use a named lock instead of a single per-pool mutex.

utils.go

@@ -3,10 +3,22 @@ package nostr
 import (
 	"net/url"
 	"strings"
+	"sync"
 
+	"github.com/dgraph-io/ristretto/z"
 	"golang.org/x/exp/constraints"
 )
 
+const MAX_LOCKS = 50
+
+var namedMutexPool = make([]sync.Mutex, MAX_LOCKS)
+
+func namedLock(name string) (unlock func()) {
+	idx := z.MemHashString(name) % MAX_LOCKS
+	namedMutexPool[idx].Lock()
+	return namedMutexPool[idx].Unlock
+}
+
 func similar[E constraints.Ordered](as, bs []E) bool {
 	if len(as) != len(bs) {
 		return false