OptaPlanner: Gaps in Chained Through Time Pattern
I'm just starting learning to use OptaPlanner recently. Please pardon me if there is any technically inaccurate description below.
Basically, I have a problem to assign several tasks on a bunch of machines. Tasks have some precedence restrictions such that some task cannot be started before the end of another task. In addition, each task can only be run on certain machines. The target is to minimize the makespan of all these tasks.
I modeled this problem with Chained Through Time Pattern in which each machine is the anchor. But the problem is that tasks on certain machine might not be executed sequentially due to the precedence restriction. For example, Task B can only be started after Task A completes while Tasks A and B are executed on machines I and II respectively. This means during the execution of Task A on machine I, if there is no other task that can be run on machine II, then machine II can only keep idle until Task A completes at which point Task B could be started on it. This kind of gap is not deterministic as it depends on the duration of Task A with respect to this example. According to the tutorial of OptaPlanner, it seems that additional planning variable gaps should be introduced for this kind of problem. But I have difficulty in modeling this gap variable now. In general, how to integrate the gap variable in the model using Chained Through Time Pattern? Some detailed explanation or even a simple example would be highly appreciated.
Moreover, I'm actually not sure whether chained through time pattern is suitable for modeling this kind of task assigning problem or I just used an entirely inappropriate method. Could someone please shed some light on this? Thanks in advance.
optaplanner
asked Nov 16 '18 at 1:20
gerrykengerryken
13
add a comment |
I'm just starting learning to use OptaPlanner recently. Please pardon me if there is any technically inaccurate description below.
Basically, I have a problem to assign several tasks on a bunch of machines. Tasks have some precedence restrictions such that some task cannot be started before the end of another task. In addition, each task can only be run on certain machines. The target is to minimize the makespan of all these tasks.
I modeled this problem with Chained Through Time Pattern in which each machine is the anchor. But the problem is that tasks on certain machine might not be executed sequentially due to the precedence restriction. For example, Task B can only be started after Task A completes while Tasks A and B are executed on machines I and II respectively. This means during the execution of Task A on machine I, if there is no other task that can be run on machine II, then machine II can only keep idle until Task A completes at which point Task B could be started on it. This kind of gap is not deterministic as it depends on the duration of Task A with respect to this example. According to the tutorial of OptaPlanner, it seems that additional planning variable gaps should be introduced for this kind of problem. But I have difficulty in modeling this gap variable now. In general, how to integrate the gap variable in the model using Chained Through Time Pattern? Some detailed explanation or even a simple example would be highly appreciated.
Moreover, I'm actually not sure whether chained through time pattern is suitable for modeling this kind of task assigning problem or I just used an entirely inappropriate method. Could someone please shed some light on this? Thanks in advance.
optaplanner
asked Nov 16 '18 at 1:20
gerrykengerryken
13
I think the timeslot pattern would be a better fit, as you can write rules that enforce that certain tasks can't be in the same timeslot. But then your tasks must have the same length (which I guess they don't). Or maybe even better, use the time grain pattern with a fine time granularity (though this could be slower, as stated in the docs). Chained through time would be quite difficult I think.
– n1ck
Nov 16 '18 at 13:58
add a comment |
I'm just starting learning to use OptaPlanner recently. Please pardon me if there is any technically inaccurate description below.
Basically, I have a problem to assign several tasks on a bunch of machines. Tasks have some precedence restrictions such that some task cannot be started before the end of another task. In addition, each task can only be run on certain machines. The target is to minimize the makespan of all these tasks.
I modeled this problem with Chained Through Time Pattern in which each machine is the anchor. But the problem is that tasks on certain machine might not be executed sequentially due to the precedence restriction. For example, Task B can only be started after Task A completes while Tasks A and B are executed on machines I and II respectively. This means during the execution of Task A on machine I, if there is no other task that can be run on machine II, then machine II can only keep idle until Task A completes at which point Task B could be started on it. This kind of gap is not deterministic as it depends on the duration of Task A with respect to this example. According to the tutorial of OptaPlanner, it seems that additional planning variable gaps should be introduced for this kind of problem. But I have difficulty in modeling this gap variable now. In general, how to integrate the gap variable in the model using Chained Through Time Pattern? Some detailed explanation or even a simple example would be highly appreciated.
Moreover, I'm actually not sure whether chained through time pattern is suitable for modeling this kind of task assigning problem or I just used an entirely inappropriate method. Could someone please shed some light on this? Thanks in advance.
optaplanner
asked Nov 16 '18 at 1:20
gerrykengerryken
13
I'm just starting learning to use OptaPlanner recently. Please pardon me if there is any technically inaccurate description below.
