Question regarding how PowerDatacenter deallocation works.

[lFirsl]

Hi.

So, as I'm still playing around with the Power suite (PowerHost, PowerDatacentre, PowerVM, etc) to get energy usage estimates, I've come across an issue - which I'm unsure whether is a bug or if I'm misusing the feature set, thus why I'm putting this in a Q&A instead of a issue.

The Problem

While using PowerDatacenter, PowerHosts and PowerVMs, I've noticed that ALL of my PowerVMs got deallocated by the PowerDatacenter despite them having cloudlets submitted to them that are yet to be finished.

Having investigated PowerDatacenter, I found this piece of code:

cloudsim/modules/cloudsim/src/main/java/org/cloudbus/cloudsim/power/PowerDatacenter.java

Lines 234 to 241 in 9a414ff

	/** Remove completed VMs **/
	for (PowerHost host : this.<PowerHost> getHostList()) {
	for (GuestEntity vm : host.getCompletedVms()) {
	getVmAllocationPolicy().deallocateHostForGuest(vm);
	getVmList().remove(vm);
	Log.println("VM #" + vm.getId() + " has been deallocated from host #" + host.getId());
	}
	}

I've pinpointed the issue to be with this line:

cloudsim/modules/cloudsim/src/main/java/org/cloudbus/cloudsim/power/PowerDatacenter.java

Line 236 in 9a414ff

for (GuestEntity vm : host.getCompletedVms()) {

Which has this definition:

cloudsim/modules/cloudsim/src/main/java/org/cloudbus/cloudsim/HostDynamicWorkload.java

Lines 140 to 160 in 9a414ff

	public List<GuestEntity> getCompletedVms() {
	List<GuestEntity> vmsToRemove = new ArrayList<>();
	for (GuestEntity guest : getGuestList()) {
	if (guest.isInMigration()) {
	continue;
	}
	// If vm is in waiting state then don't kill it yet !!!!!!!!!
	if (guest instanceof VirtualEntity vm && vm.isInWaiting()) {
	continue;
	}
	if (guest.getCurrentRequestedTotalMips() == 0) {
	vmsToRemove.add(guest);
	}
	if (guest instanceof VirtualEntity vm && vm.getNumberOfGuests()==0) {
	vmsToRemove.add(vm);
	}
	}
	return vmsToRemove;
	}

My PowerVMs within the PowerHosts seem to fall into this if statement:

cloudsim/modules/cloudsim/src/main/java/org/cloudbus/cloudsim/HostDynamicWorkload.java

Lines 155 to 157 in 9a414ff

	if (guest instanceof VirtualEntity vm && vm.getNumberOfGuests()==0) {
	vmsToRemove.add(vm);
	}

That is to say, the PowerVMs are counted as having "no guests". To my understanding, GuestEntities are primarily VMs and Containers - not cloudlets.

Out of curiosity, I've tried using just PowerContainers without using PowerVMs (so the containers got allocated to PowerHosts directly). This seems to cause the opposite problem - no Container got deallocated despite having no cloudlets to work on - as the PowerDatacentre only ever checks for completed VMs, not containers.

Just to make it clear here, my understanding is that a (Power)VM or (Power)Container should only be deallocated once it runs out of CLOUDLETS to work on, which is not what seems to be happening here.

The Questions

Given the above, I'm wondering the following

1. Am I misunderstanding things, and are the Power classes meant to be used like PowerDatacenter -> PowerHost -> PowerVM -> PowerContainer -> Cloudlet? That is to say, am I always meant to use PowerContainers within PowerVMs? If so, how are PowerContainers checked to be "done" if not via cloudlet completion?
2. If not the above, why would my PowerVMs be deallocated while they still have cloudlets assigned to them? Is this a bug or am I missing something here?

Thank you for taking the time to answer my question! If this turns out to be a bug and not a misuse on my part, I am more than happy to open up another issue so we can keep track of it!

cc: @deRemo

[zijie1024]

@lFirsl I've encountered a similar issue #219 . Have you figured out the correct way to use the power package?