tom.bjorkholm@aastra.com wrote:

Full_Name: Stelios Grigoriadis & Tom Björkholm Version: 2.3.39 OS: Novell SLES 10 URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (194.237.142.7)

We get a lot of DB_LOCK_DEADLOCK when using client programs that for a period of time continuously writes to OpenLDAP. Version is 2.3.39.

The information added is of the form: ebcmdCustomer=0+ebcmdDir=220xx,ou=AuthCodes,ebcmdVersion=0,ebcmdProduct=ebcmd,dc=example,dc=com where xx varies.

Snippet of the output: Mar 27 13:03:21 ldapt1 slapd[7589]: => bdb_dn2id_add: subtree (ebcmdCustomer=0+ebcmdDir=22037,ou=authcodes,ebcmdVersion=0,ebcmdProduct=ebcmd,dc=example,dc=com) put failed: -30995 Mar 27 13:03:26 ldapt1 slapd[7589]: => bdb_idl_insert_key: c_put id failed: DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock (-30995) Mar 27 13:03:26 ldapt1 slapd[7589]: => bdb_dn2id_add: parent (ou=authcodes,ebcmdVersion=0,ebcmdProduct=ebcmd,dc=example,dc=com) insert failed: -30995 Mar 27 13:03:28 ldapt1 slapd[7589]: => bdb_idl_insert_key: c_put id failed: DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock (-30995) Mar 27 13:03:28 ldapt1 slapd[7589]: => bdb_dn2id_add: parent (ou=authcodes,ebcmdVersion=0,ebcmdProduct=ebcmd,dc=example,dc=com) insert failed: -30995 Mar 27 13:03:36 ldapt1 slapd[7589]: => bdb_idl_insert_key: c_put id failed: DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock (-30995) Mar 27 13:03:36 ldapt1 slapd[7589]: => bdb_dn2id_add: parent (ou=authcodes,ebcmdVersion=0,ebcmdProduct=ebcmd,dc=example,dc=com) insert failed: -30995 Mar 27 13:03:38 ldapt1 slapd[7589]: => bdb_idl_insert_key: c_put id failed: DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock (-30995)

We've temporarily fixed the problem by introducing a static mutex before any add/update operation. By doing so, we have effectively serialized the add/update operations from within slapd. This is just intended as a temporary solution as we hope the issue will be resolved in future releases.

The patch:

# This patch file is derived from OpenLDAP Software. All of the modifications to OpenLDAP Software # represented in the following patch(es) were developed by Stelios Grigoriadis stelios.xx.grigoriadis@ericsson.com. # These modifications are not subject to any license of Ericsson AB.

# I, Stelios Grigoriadis, 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.

# Bug Fix - This patch fixes the bug ITS#5133. # The fix works as follows. A periodic check in the runqueue (called do_mastercheck). The intervall is determined by # a slapd.conf parameter (mastercheckint) in the syncrepl section and is optional. If it's not specified, it's not # inserted in the runqueue.

--- servers/slapd/connection.c 2007-06-15 01:49:38.000000000 +0200 +++ connection.c 2008-06-10 16:30:08.000000000 +0200 @@ -1052,19 +1052,24 @@ /* FIXME: returns 0 in case of failure */ ldap_pvt_mp_add_ulong(slap_counters.sc_ops_initiated, 1); ldap_pvt_thread_mutex_unlock( &slap_counters.sc_ops_mutex ); + static pthread_mutex_t op_upd_mutex = PTHREAD_MUTEX_INITIALIZER;

+ int upd_tag=0; op->o_threadctx = ctx; #ifdef LDAP_DEVEL op->o_tid = ldap_pvt_thread_pool_tid( ctx ); #endif /* LDAP_DEVEL */

switch ( tag ) { - case LDAP_REQ_BIND: - case LDAP_REQ_UNBIND: case LDAP_REQ_ADD: case LDAP_REQ_DELETE: case LDAP_REQ_MODDN: case LDAP_REQ_MODIFY: + ldap_pvt_thread_mutex_lock( &op_upd_mutex ); + upd_tag=1; + break; + case LDAP_REQ_BIND: + case LDAP_REQ_UNBIND: case LDAP_REQ_COMPARE: case LDAP_REQ_SEARCH: case LDAP_REQ_ABANDON: @@ -1178,6 +1183,10 @@

connection_resched( conn ); ldap_pvt_thread_mutex_unlock( &conn->c_mutex ); + if (upd_tag) { + ldap_pvt_thread_mutex_unlock( &op_upd_mutex ); + } + return NULL; }