Yes, Nan, totally agree. To be on the same page, that's exactly what I wrote wasn't it?
On Tue, May 8, 2018 at 11:14 AM Nan Zhu <zhunanmcg...@gmail.com> wrote: > besides that, one of the things which is needed by multiple frameworks is > to schedule tasks in a single wave > > i.e. > > if some frameworks like xgboost/mxnet requires 50 parallel workers, Spark > is desired to provide a capability to ensure that either we run 50 tasks at > once, or we should quit the complete application/job after some timeout > period > > Best, > > Nan > > On Tue, May 8, 2018 at 11:10 AM, Reynold Xin <r...@databricks.com> wrote: > >> I think that's what Xiangrui was referring to. Instead of retrying a >> single task, retry the entire stage, and the entire stage of tasks need to >> be scheduled all at once. >> >> >> On Tue, May 8, 2018 at 8:53 AM Shivaram Venkataraman < >> shiva...@eecs.berkeley.edu> wrote: >> >>> >>>> >>>>> - Fault tolerance and execution model: Spark assumes fine-grained >>>>> task recovery, i.e. if something fails, only that task is rerun. This >>>>> doesn’t match the execution model of distributed ML/DL frameworks that >>>>> are >>>>> typically MPI-based, and rerunning a single task would lead to the >>>>> entire >>>>> system hanging. A whole stage needs to be re-run. >>>>> >>>>> This is not only useful for integrating with 3rd-party frameworks, but >>>> also useful for scaling MLlib algorithms. One of my earliest attempts in >>>> Spark MLlib was to implement All-Reduce primitive (SPARK-1485 >>>> <https://issues.apache.org/jira/browse/SPARK-1485>). But we ended up >>>> with some compromised solutions. With the new execution model, we can set >>>> up a hybrid cluster and do all-reduce properly. >>>> >>>> >>> Is there a particular new execution model you are referring to or do we >>> plan to investigate a new execution model ? For the MPI-like model, we >>> also need gang scheduling (i.e. schedule all tasks at once or none of them) >>> and I dont think we have support for that in the scheduler right now. >>> >>>> >>>>> -- >>>> >>>> Xiangrui Meng >>>> >>>> Software Engineer >>>> >>>> Databricks Inc. [image: http://databricks.com] <http://databricks.com/> >>>> >>> >>> >
