feat(spanner): set manual affinity incase of gRPC-GCP extenstion #3215
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| private static GcpManagedChannelOptions grpcGcpOptionsWithMetrics(SpannerOptions options) { | ||
| GcpManagedChannelOptions grpcGcpOptions = | ||
| MoreObjects.firstNonNull(options.getGrpcGcpOptions(), new GcpManagedChannelOptions()); | ||
| GcpChannelPoolOptions gcpChanelPoolOptions = |
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| GcpChannelPoolOptions gcpChanelPoolOptions = | |
| GcpChannelPoolOptions gcpChannelPoolOptions = |
| .getCallOptions() | ||
| .withOption( | ||
| GcpManagedChannel.AFFINITY_KEY, | ||
| Option.CHANNEL_HINT.getLong(options).toString())); |
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This channel hint can be any random Long, meaning that we might be using a very large range of different channel hints. That again means that we might be adding an unbounded set of channel hints to the map in grpc-gcp. We should add a computation here that makes sure that the set of hints is limited (e.g. do something like hint % options.getNumChannels()).
See
| // Set channel affinity in GAX. This is a no-op for gRPC-GCP. | ||
| context = context.withChannelAffinity(Option.CHANNEL_HINT.getLong(options).intValue()); | ||
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| // Set channel affinity in gRPC-GCP. This is a no-op for GAX. |
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nit: is it possible to only do this if grpc-gcp is being used? I know that it is a no-op for gax, and so does not affect anything in that way, but context.withCallOptions(..) always creates a new CallContext instance. That means that we reserve a small bit of additional memory for every RPC that we invoke that then needs to be cleaned up again afterwards. (And yes, that's a bit of a pre-emptive optimization, so if it is not possible or hard, then please ignore this comment, but if there's a simple if-condition that we can use, then let's do that.)
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I have made changes to do it only when grpcgcp is enabled. Can you please take a look?
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Earlier, gRPC-GCP maintains affinity using the ApiConfig by looking into the gRPC messages to get an affinity key.
This PR sets the affinity manually to gRPC-GCP via call options. Reason - With multiplexed sessions we need to maintain transaction to channel affinity, and with regular sessions we need to maintain session to channel affinity.
Setting manual affinity will override the API config setting.
References: