Hi Ashwin, This is indeed a very required functionality.
I think this is applicable for all three types of operators: Input (e.g. HDFSInput, JDBCInput, etc), Process (e.g. Enrichment), Output (JDBCOutput, HDFSOutput, etc) I tried to do something similar: https://github.com/chinmaykolhatkar/incubator-apex-malhar/blob/APEXMALHAR-1963_AsyncProcessor/library/src/main/java/com/datatorrent/lib/async/AbstractAsyncProcessor.java But this had limitation related extending another class other than this abstract class etc.... >From what you have mentioned above, I see the functionality basically provides asynchronous processing of tuples. Considering this is a common functionality, Can this feature instead be added in platform (apex-core) itself? Thanks, Chinmay. On Tue, Mar 29, 2016 at 10:20 AM, Mohit Jotwani <[email protected]> wrote: > Dear Ashwin, > > The approach sounds good. I am assuming that this will be done for all the > output data stores and not limited to JDBC. > > +1 > > Regards, > Mohit > > On Tue, Mar 29, 2016 at 5:17 AM, Ashwin Chandra Putta < > [email protected]> wrote: > > > There are many use cases in which we are writing tuples to external > system > > using JDBC etc. There are instances when the external system might be > slow > > and down for some time. In those cases, the current implementation of > jdbc > > output operators fail and restart until the external system is up again. > > Meanwhile, the DAG is slowed down by this operator. To deal with such > > scenarios, we should write the output in a reconciled fashion where the > > reconciler thread is writing at the pace of external system. We should > also > > provide an ability to spool the data to disk when the external system is > > down or the output operators queue is full. > > > > Here are the proposed features for the output operator. > > > > 1. Write to external system in a separate reconciler thread. > > 2. Queue the tuples in memory for reconciler thread to consume. > > 3. Spool the incoming tuples to hdfs using a WAL when the queue is full. > > 4. Read from WAL and write to queue as queue is being consumed. > > 5. When external system is able to consume as fast as incoming > throughput, > > WAL is not written. The queue will just buffer the tuples before writing > to > > external system. > > > > Here is the JIRA: https://issues.apache.org/jira/browse/APEXMALHAR-2037 > > > > Please let me know if you have any feedback on the design. > > > > -- > > > > Regards, > > Ashwin. > > >
