A recent change made it so that the CPUManager receives a list of
initial containers that exist on the system at startup. This list can be
non-empty, for example, after a kubelet retart.
This commit ensures that the CPUManagers containerMap structure is
initialized with the containers from this list.
This check is redundant since we protect this call with a call to
`m.sourcesReady.AllReady()` earlier on. Moreover, having this check in
place means that we will leave some stale state around in cases where
there are actually no active pods in the system and this loop hasn't
cleaned them up yet. This can happen, for example, if a pod exits while
the kubelet is down for some reason. We see this exact case being
triggered in our e2e tests, where a test has been failing since October
when this change was first introduced.
This change is to prevent problems when we remove the V1->V2 migration
code in the future. Without this, the checksums of all checkpoints would
be hashed with the name CPUManagerCheckpointV2 embedded inside of them,
which is undesirable. We want the checkpoints to be hashed with the name
CPUManagerCheckpoint instead.
The updated CPUManager from PR #84462 implements logic to migrate the
CPUManager checkpoint file from an old format to a new one. To do so, it
defines the following types:
```
type CPUManagerCheckpoint = CPUManagerCheckpointV2
type CPUManagerCheckpointV1 struct { ... }
type CPUManagerCheckpointV2 struct { ... }
```
This replaces the old definition of just:
```
type CPUManagerCheckpoint struct { ... }
```
Code was put in place to ensure proper migration from checkpoints in V1
format to checkpoints in V2 format. However (and this is a big however),
all of the unit tests were performed on V1 checkpoints that were
generated using the type name `CPUManagerCheckpointV1` and not the
original type name of `CPUManagerCheckpoint`. As such, the checksum in
the checkpoint file uses the `CPUManagerCheckpointV1` type to calculate
its checksum and not the original type name of `CPUManagerCheckpoint`.
This causes problems in the real world since all pre-1.18 checkpoint
files will have been generated with the original type name of
`CPUManagerCheckpoint`. When verifying the checksum of the checkpoint
file across an upgrade to 1.18, the checksum is calculated assuming
a type name of `CPUManagerCheckpointV1` (which is incorrect) and the
file is seen to be corrupt.
This patch ensures that all V1 checksums are verified against a type
name of `CPUManagerCheckpoint` instead of ``CPUManagerCheckpointV1`.
It also locks the algorithm used to calculate the checksum in place,
since it wil never change in the future (for pre-1.18 checkpoint
files at least).
These information associatedd with these containers is used to migrate
the CPUManager state from it's old format to its new (i.e. keyed off of
podUID and containerName instead of containerID).
For now, we just pass 'nil' as the set of 'initialContainers' for
migrating from old state semantics to new ones. In a subsequent commit
will we pull this information from higher layers so that we can pass it
down at this stage properly.
Previously, the state was keyed off of containerID intead of podUID and
containerName. Unfortunately, this is no longer possible as we move to a
to model where we we allocate CPUs to containers at pod adit time rather
than container start time.
This patch is the first step towards full migration to the new
semantics. Only the unit tests in cpumanager/state are passing. In
subsequent commits we will update the CPUManager itself to use these new
semantics.
This patch also includes code to do migration from the old checkpoint format
to the new one, assuming the existence of a ContainerMap with the proper
mapping of (containerID)->(podUID, containerName). A subsequent commit
will update code in higher layers to make sure that this ContainerMap is
made available to this state logic.
This ensures that we have the most up-to-date state when generating
topology hints for a container. Without this, it's possible that some
resources will be seen as allocated, when they are actually free.
This will become especially important as we move to a model where
exclusive CPUs are assigned at pod admission time rather than at pod
creation time.
Having this function will allow us to do garbage collection on these
CPUs anytime we are about to allocate CPUs to a new set of containers,
in addition to reclaiming state periodically in the reconcileState()
loop.
- As discussed in reviews and other public channels,
this abstraction is used to represent numa nodes, not sockets.
- There is nothing inherently related to sockets in this package anyway.
As part of this, update the logic to use the NUMA information instead of
the Socket information when generating and consuming TopologyHints in
the CPUManager.
Unfortunately, the NUMA information is not readily available from
cadvisor, so we have to roll the logic to discover it by hand. In the
future, we should remove this custiom code to use the information
provided by cadvisor once it is made available.
