[ https://forge.continuent.org/jira/browse/SEQUOIA-1014?page=all ]
Stephane Giron resolved SEQUOIA-1014:
-------------------------------------
Assign To: Robert Hodges (was: Stephane Giron)
Resolution: Fixed
Fix Version: sequoia 2.10.10
Fixed in CVS
> If 2 controllers are too asynchronous, then a backend may be disabled because
> of a request failing on one controller and not the other one
> ------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: SEQUOIA-1014
> URL: https://forge.continuent.org/jira/browse/SEQUOIA-1014
> Project: Sequoia
> Type: Bug
> Components: Core
> Versions: Sequoia 2.10.9
> Reporter: Stephane Giron
> Assignee: Robert Hodges
> Fix For: sequoia 2.10.10
>
>
> This issue can be observed using mysql as backend (other database backends
> may show the same issue as well).
> It is related to the way the locks are taken into the backend and also to the
> effect of a statement failing inside a transaction.
> As an example,
> create table table1 (i integer)
> create table table2 (i integer)
> Then with 3 threads (C1, C2 and C3) :
> C1 : begin
> C1 : delete from table1
> C2 : begin
> C2 : delete from table2
> C2 : insert into table1 values(1)
> C3 : begin
> C3 : insert into table2 values(1)
> ...
> If one controller is about one minute late on the other, then the problem
> will show up :
> C2 : insert into table1 values(1) will fail because it can not get lock in
> mysql.
> => when failing, the request C3 : insert into table2 values(1) will be able
> to execute
> On the controller that is late, the first query will fail, causing the
> transaction to be aborted on the cluster.
> When the transaction will abort, the locks in mysql will be released.
> If the second request already failed on the first controller (the quicker),
> this same request will be able to succeed on the second one => the first
> backend will the be disabled (because a request failed whereas it succeeded
> on the other controller)
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