⚡ when high concurrency occurs, the connection is full and the connection is rejected.

Signed-off-by: cuisongliu <cuisongliu@qq.com>

Author: cuisongliu

api/client.go

@@ -75,6 +75,7 @@ func (cfg *Config) validate() error {
 
 // Client is the interface for an API client.
 type Client interface {
+	CloseIdleConnections()
 	URL(ep string, args map[string]string) *url.URL
 	Do(context.Context, *http.Request) (*http.Response, []byte, error)
 }
@@ -118,10 +119,15 @@ func (c *httpClient) URL(ep string, args map[string]string) *url.URL {
 	return &u
 }
 
+func (c *httpClient) CloseIdleConnections() {
+	c.client.CloseIdleConnections()
+}
+
 func (c *httpClient) Do(ctx context.Context, req *http.Request) (*http.Response, []byte, error) {
 	if ctx != nil {
 		req = req.WithContext(ctx)
 	}
+	defer c.client.CloseIdleConnections()
 	resp, err := c.client.Do(req)
 	defer func() {
 		if resp != nil {

api/prometheus/v1/api.go

@@ -1342,6 +1342,7 @@ type Warnings []string
 // apiClient wraps a regular client and processes successful API responses.
 // Successful also includes responses that errored at the API level.
 type apiClient interface {
+	CloseIdleConnections()
 	URL(ep string, args map[string]string) *url.URL
 	Do(context.Context, *http.Request) (*http.Response, []byte, Warnings, error)
 	DoGetFallback(ctx context.Context, u *url.URL, args url.Values) (*http.Response, []byte, Warnings, error)
@@ -1374,6 +1375,10 @@ func errorTypeAndMsgFor(resp *http.Response) (ErrorType, string) {
 	return ErrBadResponse, fmt.Sprintf("bad response code %d", resp.StatusCode)
 }
 
+func (h *apiClientImpl) CloseIdleConnections() {
+	h.client.CloseIdleConnections()
+}
+
 func (h *apiClientImpl) URL(ep string, args map[string]string) *url.URL {
 	return h.client.URL(ep, args)
 }

api/prometheus/v1/api_test.go

@@ -62,6 +62,9 @@ func (c *apiTestClient) URL(ep string, args map[string]string) *url.URL {
 	return u
 }
 
+func (c *apiTestClient) CloseIdleConnections() {
+}
+
 func (c *apiTestClient) Do(_ context.Context, req *http.Request) (*http.Response, []byte, Warnings, error) {
 	test := c.curTest
 
@@ -1263,6 +1266,9 @@ type apiClientTest struct {
 	expectedWarnings Warnings
 }
 
+func (c *testClient) CloseIdleConnections() {
+}
+
 func (c *testClient) URL(ep string, args map[string]string) *url.URL {
 	return nil
 }
@@ -1734,6 +1740,10 @@ type httpTestClient struct {
 	client http.Client
 }
 
+func (c *httpTestClient) CloseIdleConnections() {
+	c.client.CloseIdleConnections()
+}
+
 func (c *httpTestClient) URL(ep string, args map[string]string) *url.URL {
 	return nil
 }