[CRUNCH-90] Object reuse is not accounted for in mapper fusion

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.4.0
• Assignee: Gabriel Reid
• Reporter: Gabriel Reid
• Created: 06/Oct/12 12:42
• Updated: 16/Nov/12 20:06
• Resolved: 08/Oct/12 15:15

Description

When multiple DoFns are run over the same output (i.e. in the case of mapper fusion), the same value object is passed to multiple underlying DoFns. If the state of that value object is changed by one DoFn, other DoFns are called with the updated object.

This is a situation that can happen quite easily when the input of a DoFn is simply updated and then emitted. In general, this bug will only affect values whose type is the same as the underlying serialization type.