defers putting slice back into pool on ingester push to prevent panicking Error() calls which reference underlying labels (#2000)

Signed-off-by: Owen Diehl <ow.diehl@gmail.com>

Author: owen-d

pkg/ingester/ingester.go

@@ -226,6 +226,8 @@ func (i *Ingester) Push(ctx old_ctx.Context, req *client.WriteRequest) (*client.
 		return i.v2Push(ctx, req)
 	}
 
+	defer client.ReuseSlice(req.Timeseries)
+
 	userID, err := user.ExtractOrgID(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("no user id")
@@ -248,7 +250,6 @@ func (i *Ingester) Push(ctx old_ctx.Context, req *client.WriteRequest) (*client.
 			return nil, wrapWithUser(err, userID)
 		}
 	}
-	client.ReuseSlice(req.Timeseries)
 
 	if lastPartialErr != nil {
 		return &client.WriteResponse{}, lastPartialErr.WrapWithUser(userID).WrappedError()

pkg/ingester/ingester_v2.go

@@ -105,6 +105,8 @@ func NewV2(cfg Config, clientConfig client.Config, limits *validation.Overrides,
 func (i *Ingester) v2Push(ctx old_ctx.Context, req *client.WriteRequest) (*client.WriteResponse, error) {
 	var firstPartialErr error
 
+	defer client.ReuseSlice(req.Timeseries)
+
 	userID, err := user.ExtractOrgID(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("no user id")
@@ -183,8 +185,6 @@ func (i *Ingester) v2Push(ctx old_ctx.Context, req *client.WriteRequest) (*clien
 	i.metrics.ingestedSamples.Add(float64(succeededSamplesCount))
 	i.metrics.ingestedSamplesFail.Add(float64(failedSamplesCount))
 
-	client.ReuseSlice(req.Timeseries)
-
 	if firstPartialErr != nil {
 		return &client.WriteResponse{}, httpgrpc.Errorf(http.StatusBadRequest, wrapWithUser(firstPartialErr, userID).Error())
 	}