[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: back-bdb deadlocks?
David Boreham wrote:
For this current approach to work without interfering with db_archive,
we need a way to tell BDB that these transactions are read-only...
What you are looking for here is Isolation Level 2.
DB does not currently implement this.
But the next major release will.
Next major = 5.xx?
It turns out that a simple patch to BDB is all that's needed (see attached).
The corresponding patch to back-bdb is just this:
Index: cache.c
===================================================================
RCS file: /repo/OpenLDAP/pkg/ldap/servers/slapd/back-bdb/cache.c,v
retrieving revision 1.78
diff -u -r1.78 cache.c
--- cache.c 12 Jul 2004 18:02:24 -0000 1.78
+++ cache.c 17 Jul 2004 16:38:15 -0000
@@ -1186,7 +1186,7 @@
if ( ldap_pvt_thread_pool_getkey( ctx, ((char *)env)+1, &data,
NULL ) ) {
for ( i=0, rc=1; rc != 0 && i<4; i++ ) {
- rc = TXN_BEGIN( env, NULL, txn, 0 );
+ rc = TXN_BEGIN( env, NULL, txn,
DB_TXN_NOT_DURABLE );
if (rc) ldap_pvt_thread_yield();
}
if ( rc != 0) {
--
-- Howard Chu
Chief Architect, Symas Corp. Director, Highland Sun
http://www.symas.com http://highlandsun.com/hyc
Symas: Premier OpenSource Development and Support
Index: dbinc/db.in
===================================================================
RCS file: /var/CVSROOT/bdb42/dbinc/db.in,v
retrieving revision 1.1.1.1
retrieving revision 1.2
diff -u -r1.1.1.1 -r1.2
--- dbinc/db.in 25 Nov 2003 21:58:02 -0000 1.1.1.1
+++ dbinc/db.in 17 Jul 2004 16:07:23 -0000 1.2
@@ -839,6 +839,7 @@
#define TXN_NOWAIT 0x040 /* Do not wait on locks. */
#define TXN_RESTORED 0x080 /* Transaction has been restored. */
#define TXN_SYNC 0x100 /* Sync on prepare and commit. */
+#define TXN_NOLOG 0x200 /* Do not log this transaction. */
u_int32_t flags;
};
Index: txn/txn.c
===================================================================
RCS file: /var/CVSROOT/bdb42/txn/txn.c,v
retrieving revision 1.1.1.2
retrieving revision 1.2
diff -u -r1.1.1.2 -r1.2
--- txn/txn.c 17 Dec 2003 21:43:53 -0000 1.1.1.2
+++ txn/txn.c 17 Jul 2004 16:07:27 -0000 1.2
@@ -127,7 +127,7 @@
if ((ret = __db_fchk(dbenv,
"txn_begin", flags,
DB_DIRTY_READ | DB_TXN_NOWAIT |
- DB_TXN_NOSYNC | DB_TXN_SYNC)) != 0)
+ DB_TXN_NOSYNC | DB_TXN_SYNC | DB_TXN_NOT_DURABLE)) != 0)
return (ret);
if ((ret = __db_fcchk(dbenv,
"txn_begin", flags, DB_TXN_NOSYNC, DB_TXN_SYNC)) != 0)
@@ -193,6 +193,8 @@
F_SET(txn, TXN_SYNC);
if (LF_ISSET(DB_TXN_NOWAIT))
F_SET(txn, TXN_NOWAIT);
+ if (LF_ISSET(DB_TXN_NOT_DURABLE))
+ F_SET(txn, TXN_NOLOG);
if ((ret = __txn_begin_int(txn, 0)) != 0)
goto err;
@@ -328,7 +330,7 @@
* We should set this value when we write the first log record, not
* here.
*/
- if (DBENV_LOGGING(dbenv))
+ if (DBENV_LOGGING(dbenv) && !F_ISSET(txn, TXN_NOLOG))
__log_txn_lsn(dbenv, &begin_lsn, NULL, NULL);
else
ZERO_LSN(begin_lsn);