He-Pin opened a new issue, #3362:
URL: https://github.com/apache/pekko/issues/3362
### Summary
`AdjustPoolSize` sent to a `ClusterRouterPool` can create a local routee
without applying the cluster pool's deployment constraints. In particular, it
can create a local child when `allowLocalRoutees` is `false`. The same
inherited path also does not consult `useRoles`, `totalInstances`, or
`maxInstancesPerNode`.
### Reproducer
On current `main` (`1fa250d450e18bbebd0374378b6e2a8069473e46`), this
directional test in `ClusterRouterSupervisorSpec` exposes the issue:
```scala
import pekko.routing.{ AdjustPoolSize, GetRoutees, Routees, RoundRobinPool }
"not create a local routee through AdjustPoolSize when local routees are
disabled" in {
val router = system.actorOf(
ClusterRouterPool(
RoundRobinPool(nrOfInstances = 0),
ClusterRouterPoolSettings(
totalInstances = 1,
maxInstancesPerNode = 1,
allowLocalRoutees = false))
.props(Props(classOf[KillableActor])))
router ! AdjustPoolSize(1)
router ! GetRoutees
expectMsg(Routees(Vector.empty))
}
```
Run with JDK 17:
```text
sbt "cluster / Test / testOnly
org.apache.pekko.cluster.routing.ClusterRouterSupervisorSpec"
```
The assertion fails because a local routee named `c1` is present:
```text
expected Routees(Vector()), found
Routees(Vector(ActorRefRoutee(Actor[pekko://.../c1])))
```
### Cause
`ClusterRouterPoolActor` inherits `RouterPoolActor` and delegates unmatched
messages, including `AdjustPoolSize`, to `super.receive`:
-
https://github.com/apache/pekko/blob/1fa250d450e18bbebd0374378b6e2a8069473e46/cluster/src/main/scala/org/apache/pekko/cluster/routing/ClusterRouterConfig.scala#L403-L409
The inherited handler calls `pool.newRoutee` directly for each requested
addition:
-
https://github.com/apache/pekko/blob/1fa250d450e18bbebd0374378b6e2a8069473e46/actor/src/main/scala/org/apache/pekko/routing/RoutedActorCell.scala#L203-L214
For a `ClusterRouterPool`, `newRoutee` attaches a local child without
checking cluster settings:
-
https://github.com/apache/pekko/blob/1fa250d450e18bbebd0374378b6e2a8069473e46/cluster/src/main/scala/org/apache/pekko/cluster/routing/ClusterRouterConfig.scala#L342-L360
In contrast, the normal cluster-pool allocation path calls
`selectDeploymentTarget`, which applies available-node, total-instance, and
per-node limits:
-
https://github.com/apache/pekko/blob/1fa250d450e18bbebd0374378b6e2a8069473e46/cluster/src/main/scala/org/apache/pekko/cluster/routing/ClusterRouterConfig.scala#L411-L450
The documentation also states that `max-nr-of-instances-per-node` will not
be exceeded:
-
https://github.com/apache/pekko/blob/1fa250d450e18bbebd0374378b6e2a8069473e46/docs/src/main/paradox/cluster-routing.md#L171-L177
### Expected behavior
`AdjustPoolSize` must not create a routee on a node excluded by
`allowLocalRoutees` or `useRoles`, and must not silently bypass cluster pool
limits.
The exact management semantics need a maintainer decision. Possible
approaches include rejecting/ignoring `AdjustPoolSize` for cluster pools, or
interpreting it through the cluster allocation path while preserving
`totalInstances` and `maxInstancesPerNode`.
### Additional context
This was found while investigating #3253. It is separate from the generic
pool/resizer-bounds question there: the generic `AdjustPoolSize` contract is a
direct management override, whereas cluster deployment settings describe node
eligibility and per-node limits.
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