf0:2268:9dff:fec7:5444) The uploaded patch modifies contrib/slapd-modules/**/Makefile to set LDAP_BUILD to $(LDAP_SRC) by default instead of "../../.." (it's the same value of LDAP_SRC). This is bit useful in some minor situation. e.g., without this patch: make LDAP_SRC=/path/to/openldap-source-dir LDAP_BUILD=/path/to/openldap-source-dir with this patch: make LDAP_SRC=/path/to/openldap-source-dir

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(ITS#7781) constraint_attribute <attr> <size|count> cannot take 0
by fumiyas＠osstech.co.jp 10 Jan '14

10 Jan '14

Full_Name: SATOH Fumiyasu Version: master OS: URL: ftp://ftp.openldap.org/incoming/0001-constraint_attribute-attr-size-count-c… Submission from: (NULL) (240b:10:2640:bf0:2268:9dff:fec7:5444) The uploaded patch modifies slapo-constraint for constraint_attribute <attr> <size|count> can take 0. This patch depends on a patch attached in ITS#7780. http://www.openldap.org/its/index.cgi?findid=7780

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(ITS#7780) constraint_attribute <attr> <size|count> 0 cause segfault
by fumiyas＠osstech.co.jp 10 Jan '14

10 Jan '14

Full_Name: SATOH Fumiyasu Version: master OS: URL: ftp://ftp.openldap.org/incoming/0001-Fix-segfault-by-constraint_attribute-a… Submission from: (NULL) (240b:10:2640:bf0:2268:9dff:fec7:5444) If slapd.conf has the following config, slapd segfault at startup. overlay constraint constraint_attribute memberUid size 0 # or constraint_attribute memberUid count 0

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Re: (ITS#7771) liblmdb cursor issues
by h.b.furuseth＠usit.uio.no 09 Jan '14

09 Jan '14

Another problem when an xcursor's mc_pg[0] refers to a sub-page but has not been kept updated: The comparison 'mc_pg[i] == mp' below fails and mc_ki[i] does not get modified: if (m3->mc_pg[i] == mp && m3->mc_ki[i] >= mc->mc_ki[i]) { m3->mc_ki[i]++; } Then it's too late to fixup the sub-page pointer later, the xcursor refers to the wrong node in the sub-page. The above code is from mdb_cursor_put(), but there are other similar cases elsewhere. -- Hallvard

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Re: (ITS#7777) Filtering on modifyTimestamp is slower with index
by openldap-technical＠OpenLDAP.org 09 Jan '14

