akka/akka-core

Serialization issues with Option

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#29,923 opened on Dec 30, 2020

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 (3 comments) (0 reactions) (0 assignees)Scala (3,547 forks)batch import
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Description

Some example projects and also the current style guide recommend using Option for state in event sourced behaviors (entities). This causes two issues:

  1. Double serialization - Option is caught by MiscMessageSerializer, which delegates payload serialization to another serializer based on configuration and then serializes the result again with ContainerFormats.Option.
  2. Payload serialization is always synchronous, so this results in blocking IO in a case where state uses AsyncSerializer.

These issues could be fixed by implementing following changes:

  1. Altering documentation to suggest using sealed trait hierarchies or case classes which contain Option to express empty state.
  2. Converting MiscMessageSerializer to AsyncSerializer.

Behavior seems obviously undesirable, so I'm wondering if I am missing something or does this actually need fixing?

I've noticed this issue with Lagom 1.6.4 entities, but since they fallback to Akka actors for everything I assume this is a general Akka issue.

Contributor guide

Research direction
Investigate MiscMessageSerializer to understand how it handles Option types, especially double serialization and synchronous blocking. Review the serialization configuration and how AsyncSerializer is used.
Tech stack
scala
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
ScalaAkkaSerialization
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40