engine: support reloading shard_pool_size with SIGHUP

Refs #1770.

Signed-off-by: Andrey Butusov <[email protected]>

cmd/neofs-node/config.go

@@ -866,6 +866,7 @@ func (c *cfg) configWatcher(ctx context.Context) {
 			for _, optsWithID := range c.shardOpts() {
 				rcfg.AddShard(optsWithID.configID, optsWithID.shOpts)
 			}
+			rcfg.SetShardPoolSize(c.engine.shardPoolSize)
 
 			err = c.cfgObject.cfgLocalStorage.localStorage.Reload(rcfg)
 			if err != nil {

pkg/local_object_storage/engine/control.go

@@ -191,12 +191,19 @@ func (rCfg *ReConfiguration) AddShard(id string, opts []shard.Option) {
 
 // Reload reloads StorageEngine's configuration in runtime.
 func (e *StorageEngine) Reload(rcfg ReConfiguration) error {
+	e.mtx.Lock()
+	e.shardPoolSize = rcfg.shardPoolSize
+	e.mtx.Unlock()
+
 	type reloadInfo struct {
 		sh   *shard.Shard
 		opts []shard.Option
 	}
 
 	e.mtx.RLock()
+	for _, pool := range e.shardPools {
+		pool.Tune(int(e.shardPoolSize))
+	}
 
 	var shardsToRemove []string // shards IDs
 	var shardsToAdd []string    // shard config identifiers (blobstor paths concatenation)