Hi, I am trying to understand how a runner can support the Stateful ParDo. Currently our runner relies on the SimpleDoFnRunner (Beam-0.5.0). But it cannot pass ParDoTest#testValueStateSideOutput ( https://github.com/apache/beam/blob/master/sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/ParDoTest.java#L1607 )
The reason is that it maintains a global state instead of a *per-key* state as explained in the latest Beam blog. I scanned through the implementation of the SimpleDoFnRunner, the implementation does not seem to consider the *per-key* state either ( https://github.com/apache/beam/blob/master/runners/core-java/src/main/java/org/apache/beam/runners/core/SimpleDoFnRunner.java#L626 ). May I ask what is the recommended solution to handle stateful ParDo? Thanks, Shen
