CommitWindowId could be computed from the existing checkpoints. That solution still needs purge to be done after commitWindowId is confirmed to be saved in Stram state. Without ths the commitWindowId computed from the checkpoints may have some checkpoints missing.
Thks Amol E:a...@datatorrent.com | M: 510-449-2606 | Twitter: @*amolhkekre* www.datatorrent.com | apex.apache.org *Join us at Apex Big Data World-San Jose <http://www.apexbigdata.com/san-jose.html>, April 4, 2017!* [image: http://www.apexbigdata.com/san-jose-register.html] <http://www.apexbigdata.com/san-jose-register.html> On Wed, Mar 1, 2017 at 12:36 PM, Pramod Immaneni <pra...@datatorrent.com> wrote: > Can't the commitedWindowId be calculated by looking at the physical plan > and the existing checkpoints? > > On Wed, Mar 1, 2017 at 5:34 AM, Tushar Gosavi <tus...@apache.org> wrote: > > > Help Needed for APEXCORE-619 > > > > Issue : When application is relaunched after long time with stateless > > opeartors at the end of the DAG, the stateless operators starts with a > very > > high windowId. In this case the stateless operator ignors all the data > > received till upstream operator catches up with it. This breaks the > > *at-least-once* gaurantee while relaunch of the opeartor or when master > is > > killed and application is restarted. > > > > Solutions: > > - Fix windowId for stateless leaf operators from upstream opeartor. But > it > > has some issues when we have a join with two upstrams operators at > > different windowId. If we set the windowID to min(upstream windowId), > then > > we need to again recalulate the new recovery window ids for upstream > paths > > from this operators. > > > > - Other solution is to create a empty file in checkpoint directory for > > stateless operators. This will help us to identify the checkpoints of > > stateless operators during relaunch instead of computing from latest > > timestamp. > > > > - Bring the entire DAG to committedWindowId. This could be achived using > > writing committedWindowId in a journal. we need to make sure that we are > > not puring the checkpointed state until the committedWundowId is saved in > > journal. > > > > Let me know your thoughs on this and preferred solution. > > > > Regards, > > -Tushar. > > >