09 Jan '14

This is a cryptographically signed message in MIME format. --------------ms030505010104020400000608 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable The ITS is not for support requests. You should post things like this on = the openldap-technical mailing list. raphael.ouazana(a)linagora.com wrote: > I have a case where using modifyTimestamp index is far slower than with= no > index. > [..] > '(&(modifyTimestamp>=3D20131023163804Z)(modifyTimestamp<=3D201311231638= 04Z))' You might wanna read this old thread: http://www.openldap.org/lists/openldap-technical/201204/msg00116.html Try to use this filter instead: (&(modifyTimestamp>=3D20131023163804Z)(!(modifyTimestamp>=3D2013112316380= 4Z))) Ciao, Michael. --------------ms030505010104020400000608 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIFfzCC BXswggNjoAMCAQICAwxOfTANBgkqhkiG9w0BAQUFADB5MRAwDgYDVQQKEwdSb290IENBMR4w HAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmlu ZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZzAeFw0xMjEw MDIyMDE3MDlaFw0xNDEwMDIyMDE3MDlaMD8xGDAWBgNVBAMUD01pY2hhZWwgU3Ry9mRlcjEj MCEGCSqGSIb3DQEJARYUbWljaGFlbEBzdHJvZWRlci5jb20wggEiMA0GCSqGSIb3DQEBAQUA A4IBDwAwggEKAoIBAQDo2SKth5GhtaDrCyfGtyUG+/hAAa/J52L0NFN4SSRvTtdGf9HfWwwd NCtgae0TVGWk2lKDbXA9d5vmyIiRhuwxd90H6FLErhRBeB9G67qtw87E8WUoXt2DwPQEUTWV hqHpPadlmgFw3+i3TGQQTe3O3W9MMMd4GJNhObem2VGRuCD37OXnzBksTcq0FPJgcWAhe3d/ 0ItOkNWBqgq8Mf3p7WFBhaQ0a27BC/mKtH8fI3kPcS305imPRja69Msq3EwUZBc9ToVp6FRQ NYKjfOBybDUzVkmRZl3H8xutQP2w8Zxb8m5f7Q1BfLLrIFScfYvIDgOERxTCd4lab8+/09XH AgMBAAGjggFEMIIBQDAMBgNVHRMBAf8EAjAAMFYGCWCGSAGG+EIBDQRJFkdUbyBnZXQgeW91 ciBvd24gY2VydGlmaWNhdGUgZm9yIEZSRUUgaGVhZCBvdmVyIHRvIGh0dHA6Ly93d3cuQ0Fj ZXJ0Lm9yZzAOBgNVHQ8BAf8EBAMCA6gwQAYDVR0lBDkwNwYIKwYBBQUHAwQGCCsGAQUFBwMC BgorBgEEAYI3CgMEBgorBgEEAYI3CgMDBglghkgBhvhCBAEwMgYIKwYBBQUHAQEEJjAkMCIG CCsGAQUFBzABhhZodHRwOi8vb2NzcC5jYWNlcnQub3JnMDEGA1UdHwQqMCgwJqAkoCKGIGh0 dHA6Ly9jcmwuY2FjZXJ0Lm9yZy9yZXZva2UuY3JsMB8GA1UdEQQYMBaBFG1pY2hhZWxAc3Ry b2VkZXIuY29tMA0GCSqGSIb3DQEBBQUAA4ICAQC9ouXq3p/bDWMM4tBKgD3tl4HY5H0eECl8 q9/nqk0UL6YeWkrCiQdrDtNPW7DcGqNYtzdgtzmyTr1GhiAX+igrOjdk/ge5NRcQOpONK/4b zrmpQEcIUyxSSDKLWh211/kcFfxxLEiJ5teF4GL8Fc1qbrLP4+DCvJXWfYaaR5NLjZMqm2VP yKTv3qpXWnGohiRkGTwS/11QM2XCfIGdRsQT9a8mO4m2fn2tGPp2TEIoCLrDDrbGVeDWaOWB OIeTrp4wa3Q4OI6yCptJhEqKvjhV96IBRYgM76nTBqsqnDzwxExAyhhWiUS5DunRHOr/+NyF pUpD4883RBLO0g9kUEGOhtZNF1u+8zEL0YgMGvifAom9JEklLOXZuqj0MThypKs/3d/OyOQb 4gURnu6oZwcKZ7LskytWnlRKUxF6o0A8grtmyKkqe14TS7cQbg0NTaIYXPkHR+dfFmb3uEqn BBjvpJXFcEtWI2lQXC/ET+au991pK797ExBOmpQwjIn3SjiW80vw/UoL6DMvqY/6JhVhyNTP MJ2W5AX5kc27DIbVtVGZs8J4AYhuNALJUq9N9Ka7rPRj3RcYDrfehDLOkM5iMnarpmtuOpLK d1SvZhqj/0N/JWGIDpPSTkTFOPP6ZN9I9Rqyf+9NGqb2sjo4DkIiZcHxt735/GJLwus5KLBl 2DGCA6EwggOdAgEBMIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93 d3cuY2FjZXJ0Lm9yZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8G CSqGSIb3DQEJARYSc3VwcG9ydEBjYWNlcnQub3JnAgMMTn0wCQYFKw4DAhoFAKCCAfUwGAYJ KoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTQwMTA5MTUyNjEwWjAj BgkqhkiG9w0BCQQxFgQUhK88KTaaE97cUDowyV4g0ADaD78wbAYJKoZIhvcNAQkPMV8wXTAL BglghkgBZQMEASowCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIAgDAN BggqhkiG9w0DAgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKDCBkQYJKwYBBAGCNxAEMYGD MIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0Lm9y ZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJARYS c3VwcG9ydEBjYWNlcnQub3JnAgMMTn0wgZMGCyqGSIb3DQEJEAILMYGDoIGAMHkxEDAOBgNV BAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0Lm9yZzEiMCAGA1UEAxMZ Q0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJARYSc3VwcG9ydEBjYWNl cnQub3JnAgMMTn0wDQYJKoZIhvcNAQEBBQAEggEAsCtltB7mwSwYu91VjcKwVRXjP+SKJBXo e2uODXEsak3cHvHzRqvMSGAuj5LYyiLB6zCqJ2ra8MY/JtSI5+o1OHHrNO8kWwlgjaPzwyQo YTMeU9zVFXYiij247Ku1jepUT7WAxxiIjwNLJVt4OjpTmsDeOLG3z9f36bEIZLeaA9Dl5jUv 9m5oAqCZFnDNqVISv9MYAZGU8bB8EkxDb1ArSKt3ANFHL8e2ULYOnwExKgoqMyMPhpoepDhc AlPLktZvyq5Sxp4Y35J6Pw0NgJxExOC+iv03w6bSiAUNbSRBrMPXi2Tew7iCA4+Q87DeY5Nh X2fCUrJoStCDcoTm4Qi4OQAAAAAAAA== --------------ms030505010104020400000608--

