database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-27 18:02:13 +03:00
Code Activity

MDEV-7825: Parallel replication race condition on gco->flags, possibly resulting in slave hang

Browse Source 
The patch for optimistic parallel replication as a memory optimisation moved
the gco->installed field into a bit in gco->flags. However, that is just plain
wrong. The gco->flags field is owned by the SQL driver thread, but
gco->installed is used by the worker threads, so this will cause a race
condition.

The user-visible problem might be conflicts between transactions and/or slave
threads hanging.

So revert this part of the optimistic parallel replication patch, going back
to using a separate field gco->installed like in 10.0.
This commit is contained in:
Kristian Nielsen
2015-03-24 16:33:51 +01:00
parent ec68494beb
commit bd2ae787ea
2 changed files with 7 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
sql/rpl_parallel.h
View File

@ -66,7 +66,8 @@ struct group_commit_orderer {
This flag is set when this GCO has been installed into the next_gco pointer
of the previous GCO.
*/
static const uint8 INSTALLED = 0x01;
bool installed;
/*
This flag is set for a GCO in which we have event groups with multiple
different commit_id values from the master. This happens when we
@ -77,13 +78,13 @@ struct group_commit_orderer {
of current commit_id, as DDL is not safe to speculatively apply in parallel
with prior event groups.
*/
static const uint8 MULTI_BATCH = 0x02;
static const uint8 MULTI_BATCH = 0x01;
/*
This flag is set for a GCO that contains DDL. If set, it forces a switch to
a new GCO upon seeing a new commit_id, as DDL is not safe to speculatively
replicate in parallel with subsequent transactions.
*/
static const uint8 FORCE_SWITCH = 0x04;
static const uint8 FORCE_SWITCH = 0x02;
uint8 flags;
};