At Tue, 8 Jun 2021 08:45:24 +0000, "tsunakawa.ta...@fujitsu.com" <tsunakawa.ta...@fujitsu.com> wrote in > From: Kyotaro Horiguchi <horikyota....@gmail.com> > > I think the discussion is based the behavior that any process that is > > responsible for finishing the 2pc-commit continue retrying remote > > commits until all of the remote-commits succeed. > > Thank you for coming back. We're talking about the first attempt to prepare > and commit in each transaction, not the retry case.
If we accept each elementary-commit (via FDW connection) to fail, the parent(?) there's no way the root 2pc-commit can succeed. How can we ignore the fdw-error in that case? > > > Throws: HeuristicMixedException > > > Thrown to indicate that a heuristic decision was made and that some > > relevant updates have been > > > committed while others have been rolled back. > > > I'm not sure about how JTA works in detail, but doesn't > > UserTransaction.commit() return HeuristicMixedExcpetion when some of > > relevant updates have been committed but other not? Isn't it the same > > state with the case where some of the remote servers failed on > > remote-commit while others are succeeded? > > No. Taking the description literally and considering the relevant XA > specification, it's not about the remote commit failure. The remote server > is not allowed to fail the commit once it has reported successful prepare, > which is the contract of 2PC. HeuristicMixedException is about the manual > resolution, typically by the DBA, using the DBMS-specific tool or the > standard commit()/rollback() API. Mmm. The above seems as if saying that 2pc-comit does not interact with remotes. The interface contract does not cover everything that happens in the real world. If remote-commit fails, that is just an issue outside of the 2pc world. In reality remote-commit may fail for all reasons. https://www.ibm.com/docs/ja/db2-for-zos/11?topic=support-example-distributed-transaction-that-uses-jta-methods > } catch (javax.transaction.xa.XAException xae) > { // Distributed transaction failed, so roll it back. > // Report XAException on prepare/commit. This suggests that both XAResoruce.prepare() and commit() can throw a exception. > > (I guess that > > UserTransaction.commit() would throw RollbackException if > > remote-prepare has been failed for any of the remotes.) > > Correct. So UserTransaction.commit() does not throw the same exception if remote-commit fails. Isn't the HeuristicMixedExcpetion the exception thrown in that case? regards. -- Kyotaro Horiguchi NTT Open Source Software Center