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Re: (ITS#7779) Index and derived attribute bug
by yann.cezard＠univ-pau.fr 09 Jan '14

09 Jan '14

Sorry, it's a duplicate (#7778) due to a reload in web browser...

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(ITS#7779) Index and derived attribute bug
by yann.cezard＠univ-pau.fr 09 Jan '14

09 Jan '14

Full_Name: Yann Cezard Version: 2.4.38 OS: Debian GNU/Linux Wheezy / amd64 URL: ftp://ftp.openldap.org/incoming/Yann-Cezard-130109.tgz Submission from: (NULL) (2001:660:6701:14:225:64ff:fe92:685b) Hello, I hit a bug with the latest version of OpenLDAP (2.4.38) that was not present, at least in 2.4.17 (made a test on an older server that we were using before I discovered this). This happens on both lmdb and bdb backend (as we were using BDB before upgrading to 2.4.38, I tested with both on 2.4.38 to ensure that the problem was not LMDB related). The problem shows up when you delete the last attribute of en entry, which is derived from another attribute, which has an index on it (not easy to explain...). As an example (complete LDIF files - config/schema + data - provided on the incoming FTP), considering an attribute that is derived from the 'mail' attribute (which is defined in core.schema, and used in InetOrgPerson) : attributetype ( 1.3.6.1.4.1.7135.1.2.1.34 NAME 'supannAutreMail' DESC 'adresses mail non institutionnelles' SUP mail ) and an associated objectClass that use it (called supannPerson in the next example). Now place an index on mail : olcDbIndex: mail pres,eq,sub Now with an entry like this : dn: uid=test,ou=users,dc=example,dc=com uid: test sn: Test cn: Test objectClass: inetOrgPerson objectClass: organizationalPerson objectClass: person objectClass: top objectClass: supannPerson structuralObjectClass: inetOrgPerson entryUUID: 2699b5b4-0d7c-1033-9546-613643720ad1 creatorsName: cn=root,dc=example,dc=com createTimestamp: 20140109131736Z mail: test(a)example.com supannAutreMail: root(a)example.com supannAutreMail: user.test(a)example.com If you make a search with '(mail=*)', the entry matches : ############# $ ldapsearch -x -h ldap-test -b ou=users,dc=example,dc=com -D cn=root,dc=example,dc=com -w test -s one '(mail=*)' dn # extended LDIF # # LDAPv3 # base <ou=users,dc=example,dc=com> with scope oneLevel # filter: (mail=*) # requesting: dn # # test, users, example.com dn: uid=test,ou=users,dc=example,dc=com # search result search: 2 result: 0 Success ############## That's pretty normal. Now, remove both the supannAutreMail attributes from the entry. Run the same ldapsearch : ############## $ ldapsearch -x -h ldap-test -b ou=users,dc=example,dc=com -D cn=root,dc=example,dc=com -w test -s one '(mail=*)' dn # extended LDIF # # LDAPv3 # base <ou=users,dc=example,dc=com> with scope oneLevel # filter: (mail=*) # requesting: dn # # search result search: 2 result: 0 Success # numResponses: 1 ############## The entry doesn't match anymore... But still it has a mail attribute : ############## $ ldapsearch -x -h ldap-test -b ou=users,dc=example,dc=com -D cn=root,dc=example,dc=com -w test -s one '(uid=test)' mail # extended LDIF # # LDAPv3 # base <ou=users,dc=example,dc=com> with scope oneLevel # filter: (uid=test) # requesting: mail # # test, users, example.com dn: uid=test,ou=users,dc=example,dc=com mail: test(a)example.com # search result search: 2 result: 0 Success # numResponses: 2 # numEntries: 1 ############## The only ways to make the '(mail=*)' filter matches again the modified entry, is to modify the mail attribute, or to run slapindex. If you remove the index on the mail attribute, then there is no such problem. It only happens when deleting all/the last derived attributes (supannAutreMail here) from the entry. Sounds to me like a bug, isn't it ? Regards.

