Eugene Koifman created HIVE-18978:
-------------------------------------
Summary: ConditionalTask.addDependentTask(Task t) adds t in the
wrong place
Key: HIVE-18978
URL: https://issues.apache.org/jira/browse/HIVE-18978
Project: Hive
Issue Type: Bug
Components: Query Processor
Reporter: Eugene Koifman
{{ConditionalTask.addDependentTask(Task t) }} is implemented like this:
{noformat}
/**
* Add a dependent task on the current conditional task. The task will not be a
direct child of
* conditional task. Actually it will be added as child task of associated tasks.
*
* @return true if the task got added false if it already existed
*/
@Override
public boolean addDependentTask(Task<? extends Serializable> dependent) {
boolean ret = false;
if (getListTasks() != null) {
ret = true;
for (Task<? extends Serializable> tsk : getListTasks()) {
ret = ret & tsk.addDependentTask(dependent);
}
}
return ret;
}
{noformat}
So let’s say, the tasks in the ConditionalTask are A,B,C, but they have
children.
{noformat}
CondTask
|--A
|--A1
|-A2
|--B
|--B1
|--C
|--C1
{noformat}
The way ConditionalTask.addDependent() is implemented, MyTask becomes a
sibling of A1,
B1 and C1. So even if only 1 branch of ConditionalTask is executed (and
parallel task
execution is enabled), there is no guarantee (as I see) that MyTask runs
after A2 or
B1 or C1, which is really what is needed.
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