[HIVE-6831] The job schedule in condition task could not be correct with skewed join optimization

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.11.0
• Component/s: Query Processor

Environment

Hive 0.11.0

• Assignee: Unassigned
• Reporter: william zhu
• Created: 03/Apr/14 10:06
• Updated: 08/Apr/14 06:51

Description

Code snippet in ConditionalTask.java as bellow:

// resolved task
if (driverContext.addToRunnable(tsk))

{ console.printInfo(tsk.getId() + " is selected by condition resolver."); }

The selected task is added into the runnable queue immediately without any dependency checking. If the selected task is original task ,and its parent task is not being executed, then the result will be incorrect.

Like this:
1. Before skew join optimization:
Step1 ,Step 2 <-- step 3 ( Step1 and Step2 is Step 3's parent)
2. after skew join optimization:
Step1 <- Step4 (ConditionTask)<- consists of [Step3,Step10]
Step2 <- Step5 (ConditionTask)<- consists of [Step3,Step11]
3. Runing
Step3 is selected in Step4 and Step5
Step3 will be execute immediately after Step4 , its not correct.
Step3 will be execute after Step5 again, its not correct either.
4. The correct scheduler is that step3 will be execute after step4 and step5.
5. So, I add a checking operate in the snippet as bellow:

if (!driverContext.getRunnable().contains(tsk)) {
console.printInfo(tsk.getId() + " is selected by condition resolver.");
if(DriverContext.isLaunchable(tsk))

{ driverContext.addToRunnable(tsk); }

}

So , that is work right for me in my enviroment. I am not sure whether it will has some problems in someother condition.