supervisor: Avoid spawning two Goroutines for logging purposes

We use different loggers for both stdout and stderr of processes spawned
by our supervisor. And while these loggers aren't any different, this
means that we now also have two Goroutines copying the process's output
into the loggers.

Let's improve this and only use a single Goroutine by reusing the same
log writer for both streams.

1 files changed, 5 insertions, 2 deletions

diff --git a/internal/supervisor/supervisor.go b/internal/supervisor/supervisor.go
index f695b071e..0c7310817 100644
--- a/internal/supervisor/supervisor.go
+++ b/internal/supervisor/supervisor.go
@@ -93,11 +93,14 @@ func New(config Config, name string, env []string, args []string, dir string, me
 func (p *Process) start(logger *log.Entry) (*exec.Cmd, error) {
 	startCounter.WithLabelValues(p.Name).Inc()
 
+	logWriter := logger.WriterLevel(log.InfoLevel)
+
 	cmd := exec.Command(p.args[0], p.args[1:]...)
 	cmd.Env = p.env
 	cmd.Dir = p.dir
-	cmd.Stdout = logger.WriterLevel(log.InfoLevel)
-	cmd.Stderr = logger.WriterLevel(log.InfoLevel)
+	cmd.Stdout = logWriter
+	cmd.Stderr = logWriter
+
 	return cmd, cmd.Start()
 }