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Node connection pool
- Distributes requests between fixed number of nodes
- Wraps
The distribution between nodes in connection pool is based on priority and weight parameters from NodeParam struct. The distribution model is presented below. On this scheme nodes with the same priority have the same color.
Priority
Pool component forwards request to the nodes with the highest priority (the lower the value -
the higher the priority). The node 1 from the image's scenario (I) is healthy
and has the highest priority (1), that's why the pool forwards requests from it. There are no other
nodes with priority 1, so node 1 receives all requests. In the second scenario (II) node 1
becomes unhealthy. In that case pool tries to connect nodes with next in priority nodes e.g.
Node 4 and node 2. If all of them become unhealthy too, the pool sends requests to nodes with
priority 3 in scenario (III) and so on.
Weights
If there are several nodes with the same priority, then requests are distributed randomly between
these nodes based on their weights. To do that the proportion of weights is calculated.
For example, for node 2 and node 4 with weights 2 and 8 the distribution would be 20 and 80 percent
respectively.