Add a paragraph on recommended values on running Placement in production on K8s

[elena-kolevska]

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Description

Adds a paragraph on recommended values on running Placement in production on K8s

Issue reference

[alicejgibbons]

minor changes, @msfussell can you review now?

[alicejgibbons]

Suggested change

	The [Placement service]({{< ref "placement.md" >}}) is a critical component in Dapr, responsible for actor placement table dissemination. It's recommended to configure the Placement service with the following values:
	The [placement service]({{< ref "placement.md" >}}) is a critical component in Dapr when using the Actors API and is responsible for actor placement table dissemination. Placement tables are disseminated every time a new actor instance created and thus served by a new pod, or when pod membership of an existing actor instance changes. Details on this process found [here](https://docs.dapr.io/developing-applications/building-blocks/actors/actors-features-concepts/#actor-placement-service).
	When running in production, it's recommended to configure the placement service with the following values:

[alicejgibbons]

@elena-kolevska I added one sentence describing what the placement dissemination is, plz correct it if needed and add a link to the doc: https://docs.dapr.io/developing-applications/building-blocks/actors/actors-features-concepts/#actor-placement-service

[msfussell]

Feedback

1. We should remove the word "critical" which does not add anything to this sentence.
2. I do not understand the need for this section in the sentence "and thus served by a new pod, or when pod membership of an existing actor instance changes" - what do mean by pod membership? This should simply be that when an actor is updated or a new instance added, this information is replicated to other placement service instances, yes?

[alicejgibbons]

Suggested change

	1. **High availability**. Ensure that the Placement service is highly available and can survive individual node failures. Helm chart value: `dapr_placement.ha=true`
	1. **High availability**. Ensure that the placement service is highly available (3 replicas) and can survive individual node failures. Helm chart value: `dapr_placement.ha=true`

[msfussell]

Placement service is a name so it is Placement service rather than placement service.

[alicejgibbons]

Suggested change

	2. **In memory logs**. Use in-memory Raft log store for faster writes. The tradeoff is more disseminations (and thus, network traffic) in an eventual Placement service pod failure. Helm chart value: `dapr_placement.cluster.forceInMemoryLog=true`
	2. **In-memory logs**. Use in-memory Raft log store for faster writes. The tradeoff is more disseminations (and thus, network traffic) and an eventual placement service pod failure. Helm chart value: `dapr_placement.cluster.forceInMemoryLog=true`

[alicejgibbons]

Suggested change

	4. **Timeouts** Control the sensitivity of network connectivity between the Placement service and the sidecars using the below timeout values. You can adjust these values based on your network conditions as needed.
	4. **Timeouts** Control the sensitivity of network connectivity between the placement service and Dapr sidecars using the below timeout values. Smart default values are set but you can adjust these based on your network conditions.

[alicejgibbons]

Suggested change

1. `dapr_placement.keepAliveTime` sets the interval at which the Placement service sends [keep alive](https://grpc.io/docs/guides/keepalive/) pings to daprd on the gRPC stream to check if the connection is still alive. Lower values will lead to shorter actor rebalancing time in case of pod loss/restart, but higher network traffic during normal operation. Accepts values between `1s` and `10s`. Default is `2s`.

1. `dapr_placement.keepAliveTime` sets the interval at which the placement service sends [keep alive](https://grpc.io/docs/guides/keepalive/) pings to Dapr sidecars via gRPC stream to check if the connection is still alive. Lower values will lead to shorter actor rebalancing time in case of pod loss/restart, but higher network traffic during normal operation. Accepts values between `1s` and `10s`. Default is `2s`.

[alicejgibbons]

Suggested change

2. `dapr_placement.keepAliveTimeout` sets the timeout period for daprd to respond to the Placement service's [keep alive](https://grpc.io/docs/guides/keepalive/) pings before the Placement service closes the connection. Lower values will lead to shorter actor rebalancing time in case of pod loss/restart, but higher network traffic during normal operation. Accepts values between `1s` and `10s`. Default is `3s`.

2. `dapr_placement.keepAliveTimeout` sets the timeout period for Dapr sidecars to respond to the placement service's [keep alive](https://grpc.io/docs/guides/keepalive/) pings before closing the connection. Lower values will lead to shorter actor rebalancing time in case of pod loss/restart, but higher network traffic during normal operation. Accepts values between `1s` and `10s`. Default is `3s`.

[alicejgibbons]

Suggested change

3. `dapr_placement.disseminateTimeout` sets the timeout period for dissemination to be delayed after actor membership change (usually related to pod restarts) so as to avoid excessive dissemination during multiple pod restarts. Higher values will reduce the frequency of dissemination, but delay the table dissemination. Accepts values between `1s` and `5s`. Default is `2s`.

3. `dapr_placement.disseminateTimeout` sets the timeout period for dissemination to be delayed after actor pod membership change (usually related to pod restarts) so as to avoid excessive dissemination during multiple pod restarts. Higher values will reduce the frequency of dissemination, but delay the table dissemination which can lead to actor timeouts. Accepts values between `1s` and `5s`. Default is `2s`.

[msfussell]

Suggested change

	The [Placement service]({{< ref "placement.md" >}}) is a critical component in Dapr, responsible for actor placement table dissemination. It's recommended to configure the Placement service with the following values:
	The [Placement service]({{< ref "placement.md" >}}) is responsible for actor placement table dissemination when using the actors API. It's recommended to configure the Placement service with the following values:

[msfussell]

Comments

[msfussell]

Feedback

1. We should remove the word "critical" which does not add anything to this sentence.
2. I do not understand the need for this section in the sentence "and thus served by a new pod, or when pod membership of an existing actor instance changes" - what do mean by pod membership? This should simply be that when an actor is updated or a new instance added, this information is replicated to other placement service instances, yes?

[msfussell]

Placement service is a name so it is Placement service rather than placement service.

[elena-kolevska]

Thanks for the review @msfussell and @alicejgibbons , I addressed your comments in the latest commit.