Prevent hang when deleting while streaming (#3169)

internal/manager/running_streams.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"io"
 	"net/http"
+	"time"
 
 	"github.com/stashapp/stash/internal/manager/config"
 	"github.com/stashapp/stash/internal/static"
@@ -46,7 +47,21 @@ func (c *StreamRequestContext) Cancel() {
 			if err != nil {
 				logger.Warnf("unable to write end of stream: %v", err)
 			}
+
+			// flush the buffer, but don't wait indefinitely
+			timeout := make(chan struct{}, 1)
+			go func() {
 				_ = bw.Flush()
+				close(timeout)
+			}()
+
+			const waitTime = time.Second
+
+			select {
+			case <-timeout:
+			case <-time.After(waitTime):
+				logger.Warnf("unable to flush buffer - closing connection")
+			}
 		}
 
 		conn.Close()