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(ITS#7778) Index and derived attribute bug
by yann.cezard＠univ-pau.fr 09 Jan '14

09 Jan '14

Full_Name: Yann Cezard Version: 2.4.38 OS: Debian GNU/Linux Wheezy / amd64 URL: ftp://ftp.openldap.org/incoming/Yann-Cezard-130109.tgz Submission from: (NULL) (2001:660:6701:14:225:64ff:fe92:685b) Hello, I hit a bug with the latest version of OpenLDAP (2.4.38) that was not present, at least in 2.4.17 (made a test on an older server that we were using before I discovered this). This happens on both lmdb and bdb backend (as we were using BDB before upgrading to 2.4.38, I tested with both on 2.4.38 to ensure that the problem was not LMDB related). The problem shows up when you delete the last attribute of en entry, which is derived from another attribute, which has an index on it (not easy to explain...). As an example (complete LDIF files - config/schema + data - provided on the incoming FTP), considering an attribute that is derived from the 'mail' attribute (which is defined in core.schema, and used in InetOrgPerson) : attributetype ( 1.3.6.1.4.1.7135.1.2.1.34 NAME 'supannAutreMail' DESC 'adresses mail non institutionnelles' SUP mail ) and an associated objectClass that use it (called supannPerson in the next example). Now place an index on mail : olcDbIndex: mail pres,eq,sub Now with an entry like this : dn: uid=test,ou=users,dc=example,dc=com uid: test sn: Test cn: Test objectClass: inetOrgPerson objectClass: organizationalPerson objectClass: person objectClass: top objectClass: supannPerson structuralObjectClass: inetOrgPerson entryUUID: 2699b5b4-0d7c-1033-9546-613643720ad1 creatorsName: cn=root,dc=example,dc=com createTimestamp: 20140109131736Z mail: test(a)example.com supannAutreMail: root(a)example.com supannAutreMail: user.test(a)example.com If you make a search with '(mail=*)', the entry matches : ############# $ ldapsearch -x -h ldap-test -b ou=users,dc=example,dc=com -D cn=root,dc=example,dc=com -w test -s one '(mail=*)' dn # extended LDIF # # LDAPv3 # base <ou=users,dc=example,dc=com> with scope oneLevel # filter: (mail=*) # requesting: dn # # test, users, example.com dn: uid=test,ou=users,dc=example,dc=com # search result search: 2 result: 0 Success ############## That's pretty normal. Now, remove both the supannAutreMail attributes from the entry. Run the same ldapsearch : ############## $ ldapsearch -x -h ldap-test -b ou=users,dc=example,dc=com -D cn=root,dc=example,dc=com -w test -s one '(mail=*)' dn # extended LDIF # # LDAPv3 # base <ou=users,dc=example,dc=com> with scope oneLevel # filter: (mail=*) # requesting: dn # # search result search: 2 result: 0 Success # numResponses: 1 ############## The entry doesn't match anymore... But still it has a mail attribute : ############## $ ldapsearch -x -h ldap-test -b ou=users,dc=example,dc=com -D cn=root,dc=example,dc=com -w test -s one '(uid=test)' mail # extended LDIF # # LDAPv3 # base <ou=users,dc=example,dc=com> with scope oneLevel # filter: (uid=test) # requesting: mail # # test, users, example.com dn: uid=test,ou=users,dc=example,dc=com mail: test(a)example.com # search result search: 2 result: 0 Success # numResponses: 2 # numEntries: 1 ############## The only ways to make the '(mail=*)' filter matches again the modified entry, is to modify the mail attribute, or to run slapindex. If you remove the index on the mail attribute, then there is no such problem. It only happens when deleting all/the last derived attributes (supannAutreMail here) from the entry. Sounds to me like a bug, isn't it ? Regards.

