[GitHub] storm pull request: [STORM-468] java.io.NotSerializableException s...

[HeartSaVioR <gi...@git.apache.org>]

Github user HeartSaVioR commented on a diff in the pull request:

    https://github.com/apache/storm/pull/477#discussion_r26999928
  
    --- Diff: docs/documentation/FAQ.md ---
    @@ -62,6 +62,10 @@ You can join streams with join, merge or multiReduce.
     
     At time of writing, you can't emit to multiple output streams from Trident -- see [STORM-68](https://issues.apache.org/jira/browse/STORM-68)
     
    +### Why am I getting a NotSerializableException/IllegalStateException when my topology is being started up?
    +
    +Within the Storm lifecycle, the topology is instantiated and then serialized to byte format to be stored in ZooKeeper, prior to the topology being executed. Within this step, if a spout or bolt within the topology has an initialized unserializable property, serialization will fail. If there is a need for a field that is unserializable, initialize it within the bolt or spout's prepare method, which is run after the topology is delivered to the worker.
    --- End diff --
    
    I'm not sure but it may be better to document "serialized fields' values are reused when workers are relaunched whether live worker modifies it or not.". 
    I had this issue earlier, and sure it was by mistake, but it would be hard to find bug.
    
    Wish to hear everyone's thought.


---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastructure@apache.org or file a JIRA ticket
with INFRA.
---