/** Creates new DeadlockGraph from plan and checks for cycles */
public boolean hasDeadlock(List<? extends PlanNode> sinks) {
this.g = new DeadlockGraph();
for (PlanNode s : sinks) {
s.accept(this);
}
if (g.hasCycle()) {
return true;
} else {
return false;
}
}
public void resolveDeadlocks(List<? extends PlanNode> sinks) {
for (PlanNode s : sinks) {
s.accept(this);
}
if (g.hasCycle()) {
// in the remaining plan is a cycle
for (DeadlockVertex v : g.vertices) {
// first strategy to fix -> swap build and probe side
if (v.getOriginal().getDriverStrategy().equals(DriverStrategy.HYBRIDHASH_BUILD_FIRST)) {
v.getOriginal().setDriverStrategy(DriverStrategy.HYBRIDHASH_BUILD_SECOND);
if (hasDeadlock(sinks)) {
// Didn't fix anything -> revert
v.getOriginal().setDriverStrategy(DriverStrategy.HYBRIDHASH_BUILD_FIRST);
} else {
// deadlock resolved
break;
}
}
// other direction
if (v.getOriginal().getDriverStrategy().equals(DriverStrategy.HYBRIDHASH_BUILD_SECOND)) {
v.getOriginal().setDriverStrategy(DriverStrategy.HYBRIDHASH_BUILD_FIRST);
if (hasDeadlock(sinks)) {
// Didn't fix anything -> revert
v.getOriginal().setDriverStrategy(DriverStrategy.HYBRIDHASH_BUILD_SECOND);
} else {
// deadlock resolved
break;
}
}
}
// switching build and probe side did not help -> pipeline breaker
for (DeadlockVertex v : g.vertices) {
if (v.getOriginal() instanceof DualInputPlanNode) {
DualInputPlanNode n = (DualInputPlanNode) v.getOriginal();
// what is the pipelined side? (other side should be a dam, otherwise operator could not
// be source of deadlock)
if (!(n.getDriverStrategy().firstDam().equals(DamBehavior.FULL_DAM)
|| n.getInput1().getLocalStrategy().dams()
|| n.getInput1().getTempMode().breaksPipeline())
&& (n.getDriverStrategy().secondDam().equals(DamBehavior.FULL_DAM)
|| n.getInput2().getLocalStrategy().dams()
|| n.getInput2().getTempMode().breaksPipeline())) {
n.getInput1().setTempMode(n.getInput1().getTempMode().makePipelineBreaker());
} else if (!(n.getDriverStrategy().secondDam().equals(DamBehavior.FULL_DAM)
|| n.getInput2().getLocalStrategy().dams()
|| n.getInput2().getTempMode().breaksPipeline())
&& (n.getDriverStrategy().firstDam().equals(DamBehavior.FULL_DAM)
|| n.getInput1().getLocalStrategy().dams()
|| n.getInput1().getTempMode().breaksPipeline())) {
n.getInput2().setTempMode(n.getInput2().getTempMode().makePipelineBreaker());
}
// Deadlock resolved?
if (!hasDeadlock(sinks)) {
break;
}
}
}
}
}