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(ITS#7777) Filtering on modifyTimestamp is slower with index
by raphael.ouazana＠linagora.com 09 Jan '14

09 Jan '14

Full_Name: Raphael Ouazana Version: 2.4.38 OS: Linux URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (88.173.78.196) Hi, I have a case where using modifyTimestamp index is far slower than with no index. First with indexing: ###Caching $ time ldapsearch -b <people> -D <manager> -W # search result search: 2 result: 0 Success # numResponses: 293886 # numEntries: 293885 real 0m12.153s user 0m7.805s sys 0m1.888s ### Request $ time ldapsearch -b <people> -D <manager> -W '(&(modifyTimestamp>=20131023163804Z)(modifyTimestamp<=20131123163804Z))' # search result search: 2 result: 0 Success # numResponses: 24277 # numEntries: 24276 real 0m23.441s user 0m0.554s sys 0m0.073s Now without modifyTimestamp index: ###Caching $ time ldapsearch -b <people> -D <manager> -W # search result search: 2 result: 0 Success # numResponses: 293886 # numEntries: 293885 real 0m11.627s user 0m7.354s sys 0m1.772s ### Request $ time ldapsearch -b <people> -D <manager> -W '(&(modifyTimestamp>=20131023163804Z)(modifyTimestamp<=20131123163804Z))' # search result search: 2 result: 0 Success # numResponses: 24277 # numEntries: 24276 real 0m0.701s user 0m0.569s sys 0m0.070s As you can see, without indexing the request takes less than 1s, while with index it takes more than 20s. I think it is not the expected result. Regards, Raphaël Ouazana.

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Re: (ITS#7774) LMDB assertion failure during Postfix cache cleanup
by wietse＠porcupine.org 08 Jan '14

08 Jan '14

Hallvard Breien Furuseth: > On 2014-01-08 18:23, Howard Chu wrote: > > Wietse Venema wrote: > >> Hallvard Breien Furuseth: > >>> Process A may see garbage data. > > > > This is wrong. The fcntl locks will definitely prevent two processes > > from interfering with each other. The reason this bug occurs is > > because fcntl locks cannot prevent two transactions within a single > > process from stomping on each other. > > Hmm. OK, after some discussion with Howard: > > This was so with Howard's original code, it wrapped each mdb_get() in > a transaction. postfix-2.11-20131228/src/util/slmdb.c breaks this by > preserving the read transaction until an error happens which is bad > enough for the code to notice. The Postfix first/next iterator has always used a long-term read transaction, ever since the first LMDB patch for Postfix. This broke with the switch to MDB_NOLOCK. > Locks around cursors are pointless as well as insufficient from > lmdb's point of view. It is transactions which must be protected. With MDB_NOLOCK the cursor's read transaction must be protected, and it must be closed before returning the (key, value) to the caller. Wietse

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Re: (ITS#7774) LMDB assertion failure during Postfix cache cleanup
by h.b.furuseth＠usit.uio.no 08 Jan '14

08 Jan '14

On 2014-01-08 18:23, Howard Chu wrote: > Wietse Venema wrote: >> Hallvard Breien Furuseth: >>> Process A may see garbage data. > > This is wrong. The fcntl locks will definitely prevent two processes > from interfering with each other. The reason this bug occurs is > because fcntl locks cannot prevent two transactions within a single > process from stomping on each other. Hmm. OK, after some discussion with Howard: This was so with Howard's original code, it wrapped each mdb_get() in a transaction. postfix-2.11-20131228/src/util/slmdb.c breaks this by preserving the read transaction until an error happens which is bad enough for the code to notice. Locks around cursors are pointless as well as insufficient from lmdb's point of view. It is transactions which must be protected. -- Hallvard

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Re: (ITS#7774) LMDB assertion failure during Postfix cache cleanup
by hyc＠symas.com 08 Jan '14

