[TAJO-275] Separating QueryMaster and TaskRunner roles in worker

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.8.0
• Assignee: Keuntae Park
• Reporter: Keuntae Park
• Created: 22/Oct/13 02:29
• Updated: 21/Nov/13 06:51
• Resolved: 21/Nov/13 06:51

Description

In C++ implementation of Tajo worker,
I think it is better to maintain Java code of QueryMaster and implement only TaskRunner as C++ code, rather than implementing both QueryMaster and TaskRunner as C++ code.

Accordingly, standby mode worker will have following 3 modes:
1) TaskRunner + QueryMaster (current implementation)
2) TaskRunner only (C++)
3) QueryMaster only (java)
And, most workers work as C++ TaskRunner, and 1 or 2 workers work as separate QueryMasters (java process).
For backward compatibility, default mode should be mode 1 (TaskRunner + QueryMaster)

To achieve the goal, it needs to separate java TaskRunner and java QueryMaster Worker first.
(And then, implement C++ TaskRunner)