I'm doing a simulation of an industry in Anylogic. It consists of three equal production lines, they all have the same number of processes (in the case services) and each service has a Resource attached (aka. a Machine). The products that are produced in the three lines will only be joined together in the end (at the final stock before delivery).
However, my last process of each line can have an increase or decrease in resources (machines) when needed. For example, line 1 had a machine failure and stopped for some time and now instead of needing 4 machines to complete the order it will need 6.
In addition, if one of this machines placed in this process breaks (because of a failure), I need the service to keep working but with less resources. So, for example, I have 4 machines in the last process of line 1, one of these machines had a break down, I would like the other 3 to keep producing.
Which possible solution can be used for this? I tried to simulate this in the service itself but it doesn't work with less resources then specified.
From what I understood I think you need to model the three lines separately and use three different resourcePools for your machines. Doing this you will have control over the resource capacity on every line and can change them based on any events. If your question is about how to change capacity of one line when another line fails, I suggest using the "send to flowchart" option in resource failure and you can use flowchart blocks to change capacities and execute any other code necessary.
If your 3 lines are identical, you can create a custom flowchart block and pass the resourcePool as a parameter to the custom block.This way you don't have to replicate your logic three times.
Related
I know the basics of AnyLogic/Process Modeling Library and am about to teach simulation of basic queues with AnyLogic, transitioning from Simul8 that I 've used for many years.
I have agents of two types, 1 and 2, sent to respective queues 1 and 2, which then feed a single "service" point, so that type 1 takes higher priority (that is, whenever service is ready to pull work, it pulls from queue 1 if it is non-empty, regardless of the size of queue 2). How to capture this as simply as possible?
Having seen the reference pages for a Queue object, my preliminary (unworked) idea is to use a single queue, and control agent priority by the Queue.QUEUING_PRIORITY- Priority-based" option.
For comparison, a solution in the Simul8 software is: set "service" routing-in discipline to "priority"; and assign different priorities to the two queues.
Yes you are right you cant use two queues as the pull from the queues will be done in a round robin fashion. See the screenshot below from the AnyLogic training textbook
You should use queueing in a single queue and you can have either a single parameterised source or two.
See example below
I have 2 sources and at each of them, I set the priority to a local variable inside my agent. Agents from source 1's variable is set to 1 and the from source set to 0.
Then inside the queue, I set the priority so that the agents from source 1 is always in front.
I am building a simulation model for a production line. There are two shifts (morning and night shift, 12 hours each) daily. Within each shift, the workers are split into 4 groups and each group goes for meal breaks at a staggered timing (eg. 4 workers in morning shift, first worker goes for break at 9am, second goes at 10am, etc.). These workers will also take ad-hoc breaks at random occurrences during their shift.
Not sure which method would work:
Creating an individual schedule within the agent and let it change states according to the schedule?
Use a common schedule for the entire resource pool, but will it be possible to pick which agent goes for break at the break time? Or will the agent be picked at random? Caus my concern is that i'll need the agents to take breaks but at staggered intervals.
Or should I generate this in a different approach?
Good question!
On option 2)
If you use the resource pool you will not be able to choose a specific agent as shifts and breaks are created for the entire pool.
What you can do is to define the capacity of the resource pool using, multiple schedules
This can help you artificially define the staggered. nature of the break-taking for resources.
Refer to the help for more details - https://anylogic.help/library-reference-guides/process-modeling-library/resourcepool.html
I believe this answers your question already but here are my notes on the other option.
Option 1)
If you require more advanced flexibility and control over the breaks and you do have the required Java skills (and time!) you can create custom code that controls when to send agents on a break and when to to return. You can use StateCharts inside your agents to build this logic. But then this will not be compatible with the resource pool since the resource pool will be oblivious to the state of the agents inside the pool and it will seize units that are taking a break...
So in this case your size delay and release will also be custom.
This is a lot of work and should only be attempted if you have the time, skills and require a level of flexibility and customization not offered by the resource pool.
I have a resource pool and a service block. The number of the operator in the resource pool is 5 which is linked to the service block. I would like to setup the service in a way that the more workers work on the service the delay time decreases. (ex: if 1 worker works the delay time is 10 min - if 2 workers work the delay time is 5 min. - if 3 workers work the delay time is 3.33 min). I would like up to 5 operators to be working at the same time in the service block based on their availability.
Service Block and Resource Pool
How can I achieve this?
So you're trying to do two things with your Service block:
Seize a dynamic number of units (in the simplest case, seize all available units).
Have the delay time dependent on the number of units seized (in the simplest case, just decreasing multiplicatively according to the number of resources).
For the former, assuming you're seizing from a single pool, just enter a dynamic expression in the "Number of units" property. In the simplest case (seize all available) it would just be pool.idle() (for a resource pool called pool) but that's problematic if the next agent arrives whilst the first is being processed (because it will be treated as needing zero resources) so, depending what you want, you might need to do something like put RestrictedAreaStart / End blocks around your Service block so only one agent can be in the Service block at once.
