[performance] Bump default workers to CPUs * 2 (#608)

* add license text to workers.go
* bump default workers to maxprocs*2

internal/concurrency/workers.go

@@ -1,3 +1,21 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
 package concurrency
 
 import (
@@ -27,7 +45,7 @@ func NewWorkerPool[MsgType any](workers int, queueRatio int) *WorkerPool[MsgType
 
 	if workers < 1 {
 		// ensure sensible workers
-		workers = runtime.GOMAXPROCS(0)
+		workers = runtime.GOMAXPROCS(0) * 2
 	}
 	if queueRatio < 1 {
 		// ensure sensible ratio