ensure kv semaphore has at least 2 count

kv/mdbx/kv_mdbx.go

@@ -281,7 +281,11 @@ func (opts MdbxOpts) Open() (kv.RwDB, error) {
 	}
 
 	if opts.roTxsLimiter == nil {
-		opts.roTxsLimiter = semaphore.NewWeighted(int64(runtime.GOMAXPROCS(-1)) - 1) // 1 less than max to allow unlocking to happen
+		targetSemCount := int64(runtime.GOMAXPROCS(-1)) - 1
+		if targetSemCount <= 1 {
+			targetSemCount = 2
+		}
+		opts.roTxsLimiter = semaphore.NewWeighted(targetSemCount) // 1 less than max to allow unlocking to happen
 	}
 	db := &MdbxKV{
 		opts:         opts,

kv/remotedb/kv_remote.go

@@ -69,12 +69,17 @@ func (opts remoteOpts) WithBucketsConfig(f mdbx.TableCfgFunc) remoteOpts {
 }
 
 func (opts remoteOpts) Open() (*RemoteKV, error) {
+	targetSemCount := int64(runtime.GOMAXPROCS(-1)) - 1
+	if targetSemCount <= 1 {
+		targetSemCount = 2
+	}
+
 	db := &RemoteKV{
 		opts:         opts,
 		remoteKV:     opts.remoteKV,
 		log:          log.New("remote_db", opts.DialAddress),
 		buckets:      kv.TableCfg{},
-		roTxsLimiter: semaphore.NewWeighted(int64(runtime.GOMAXPROCS(-1)) - 1), // 1 less than max to allow unlocking
+		roTxsLimiter: semaphore.NewWeighted(targetSemCount), // 1 less than max to allow unlocking
 	}
 	customBuckets := opts.bucketsCfg(kv.ChaindataTablesCfg)
 	for name, cfg := range customBuckets { // copy map to avoid changing global variable