NB: AnyLogic currently has a bug/limitation that the resource pool's idle/busy counts (from its idle() and busy() functions) are not guaranteed to be correct unless you are at a later simulation time than when seizes/releases occurred. (This is due to how things are resolved in hidden events under-the-covers.) So, if you want to use them in your determination of the number of resources to seize you need to work round this; e.g., by
tracking the number of busy/idle units via your own counts;
using the isIdle() function on individual resources in the pool instead (which typically requires ensuring the resource pool agents are in a custom population, not the hidden default one, so you can explicitly reference/loop through them);
something horrible and hacky like adding a very-small-timeout Delay block before entering a Service block (possibly within RestrictedAreaStart / Ends to ensure that agents don't make it into the Delay, and hence the Service block's seize mechanism, until you want them to).
In general, it makes sense to put the resources-needed calculation in a function (which returns an int and takes the agent as an argument) which you call in the "Number of units" expression. That way you can make the calculation as complex as you like; it would seem you might need a more complex consideration than just "grab everyone" (e.g., perhaps depending on the stream of to-arrive agents if you have knowledge of them, etc.). Maybe, for example, you'd also want to hold your arriving agents in a Wait block beforehand and only release them when the number of resources you want are available. (You'd need to give more precise detail about your requirements to be any more definite here.)
For the variable delay time, have an appropriate dynamic expression for the delay time; you can use the resourceUnits() function to get a list of the resource units seized by your agent. So, in the simplest case (decreases multiplicatively according to the number of resources) it would be something like 10.0 / agent.resourceUnits().size() (for a base delay of 10 time units).
Is there a way to have parallel services and/or delays to occur per agent and move on with the activity that takes the longest. For example if I have an agent that can be painted and serviced at the same time, each requiring a different resource pool with different processing times but the agent will move forward when the process that took the longest is over.
Use a Split block to split your agent into two for the two parallel tasks (Service blocks) and then use a Combine to combine them back again afterwards (with the Combine block outputting the original agent 1).
You can also use RestrictedAreaStart and RestrictedAreaEnd blocks (capacity 1) around the split/combine area to ensure that other agents can't 'jump in' whilst the longest parallel process is still running (but the shorter one has already finished).
Something like the below (with resource pools).
Probably easiest to dynamically setup delay duration and resources needed from within 1 Service element:
calculate the duration your agent will use in each case (painting = 5 mins, servicing = 10 mins) --> use the longer value as the service delay
Also, make the agent require 1 painter and 1 service-engineer as resources.
Only drawback: Your painter will stay for 10 mins as well.
Alternative approach would likely involve creating your own, purely agent-based setup with seizing& releasing
I'm building a solution where we'll have a (service-fabric) stateless service deployed to K instances. This service is tasked with some workload (like querying) and I want to split the workload between them as evenly as I can - and I want to make this a dynamic solution, which means if I decide to go from K instances to N instances tomorrow, I want the workload splitting to happen in a way that it will automatically distribute the load across N instances now. I don't have any partitions specified for this service.
As an example -
Let's say I'd like to query a database to retrieve a particular chunk of the records. I have 5 nodes. I want these 5 nodes to retrieve different 1/5th of the set of records. This can be achieved through some query logic like (row_id % N == K) where N is the total number of instances and K is the unique instance_number.
I was hoping to leverage FabricRuntime.GetNodeContext().NodeId - but this returns a guid which is not overly useful.
I'm looking for a way where I can deterministically say it's instance number M out of N (I need to be able to name the instances through 1..N) - so I can set my querying logic according to this. One of the requirements is if that instance goes down / crashes etc... when SF automatically restarts it, it should still identify as the same instance id - so that 2 or more nodes doesn't query the same set of results.
What is the best of solving this problem? Is there a solution which involves pure configuration through ApplicationManifest.xml or ServiceManifest.xml?
There is no out of the box solution for your problem, but it can be easily done in many different ways.
The simplest way is using the Queue-Based Load Leveling pattern in conjunction with Competing Consumers pattern.
It consists of creating a queue, add the work to the queue, and each instance get one message to process this work, if one instance goes down and the message is not processed, it goes back to the queue and another instance pick it up.
This way you don't have to worry about the number of instances running, failures and so on.
Regarding the work being put in the queue, it will depend if you want to to do batch processing or process item by item.
Item by item, you put one message in the queue for each item being processed, this is a simple way to handle the work and each instance process one message at time, or multiple messages in parallel.
In batch, you can put a message that represents a list of items to be processed and each instance process that batch until completed, this is a bit trickier because you might have to handle the progress of the work being done, in case of failure, the next time you can continue from where it stopped.
The queue approach is a reactive design, in this case the work need to be put in the queue to trigger the processing, If you want a proactive approach and need to keep track of which work goes to who, you probably might be better of using some other approach, like a Leasing mechanism, where each instance acquire a lease that belongs to the instance until it releases the lease, this would more suitable when you work with partitioned data or other mechanism where you can easily split the load.
Regarding the issue with the ID, an option would be the InstanceId of the replica you are on, you can reach by StatelessService.Context.InstanceId, it is not a sequential ID, but it is a random number. It is better than using the node id, because you might have multiple partitions on same node and the id would conflict with each other.
If you decide to use named partitions, you could use order in the partition name instead, so each partition would have a sequential name.
Worth mention that service fabric has a limitation that doesn't allow services to have multiple replicas on same node, because of this limitation you might have to design your services with this in mind, otherwise you won't be able to scale out once the limit is reached. Also, the same thread has some discussion about approaches to process multiple distributed items that might give you some ideas.