08 Jan '14

Wietse Venema wrote: > Hallvard Breien Furuseth: >> Wietse Venema writes: >>> (...) what happens when the two above activities happen >>> in different processes? That is, process A (opens the database with >>> MDB_NOLOCK. opens a cursor, and walks the database without making >>> any changes to it), while process B opens the same database with >>> MDB_NOLOCK and performs the delete transactions. >>> >>> Will the process A cursor read transaction trigger an assertion due >>> to the process B delete transactions? If not, why not? >> >> Process A may see garbage data. This is wrong. The fcntl locks will definitely prevent two processes from interfering with each other. The reason this bug occurs is because fcntl locks cannot prevent two transactions within a single process from stomping on each other. This can result in an assert(), a >> segfault or other misbehavior. Just like if you had process A == B. >> With MDB_NOLOCK, after a write transaction commits you need to >> end existing read-only transactions before starting a new writer. >> (Well, it's a bit looser than that, but that's a simple rule.) > > Thanks for confirming my suspicion. I think that the correct option > then is to use only short-lived cursor read transactions within > fcntl()-protected blocks and to save/restore the previous cursor > key where applicable. > > Wietse > -- -- 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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Re: (ITS#7774) LMDB assertion failure during Postfix cache cleanup
by h.b.furuseth＠usit.uio.no 08 Jan '14

08 Jan '14

I write: > Maybe MDB_NOLOCK should have kept the lockfile and reader table, and > just omitted the mutexes/semaphores that synchronize transactions. Duh, nevermind. As Howard reminded me, that'd require readers to have write access to the lockfile, which was the problem which started all this. -- Hallvard

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Re: (ITS#7774) LMDB assertion failure during Postfix cache cleanup
by wietse＠porcupine.org 08 Jan '14

08 Jan '14

Hallvard Breien Furuseth: > Wietse Venema writes: > > (...) what happens when the two above activities happen > > in different processes? That is, process A (opens the database with > > MDB_NOLOCK. opens a cursor, and walks the database without making > > any changes to it), while process B opens the same database with > > MDB_NOLOCK and performs the delete transactions. > > > > Will the process A cursor read transaction trigger an assertion due > > to the process B delete transactions? If not, why not? > > Process A may see garbage data. This can result in an assert(), a > segfault or other misbehavior. Just like if you had process A == B. > With MDB_NOLOCK, after a write transaction commits you need to > end existing read-only transactions before starting a new writer. > (Well, it's a bit looser than that, but that's a simple rule.) Thanks for confirming my suspicion. I think that the correct option then is to use only short-lived cursor read transactions within fcntl()-protected blocks and to save/restore the previous cursor key where applicable. Wietse

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Re: (ITS#7774) LMDB assertion failure during Postfix cache cleanup
by h.b.furuseth＠usit.uio.no 08 Jan '14

08 Jan '14

Wietse Venema writes: > (...) what happens when the two above activities happen > in different processes? That is, process A (opens the database with > MDB_NOLOCK. opens a cursor, and walks the database without making > any changes to it), while process B opens the same database with > MDB_NOLOCK and performs the delete transactions. > > Will the process A cursor read transaction trigger an assertion due > to the process B delete transactions? If not, why not? Process A may see garbage data. This can result in an assert(), a segfault or other misbehavior. Just like if you had process A == B. With MDB_NOLOCK, after a write transaction commits you need to end existing read-only transactions before starting a new writer. (Well, it's a bit looser than that, but that's a simple rule.) Because: A read-only transaction needs a frozen, valid snapshot of the DB. Normally it registers itself in the lockfile, so writers know to not touch the pages that make up that snapshot. MDB_NOLOCK disables the lockfile, leaving those pages unprotected from writers. Maybe MDB_NOLOCK should have kept the lockfile and reader table, and just omitted the mutexes/semaphores that synchronize transactions. OTOH mapsize changes in B are not a problem for _existing_ transactions in A, since it was actually the accompanying map _address_ change which broke existing transactions. But if A tries to begin new transactions, mdb_txn_begin() may soon fail with MDB_MAP_RESIZED until A also resizes. -- Hallvard

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Re: (ITS#7774) LMDB assertion failure during Postfix cache cleanup
by wietse＠porcupine.org 08 Jan '14

