seaweedfs/weed/mq/balancer/balancer.go
2023-09-30 13:19:05 -07:00

110 lines
3.4 KiB
Go

package balancer
import (
"fmt"
cmap "github.com/orcaman/concurrent-map/v2"
"github.com/seaweedfs/seaweedfs/weed/mq/topic"
"github.com/seaweedfs/seaweedfs/weed/pb/mq_pb"
)
const (
MaxPartitionCount = 8 * 9 * 5 * 7 //2520
LockBrokerBalancer = "broker_balancer"
)
// Balancer collects stats from all brokers.
//
// When publishers wants to create topics, it picks brokers to assign the topic partitions.
// When consumers wants to subscribe topics, it tells which brokers are serving the topic partitions.
//
// When a partition needs to be split or merged, or a partition needs to be moved to another broker,
// the balancer will let the broker tell the consumer instance to stop processing the partition.
// The existing consumer instance will flush the internal state, and then stop processing.
// Then the balancer will tell the brokers to start sending new messages in the new/moved partition to the consumer instances.
//
// Failover to standby consumer instances:
//
// A consumer group can have min and max number of consumer instances.
// For consumer instances joined after the max number, they will be in standby mode.
//
// When a consumer instance is down, the broker will notice this and inform the balancer.
// The balancer will then tell the broker to send the partition to another standby consumer instance.
type Balancer struct {
Brokers cmap.ConcurrentMap[string, *BrokerStats]
}
type BrokerStats struct {
TopicPartitionCount int32
ConsumerCount int32
CpuUsagePercent int32
Stats cmap.ConcurrentMap[string, *TopicPartitionStats]
}
func (bs *BrokerStats) UpdateStats(stats *mq_pb.BrokerStats) {
bs.TopicPartitionCount = int32(len(stats.Stats))
bs.CpuUsagePercent = stats.CpuUsagePercent
var consumerCount int32
currentTopicPartitions := bs.Stats.Items()
for _, topicPartitionStats := range stats.Stats {
tps := &TopicPartitionStats{
TopicPartition: topic.TopicPartition{
Namespace: topicPartitionStats.Topic.Namespace,
Topic: topicPartitionStats.Topic.Name,
RangeStart: topicPartitionStats.Partition.RangeStart,
RangeStop: topicPartitionStats.Partition.RangeStop,
},
ConsumerCount: topicPartitionStats.ConsumerCount,
IsLeader: topicPartitionStats.IsLeader,
}
consumerCount += topicPartitionStats.ConsumerCount
key := tps.TopicPartition.String()
bs.Stats.Set(key, tps)
delete(currentTopicPartitions, key)
}
// remove the topic partitions that are not in the stats
for key := range currentTopicPartitions {
bs.Stats.Remove(key)
}
bs.ConsumerCount = consumerCount
}
func (bs *BrokerStats) RegisterAssignment(t *mq_pb.Topic, partition *mq_pb.Partition) {
tps := &TopicPartitionStats{
TopicPartition: topic.TopicPartition{
Namespace: t.Namespace,
Topic: t.Name,
RangeStart: partition.RangeStart,
RangeStop: partition.RangeStop,
},
ConsumerCount: 0,
IsLeader: true,
}
key := tps.TopicPartition.String()
bs.Stats.Set(key, tps)
}
func (bs *BrokerStats) String() string {
return fmt.Sprintf("BrokerStats{TopicPartitionCount:%d, ConsumerCount:%d, CpuUsagePercent:%d, Stats:%+v}",
bs.TopicPartitionCount, bs.ConsumerCount, bs.CpuUsagePercent, bs.Stats.Items())
}
type TopicPartitionStats struct {
topic.TopicPartition
ConsumerCount int32
IsLeader bool
}
func NewBalancer() *Balancer {
return &Balancer{
Brokers: cmap.New[*BrokerStats](),
}
}
func NewBrokerStats() *BrokerStats {
return &BrokerStats{
Stats: cmap.New[*TopicPartitionStats](),
}
}