Basically, I have a problem to assign several tasks on a bunch of machines. Tasks have some precedence restrictions such that some task cannot be started before the end of another task. In addition, each task can only be run on certain machines. The target is to minimize the makespan of all these tasks.
I modeled this problem with Chained Through Time Pattern in which each machine is the anchor. But the problem is that tasks on certain machine might not be executed sequentially due to the precedence restriction. For example, Task B can only be started after Task A completes while Tasks A and B are executed on machines I and II respectively. This means during the execution of Task A on machine I, if there is no other task that can be run on machine II, then machine II can only keep idle until Task A completes at which point Task B could be started on it. This kind of gap is not deterministic as it depends on the duration of Task A with respect to this example. According to the tutorial of OptaPlanner, it seems that additional planning variable gaps should be introduced for this kind of problem. But I have difficulty in modeling this gap variable now. In general, how to integrate the gap variable in the model using Chained Through Time Pattern? Some detailed explanation or even a simple example would be highly appreciated.
Moreover, I'm actually not sure whether chained through time pattern is suitable for modeling this kind of task assigning problem or I just used an entirely inappropriate method. Could someone please shed some light on this? Thanks in advance.
optaplanner
optaplanner
asked Nov 16 '18 at 1:20
gerrykengerryken
13
asked Nov 16 '18 at 1:20
gerrykengerryken
13
asked Nov 16 '18 at 1:20
gerrykengerryken
13
asked Nov 16 '18 at 1:20
gerrykengerryken
13
asked Nov 16 '18 at 1:20
gerrykengerryken
13
13
I think the timeslot pattern would be a better fit, as you can write rules that enforce that certain tasks can't be in the same timeslot. But then your tasks must have the same length (which I guess they don't). Or maybe even better, use the time grain pattern with a fine time granularity (though this could be slower, as stated in the docs). Chained through time would be quite difficult I think.
– n1ck
Nov 16 '18 at 13:58
add a comment |
I think the timeslot pattern would be a better fit, as you can write rules that enforce that certain tasks can't be in the same timeslot. But then your tasks must have the same length (which I guess they don't). Or maybe even better, use the time grain pattern with a fine time granularity (though this could be slower, as stated in the docs). Chained through time would be quite difficult I think.
– n1ck
Nov 16 '18 at 13:58
I think the timeslot pattern would be a better fit, as you can write rules that enforce that certain tasks can't be in the same timeslot. But then your tasks must have the same length (which I guess they don't). Or maybe even better, use the time grain pattern with a fine time granularity (though this could be slower, as stated in the docs). Chained through time would be quite difficult I think.
– n1ck
Nov 16 '18 at 13:58
I think the timeslot pattern would be a better fit, as you can write rules that enforce that certain tasks can't be in the same timeslot. But then your tasks must have the same length (which I guess they don't). Or maybe even better, use the time grain pattern with a fine time granularity (though this could be slower, as stated in the docs). Chained through time would be quite difficult I think.
– n1ck
Nov 16 '18 at 13:58
add a comment |
1 Answer
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I'am using chained through time pattern to solve the same question as yours.And to solve the precedence restriction you can write drools rules.
answered Dec 20 '18 at 14:30
李其武李其武
1
add a comment |
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I'am using chained through time pattern to solve the same question as yours.And to solve the precedence restriction you can write drools rules.
answered Dec 20 '18 at 14:30
李其武李其武
1
add a comment |
I'am using chained through time pattern to solve the same question as yours.And to solve the precedence restriction you can write drools rules.
answered Dec 20 '18 at 14:30
李其武李其武
1
add a comment |
I'am using chained through time pattern to solve the same question as yours.And to solve the precedence restriction you can write drools rules.
answered Dec 20 '18 at 14:30
李其武李其武
1
I'am using chained through time pattern to solve the same question as yours.And to solve the precedence restriction you can write drools rules.
answered Dec 20 '18 at 14:30
李其武李其武
1
answered Dec 20 '18 at 14:30
李其武李其武
1
answered Dec 20 '18 at 14:30
李其武李其武
1
answered Dec 20 '18 at 14:30
李其武李其武
1
1
add a comment |
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I think the timeslot pattern would be a better fit, as you can write rules that enforce that certain tasks can't be in the same timeslot. But then your tasks must have the same length (which I guess they don't). Or maybe even better, use the time grain pattern with a fine time granularity (though this could be slower, as stated in the docs). Chained through time would be quite difficult I think.
– n1ck
Nov 16 '18 at 13:58