project job scheduling: Multiple job parallel problems - optaplanner

Question

In the same project, I don't want two jobs to run in parallel. How should I design it?
Is there a rule in the drl file that does not allow two jobs under the same project to run at the same time?
If there is no such thing, how should two jobs under the same project not run simultaneously?
rule "nonrenewableResourceCapacity"
when
$resource : Resource(renewable == false, $capacity : capacity)
accumulate(
ResourceRequirement(resource == $resource,
$executionMode : executionMode,
$requirement : requirement)
and Allocation(executionMode == $executionMode);
$used : sum($requirement);
$used > $capacity
)
then
scoreHolder.addHardConstraintMatch(kcontext, 0, $capacity - $used);
end
rule "renewableResourceUsedDay"
salience 1 // Do these rules first (optional, for performance)
when
ResourceRequirement(resourceRenewable == true, $executionMode : executionMode, $resource : resource)
Allocation(executionMode == $executionMode,
$startDate : startDate, $endDate : endDate)
then
for (int i = $startDate; i < $endDate; i++) {
insertLogical(new RenewableResourceUsedDay($resource, i));
}
end
rule "renewableResourceCapacity"
when
RenewableResourceUsedDay($resource : resource, $capacity : resourceCapacity, $usedDay : usedDay)
accumulate(
ResourceRequirement(resource == $resource,
$executionMode : executionMode,
$requirement : requirement)
and Allocation(executionMode == $executionMode, $usedDay >= startDate, $usedDay < endDate);
$used : sum($requirement);
$used > $capacity
)
then
scoreHolder.addHardConstraintMatch(kcontext, 0, $capacity - $used);
end
// ############################################################################
// Soft constraints
// ############################################################################
rule "totalProjectDelay"
when
Allocation(jobType == JobType.SINK, endDate != null, $endDate : endDate,
$criticalPathEndDate : projectCriticalPathEndDate)
then
scoreHolder.addSoftConstraintMatch(kcontext, 0, $criticalPathEndDate - $endDate);
end
rule "totalMakespan"
when
accumulate(
Allocation(jobType == JobType.SINK, $endDate : endDate);
$maxProjectEndDate : max($endDate)
)
then
scoreHolder.addSoftConstraintMatch(kcontext, 1, - (Integer) $maxProjectEndDate);
end

Answer 1

In task assignment, when you never want to run 2 jobs in parallel (so its a hard constraint, for all jobs), I'd probably make it a build-in hard constraint and basically model it like TSP.
If it's just pairs of specific jobs that shouldn't run in parallel, I'd have the variable listener detect that the 2 jobs would be run at the same time and delay the start time of the job that can start the latest. If they can both start at the same time, the one with the lowest id starts first and the other is delayed. This last bit is to avoid score corruption with incremental calculation.