08 Jan '14

This is a follow-up question, not a request to reopen the issue. It is about what happens when different processes open the same database with MDB_NOLOCK, and then perform the exact same operations that were the subject of ITS#7774. Brief summary of ITS#7774: when an LMDB database is opened with MDB_NOLOCK, a long-lived cursor's read transaction triggers an assertion when the same process performs a delete transaction on a different database element. This happened when walking an LMDB-based cache to remove "expired" entries. The application uses fcntl() shared locks around cursor_get() and mdb_get() including all related MDB operations, and it uses fcntl() exclusive locks around mdb_put() and mdb_del() including all related MDB operations. The solution was to close the long-lived cursor's read transaction before the delete operation. Now my question: what happens when the two above activities happen in different processes? That is, process A (opens the database with MDB_NOLOCK. opens a cursor, and walks the database without making any changes to it), while process B opens the same database with MDB_NOLOCK and performs the delete transactions. Will the process A cursor read transaction trigger an assertion due to the process B delete transactions? If not, why not? Wietse

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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by wietse＠porcupine.org 08 Jan '14

08 Jan '14

Quanah Gibson-Mount: > --On Tuesday, January 07, 2014 10:03 PM +0000 wietse(a)porcupine.org wrote: > > > Having obtained the patch off-list, I confirm that this call-back > > feature works satisfactorily, and that this ITS can be closed. > > > > I am looking forward to the next LMDB release. > > Hi Wietse, > > I'm currently working with the dev team to get a new release out in the > next week or so. Please do not speed up the process at the cost of code quality. I'm ready to turn on support for LMDB >= 0.9.11 in Postfix 2.11.0, as long as I know that this ITS will be addressed in 0.9.11. Wietse

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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by quanah＠zimbra.com 07 Jan '14

07 Jan '14

--On Tuesday, January 07, 2014 10:03 PM +0000 wietse(a)porcupine.org wrote: > Having obtained the patch off-list, I confirm that this call-back > feature works satisfactorily, and that this ITS can be closed. > > I am looking forward to the next LMDB release. Hi Wietse, I'm currently working with the dev team to get a new release out in the next week or so. --Quanah -- Quanah Gibson-Mount Architect - Server Zimbra, Inc. -------------------- Zimbra :: the leader in open source messaging and collaboration

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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by wietse＠porcupine.org 07 Jan '14

07 Jan '14

Wietse Venema: > Hallvard Breien Furuseth: > > Pushed to mdb.master. > > > > void assert_callback(MDB_env *env, const char *msg) { > > void *ctx = mdb_env_get_userctx(env); > > ...; > > } > > > > mdb_env_create(&env); > > mdb_env_set_userctx(env, ctx); > > mdb_env_set_assert(env, assert_callback); Having obtained the patch off-list, I confirm that this call-back feature works satisfactorily, and that this ITS can be closed. I am looking forward to the next LMDB release. Wietse

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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by wietse＠porcupine.org 07 Jan '14

07 Jan '14

Hallvard Breien Furuseth: > Pushed to mdb.master. > > void assert_callback(MDB_env *env, const char *msg) { > void *ctx = mdb_env_get_userctx(env); > ...; > } > > mdb_env_create(&env); > mdb_env_set_userctx(env, ctx); > mdb_env_set_assert(env, assert_callback); 1) Where can I find this patch? I would like to confirm that the code works without surprises. 2) Will this code be part of LMDB 0.9.11 (or some other number)? That allows me to use the correct #ifdef in my code. 3) What is the expected release time frame for this code? If it's close enough to the Postfix 2.11 stable release late January, then it can include LMDB support. Wietse

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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by h.b.furuseth＠usit.uio.no 07 Jan '14

07 Jan '14

Pushed to mdb.master. void assert_callback(MDB_env *env, const char *msg) { void *ctx = mdb_env_get_userctx(env); ...; } mdb_env_create(&env); mdb_env_set_userctx(env, ctx); mdb_env_set_assert(env, assert_callback); -- Hallvard

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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by h.b.furuseth＠usit.uio.no 05 Jan '14

05 Jan '14

On 2014-01-05 20:03, hyc(a)symas.com wrote: > I made this comment to Hallvard as well. It should be: > > MDB_assert_func * > mdb_env_set_assert(MDB_env *env, MDB_assert_func *func, void *info); Yes, I missed that. Hadn't intended to take this ITS into such a detour. Maybe such a context argument can be useful outside asserts too though, like a Python wrapper which wants the Python element wrapping the MDB_env of a given txn. If so, instead of passing the context to mdb_env_set_assert(): int mdb_env_set_userctx(env, void *ctx); void *mdb_env_get_userctx(env); assert() could still pass it out to the assert fallback. -- Hallvard

