fix: add missing concurrency lock (#2098)

internal/collector/service/service.go

@@ -143,7 +143,7 @@ func (c *Collector) Build(logger *slog.Logger, _ *mi.Session) error {
 		},
 	}
 
-	c.queryAllServicesBuffer = make([]byte, 1024*100)
+	c.queryAllServicesBuffer = make([]byte, 1024*200)
 
 	c.info = prometheus.NewDesc(
 		prometheus.BuildFQName(types.Namespace, Name, "info"),
@@ -242,6 +242,15 @@ func (c *Collector) Collect(ch chan<- prometheus.Metric) error {
 }
 
 func (c *Collector) collectWorker(ch chan<- prometheus.Metric, service windows.ENUM_SERVICE_STATUS_PROCESS) {
+	if uintptr(unsafe.Pointer(service.ServiceName)) == uintptr(windows.InvalidHandle) {
+		c.logger.Log(context.Background(), slog.LevelWarn, "failed collecting service info",
+			slog.String("err", "ServiceName is 0xffffffffffffffff"),
+			slog.String("service", fmt.Sprintf("%+v", service)),
+		)
+
+		return
+	}
+
 	serviceName := windows.UTF16PtrToString(service.ServiceName)
 
 	if c.config.ServiceExclude.MatchString(serviceName) || !c.config.ServiceInclude.MatchString(serviceName) {
@@ -375,6 +384,8 @@ func (c *Collector) queryAllServices() ([]windows.ENUM_SERVICE_STATUS_PROCESS, e
 		err                   error
 	)
 
+	clear(c.queryAllServicesBuffer)
+
 	for {
 		currentBufferSize := uint32(cap(c.queryAllServicesBuffer))
 

internal/httphandler/httphandler.go

@@ -42,9 +42,8 @@ type MetricsHTTPHandler struct {
 	// the exporter itself.
 	exporterMetricsRegistry *prometheus.Registry
 
-	logger        *slog.Logger
-	options       Options
-	concurrencyCh chan struct{}
+	logger  *slog.Logger
+	options Options
 }
 
 type Options struct {
@@ -64,9 +63,6 @@ func New(logger *slog.Logger, metricCollectors *collector.Collection, options *O
 		metricCollectors: metricCollectors,
 		logger:           logger,
 		options:          *options,
-
-		// We are expose metrics directly from the memory region of the Win32 API. We should not allow more than one request at a time.
-		concurrencyCh: make(chan struct{}, 1),
 	}
 
 	if !options.DisableExporterMetrics {

pkg/collector/handler.go

@@ -20,6 +20,7 @@ package collector
 import (
 	"fmt"
 	"log/slog"
+	"sync"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -28,6 +29,12 @@ import (
 // Interface guard.
 var _ prometheus.Collector = (*Handler)(nil)
 
+// We are expose metrics directly from the memory region of the Win32 API.
+// We should not allow more than one request at a time.
+//
+//nolint:gochecknoglobals
+var concurrencyMu sync.Mutex
+
 // Handler implements [prometheus.Collector] for a set of Windows Collection.
 type Handler struct {
 	maxScrapeDuration time.Duration
@@ -60,5 +67,7 @@ func (p *Handler) Describe(_ chan<- *prometheus.Desc) {}
 // Collect sends the collected metrics from each of the Collection to
 // prometheus.
 func (p *Handler) Collect(ch chan<- prometheus.Metric) {
+	concurrencyMu.Lock()
 	p.collection.collectAll(ch, p.logger, p.maxScrapeDuration)
+	concurrencyMu.Unlock()
 }