andrei.el...@pp.inet.fi writes: > First the parent errros out goes to `finish_event_group()' but it's > possible it does not have yet the child in its `subsequent_commits_list'
> So I understood so far that the retrying worker needs to check > `stop_on_error_sub_id' that effectively reflects the error status. Agree, the basic fix looks correct, of checking stop_on_error_sub_id. And yes, there are probably cases where after stop_on_error_sub_id is set, earlier transactions are aborted early without setting up the subsequent-transaction-chain, so that wait_for_prior_commit cannot be relied upon, and stop_on_error_sub_id must be checked. So again, nice catch, this would be nasty to try and debug from errors seen only in a user's setup. I am only wondering about two points, if there is something that needs to be adjusted in the patch around the error exit after stop_on_error_sub_id, or perhaps something else not yet understood going on: Number one: >>> + if (!rgi->worker_error) >>> + rgi->worker_error= 1; >>> + } >> >> I would have expected an abort (goto err) here (or well just below, after >> unlocking the mutex). Is this not needed, and if so, why not? > > I left it to upcoming (in 2 lines) THD::wait_for_prior_commit(). It > takes care to check out `worker_error'. > > int wait_for_prior_commit(THD *thd) > { > /* > Quick inline check, to avoid function call and locking in the common > case > where no wakeup is registered, or a registered wait was already > signalled. > */ > if (waitee) > return wait_for_prior_commit2(thd); > else > { > if (wakeup_error) > my_error(ER_PRIOR_COMMIT_FAILED, MYF(0)); > return wakeup_error; > } > } > > No waitee is guaranteed as this worker skipped > `register_wait_for_prior_event_group_commit()'. Sorry, I don't get it. wait_for_prior_commit() checks thd->wait_for_commit_ptr->wakeup_error, not rgi->worker_error? wait_for_prior_commit() doesn't have access to rgi. > list. And that's how the parent's `wakeup_error' never reaches the > child. This is certainly the case when a child retries after a temp > failure. In the test condition the child's `worker_error' is zero, but > if a non-zero case `worker_error' gets cleared anyway through > `unregister_wait_for_prior_commit()'. Isn't there some confusion here? Between "wakeup_error", which sits inside struct wait_for_commit, and indicates that a prior event group failed. And "worker_error" in rpl_group_info, which indicates that _this_ event group failed, and is used to remember to do proper error cleanup inside the worker thread? Number two: > You must mean the retrying worker stops doing it optimistically. I saw that. > But I saw through logs that at times a worker > could re-try about the number of worker pool size. > Perhaps this unrestrained behaviour was caused by lack of a check of the > current patch. Yes, that is what I mean. And yes, the underlying bug with missing check on stop_on_error_sub_id might have caused this as a secondary effect. My point was just that users should not need to set a high retry count just from using parallel replication (remember, several thousand worker threads have been used with success on production data). So if this is necessary in a test case, it might indicate a problem with the code... - Kristian. _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : maria-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp