[Bug] moneybatcher sample race condition?

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
java
Domain
distributed-systems

Research direction

Start with the moneybatch sample under core/src/main/java/io/temporal/samples/moneybatch and run TransferWorkflowTest from the linked reproduction branch. Inspect the Workflow.await condition and the test setup for requests exceeding one batch size. Done means the reproduced workflow completes and processes the expected batches instead of remaining blocked.

Written by the indexing model from the issue text.

Description

bug
What are you really trying to do?

I am trying to learn how to do batching using temporal. I found the moneybatch sample and I wanted to make sure that it can handle requests in parallel.

To simulate the behavior, I changed the workflow to withdraw more times than a single batch size as well as added a delay during the deposit call.
What this lead to is that the workflow would continue to run and not complete, it won't even process a single batch.

Describe the bug

This is related to the condition in the workflow:
Workflow.await(() -> count == batchSize);

If count suddenly goes from 0 to a value greater than batchSize, the workflow will continue to run and not complete.

I am new to temporal, so I am not quite sure how to fix this. Is this a bug in the sample or am I doing something wrong?

Image Image
Minimal Reproduction

Download this branch:
https://github.com/derwasp/samples-java/tree/derwasp/moneybatcher

Either run ./run-moneybatch-demo.sh and observe the logs.
Or run the test TransferWorkflowTest and see the failure.

Environment/Versions
  • OS and processor: M4 Mac
  • Temporal Version: (CLI version 1.4.1)
  • Are you using Docker or Kubernetes or building Temporal from source? Docker
Additional context
Dominant language
Java
Stars
258
Forks
189
Avg merge
6d 4h
Merged PRs (30d)
4

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