Consistent-Hashing is a Go library designed for distributed load balancing using consistent hashing, enhanced with bounded loads. It provides efficient key distribution across a set of hosts while ensuring that no single host becomes overloaded beyond a specified limit.
To install the package, execute the following command:
go get github.com/ArchishmanSengupta/consistent-hashingHere's a straightforward example of how to utilize the consistent_hashing package:
package main
import (
"context"
"fmt"
"log"
"github.com/ArchishmanSengupta/consistent-hashing"
)
func main() {
// Create a new ConsistentHashing instance with default configuration
ch, err := consistent_hashing.NewWithConfig(consistent_hashing.Config{})
if err != nil {
log.Fatal(err)
}
// Add hosts to the consistent hash ring
hosts := []string{"host1", "host2", "host3", "host4"}
ctx := context.Background()
for _, host := range hosts {
err := ch.Add(ctx, host)
if err != nil {
log.Printf("Error adding host %s: %v", host, err)
}
}
// Distribute some keys
keys := []string{"key1", "key2", "key3", "key4", "key5"}
for _, key := range keys {
host, err := ch.GetLeast(ctx, key)
if err != nil {
log.Printf("Error getting host for key %s: %v", key, err)
continue
}
fmt.Printf("Key %s assigned to host %s\n", key, host)
// Increase the load for the assigned host
err = ch.IncreaseLoad(ctx, host)
if err != nil {
log.Printf("Error increasing load for host %s: %v", host, err)
}
}
// Print current loads
loads := ch.GetLoads()
fmt.Println("Current loads:")
for host, load := range loads {
fmt.Printf("%s: %d\n", host, load)
}
// Remove a host from the ring
hostToRemove := "host2"
err = ch.Remove(ctx, hostToRemove)
if err != nil {
log.Printf("Error removing host %s: %v", hostToRemove, err)
}
// Print updated list of hosts
fmt.Println("Remaining hosts after removal:", ch.Hosts())
}Key key1 assigned to host host4
Key key2 assigned to host host3
Key key3 assigned to host host2
Key key4 assigned to host host1
Key key5 assigned to host host4
Current loads:
host2: 1
host3: 1
host4: 2
host1: 1
Remaining hosts after removal: [host1 host3 host4]
- Consistent Hashing with Bounded Loads: Distributes load evenly across hosts while limiting maximum host load.
- Customizable Configuration: Adjust replication factor, load factor, and hash function to suit specific requirements.
- Thread-Safe Operations: Ensures safe concurrent access for adding hosts, distributing keys, and managing loads.
- Efficient Key Distribution: Uses consistent hashing principles for efficient key assignment and lookup.
Customize consistent hashing behavior by providing a Config struct during instance creation:
cfg := consistent_hashing.Config{
ReplicationFactor: 20, // Number of virtual nodes per host
LoadFactor: 1.25, // Maximum load factor before redistribution
HashFunction: fnv.New64a, // Custom hash function (optional)
}
ch, err := consistent_hashing.NewWithConfig(cfg)Use the following command to run benchmarks:
go test -bench=. -benchmemExample benchmark results:
goos: darwin
goarch: arm64
pkg: github.com/ArchishmanSengupta/consistent-hashing
BenchmarkAdd-10 4626 19088168 ns/op 23748 B/op 895 allocs/op
BenchmarkGet-10 6359968 186.5 ns/op 47 B/op 4 allocs/op
BenchmarkGetLeast-10 180 6606643 ns/op 24 B/op 3 allocs/op
BenchmarkIncreaseLoad-10 13727469 83.96 ns/op 13 B/op 1 allocs/op
BenchmarkRemove-10 139 8671612 ns/op 17696 B/op 1306 allocs/op
BenchmarkParallelOperations-10 884 1297025 ns/op 123 B/op 9 allocs/op
PASS
ok github.com/ArchishmanSengupta/consistent-hashing 160.723s
NewWithConfig(cfg Config) (*ConsistentHashing, error): Creates a new instance of ConsistentHashing with specified configuration.Add(ctx context.Context, host string) error: Adds a new host to the consistent hash ring.Get(ctx context.Context, key string) (string, error): Retrieves the host responsible for a given key.GetLeast(ctx context.Context, key string) (string, error): Retrieves the least loaded host for a given key.IncreaseLoad(ctx context.Context, host string) error: Increases the load for a specified host.DecreaseLoad(ctx context.Context, host string) error: Decreases the load for a specified host.GetLoads() map[string]int64: Retrieves the current load for all hosts.Hosts() []string: Retrieves the list of all hosts in the ring.Remove(ctx context.Context, host string) error: Removes a host from the ring.
ch, _ := consistent_hashing.NewWithConfig(consistent_hashing.Config{})
ctx := context.Background()
// Adding hosts
ch.Add(ctx, "host1")
ch.Add(ctx, "host2")
ch.Add(ctx, "host3")
// Removing a host
err := ch.Remove(ctx, "host2")
if err != nil {
log.Printf("Error removing host: %v", err)
}
fmt.Println("Current hosts:", ch.Hosts())ch, _ := consistent_hashing.NewWithConfig(consistent_hashing.Config{})
ctx := context.Background()
// Add hosts
for i := 1; i <= 5; i++ {
ch.Add(ctx, fmt.Sprintf("host%d", i))
}
// Distribute keys
keys := []string{"user1", "user2", "user3", "user4", "user5", "user6", "user7", "user8", "user9", "user10"}
for _, key := range keys {
host, _ := ch.GetLeast(ctx, key)
fmt.Printf("Key %s assigned to %s\n", key, host)
ch.IncreaseLoad(ctx, host)
}
// Print final loads
loads := ch.GetLoads()
for host, load := range loads {
fmt.Printf("%s load: %d\n", host, load)
}Contributions are welcome! Feel free to submit a Pull Request with your enhancements or bug fixes.
This README now includes detailed instructions on adding, removing hosts, and showcases example usage scenarios for distributing keys and benchmarking performance. It should provide comprehensive guidance for users looking to integrate and leverage the Consistent-Hashing library effectively.