[#901] *: release worker pools where possible

Some of the pools are initialized during config initialization,
so it isn't possible currently to release them in one place.

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

pkg/local_object_storage/shard/gc.go

@@ -150,6 +150,9 @@ func (gc *gc) tickRemover() {
 	for {
 		select {
 		case <-gc.stopChannel:
+			if gc.workerPool != nil {
+				gc.workerPool.Release()
+			}
 			gc.log.Debug("GC is stopped")
 			return
 		case <-timer.C:

pkg/services/audit/auditor/pdp.go

@@ -33,6 +33,7 @@ func (c *Context) processPairs() {
 	}
 
 	wg.Wait()
+	c.pdpWorkerPool.Release()
 }
 
 func (c *Context) processPair(p *gamePair) {

pkg/services/audit/auditor/por.go

@@ -30,6 +30,7 @@ func (c *Context) executePoR() {
 	}
 
 	wg.Wait()
+	c.porWorkerPool.Release()
 
 	c.report.SetPoRCounters(c.porRequests.Load(), c.porRetries.Load())
 }

pkg/services/audit/taskmanager/listen.go

@@ -24,6 +24,7 @@ func (m *Manager) Listen(ctx context.Context) {
 			m.log.Warn("stop listener by context",
 				zap.String("error", ctx.Err().Error()),
 			)
+			m.workerPool.Release()
 
 			return
 		case task, ok := <-m.ch:

pkg/services/audit/taskmanager/manager.go

@@ -91,6 +91,7 @@ func WithMaxPDPSleepInterval(dur time.Duration) Option {
 }
 
 // WithPDPWorkerPoolGenerator returns option to set worker pool for PDP pairs processing.
+// Callback caller owns returned pool and must release it appropriately.
 func WithPDPWorkerPoolGenerator(f func() (util.WorkerPool, error)) Option {
 	return func(c *cfg) {
 		c.pdpPoolGenerator = f
@@ -98,6 +99,7 @@ func WithPDPWorkerPoolGenerator(f func() (util.WorkerPool, error)) Option {
 }
 
 // WithPoRWorkerPoolGenerator returns option to set worker pool for PoR SG processing.
+// Callback caller owns returned pool and must release it appropriately.
 func WithPoRWorkerPoolGenerator(f func() (util.WorkerPool, error)) Option {
 	return func(c *cfg) {
 		c.porPoolGenerator = f