[UIMA-2162] Fix UIMA AS race condition allowing parent CAS to hit the Flow Controller ahead of its child CASes

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.1AS
• Fix Version/s: 2.4.0AS
• Component/s: Async Scaleout
• Assignee: Jaroslaw Cwiklik
• Reporter: Jaroslaw Cwiklik
• Created: 08/Jul/11 19:41
• Updated: 19/Sep/11 16:37
• Resolved: 19/Sep/11 16:37

Description

A race condition exists in the UIMA AS Aggregate with a scaled up reply queue. Multiple, concurrent threads consuming CASes produced by a Cas Multiplier execute at different speeds (most likely due to different de-serialization times) allowing for a parent CAS to call Flow Controller's next() method before all of its child CASes obtain their Flow objects. Add necessary synchronization to orchestrate orderly flow of CASes to make sure that the parent CAS never reaches the Flow Controller ahead of its children.