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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by hyc＠symas.com 05 Jan '14

05 Jan '14

wietse(a)porcupine.org wrote: > Wietse Venema: >>> env can be NULL. mdb_env_set_assert(env,cb) also sets a static >>> variable with the callback for the asserts which do not know of an >>> env. Could throw away that part later. Currently it only applies >>> to one assert(). >>> >>> The branch also invalidates a transaction on any page allocation >>> error, since the callers do not always clean up afterwards. Too >>> aggressive, can be reverted after updating the callers. But for >>> now it means MDB_MAP_FULL & co won't let the user commit an >>> inconsistent transaction. >> >> Thanks, this is more improvement than I asked for. I don't want to >> slip my schedule, and to avoid last-minute surprises, I will postpone >> the review and impact test of these improvements after the stable >> Postfix release 2-3 weeks from today. > > It looks like you are switching from a stop-gap fix (bare-bones > call-back) to a more permanent solution. > > In that case I must mention again that I need to register not only > a call-back function pointer but also a void* pointer that is > returned to me at call-back time. > > Getting the MDB_env at call-back time does not help me at all, > because my programs open many databases (including non-LMDB). I made this comment to Hallvard as well. It should be: MDB_assert_func * mdb_env_set_assert(MDB_env *env, MDB_assert_func *func, void *info); with the info being passed thru to the callback. > To find out which database is affected I need my own pointer to my > own (DICT) object that encapsulates the LMDB database. Then I can > decide if the problem is with a disposable cache. in which case the > program can continue with degraded performance. > > Wietse > > > -- -- 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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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by wietse＠porcupine.org 05 Jan '14

05 Jan '14

Wietse Venema: > > env can be NULL. mdb_env_set_assert(env,cb) also sets a static > > variable with the callback for the asserts which do not know of an > > env. Could throw away that part later. Currently it only applies > > to one assert(). > > > > The branch also invalidates a transaction on any page allocation > > error, since the callers do not always clean up afterwards. Too > > aggressive, can be reverted after updating the callers. But for > > now it means MDB_MAP_FULL & co won't let the user commit an > > inconsistent transaction. > > Thanks, this is more improvement than I asked for. I don't want to > slip my schedule, and to avoid last-minute surprises, I will postpone > the review and impact test of these improvements after the stable > Postfix release 2-3 weeks from today. It looks like you are switching from a stop-gap fix (bare-bones call-back) to a more permanent solution. In that case I must mention again that I need to register not only a call-back function pointer but also a void* pointer that is returned to me at call-back time. Getting the MDB_env at call-back time does not help me at all, because my programs open many databases (including non-LMDB). To find out which database is affected I need my own pointer to my own (DICT) object that encapsulates the LMDB database. Then I can decide if the problem is with a disposable cache. in which case the program can continue with degraded performance. Wietse

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Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record
by wietse＠porcupine.org 05 Jan '14

05 Jan '14

Hallvard Breien Furuseth: > Drafted a branch "mdb/assert" in > <http://folk.uio.no/hbf/OpenLDAP/mdb.git/> and on Ada, based > roughly on Howard's original message to you. I didn't know about > that at first, which has caused some confusion. > > So the callback usually receives an env after all, and a NULL > context since I don't know what Howard intended there. > > Howard, do I push this? Feel free to grab it and tweak a bit:) > > env can be NULL. mdb_env_set_assert(env,cb) also sets a static > variable with the callback for the asserts which do not know of an > env. Could throw away that part later. Currently it only applies > to one assert(). > > The branch also invalidates a transaction on any page allocation > error, since the callers do not always clean up afterwards. Too > aggressive, can be reverted after updating the callers. But for > now it means MDB_MAP_FULL & co won't let the user commit an > inconsistent transaction. Thanks, this is more improvement than I asked for. I don't want to slip my schedule, and to avoid last-minute surprises, I will postpone the review and impact test of these improvements after the stable Postfix release 2-3 weeks from today. Wietse

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