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73 lines
2.4 KiB
73 lines
2.4 KiB
package pub_balancer
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import (
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"github.com/seaweedfs/seaweedfs/weed/mq/topic"
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"google.golang.org/grpc"
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)
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/*
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* Assuming a topic has [x,y] number of partitions when publishing, and there are b number of brokers.
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* and p is the number of partitions per topic.
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* if the broker number b <= x, then p = x.
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* if the broker number x < b < y, then x <= p <= b.
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* if the broker number b >= y, x <= p <= y
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Balance topic partitions to brokers
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===================================
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When the goal is to make sure that low traffic partitions can be merged, (and p >= x, and after last rebalance interval):
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1. Calculate the average load(throughput) of partitions per topic.
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2. If any two neighboring partitions have a load that is less than the average load, merge them.
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3. If min(b, y) < p, then merge two neighboring partitions that have the least combined load.
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When the goal is to make sure that high traffic partitions can be split, (and p < y and p < b, and after last rebalance interval):
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1. Calculate the average number of partitions per broker.
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2. If any partition has a load that is more than the average load, split it into two partitions.
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When the goal is to make sure that each broker has the same number of partitions:
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1. Calculate the average number of partitions per broker.
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2. For the brokers that have more than the average number of partitions, move the partitions to the brokers that have less than the average number of partitions.
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*/
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type BalanceAction interface {
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}
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type BalanceActionMerge struct {
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Before []topic.TopicPartition
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After topic.TopicPartition
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}
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type BalanceActionSplit struct {
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Before topic.TopicPartition
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After []topic.TopicPartition
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}
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type BalanceActionMove struct {
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TopicPartition topic.TopicPartition
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SourceBroker string
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TargetBroker string
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}
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type BalanceActionCreate struct {
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TopicPartition topic.TopicPartition
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TargetBroker string
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}
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// BalancePublishers check the stats of all brokers,
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// and balance the publishers to the brokers.
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func (balancer *PubBalancer) BalancePublishers() []BalanceAction {
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action := BalanceTopicPartitionOnBrokers(balancer.Brokers)
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return []BalanceAction{action}
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}
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func (balancer *PubBalancer) ExecuteBalanceAction(actions []BalanceAction, grpcDialOption grpc.DialOption) (err error) {
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for _, action := range actions {
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switch action.(type) {
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case *BalanceActionMove:
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err = balancer.ExecuteBalanceActionMove(action.(*BalanceActionMove), grpcDialOption)
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}
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if err != nil {
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return err
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}
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}
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return nil
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}
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