Repository: kubernetes-sigs/cloud-provider-azure
Pull request #959 (2021-12-30 06:41:32)

feat: support sending sync requests concurrently in batches when putting vmss vm
(cherry picked from commit d9edcd6ec1429d8995d985b1ebddbce77bfd25ad)

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#### What type of PR is this?

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/kind feature

#### What this PR does / why we need it:

Cherry pick of #953: feat: support sending sync requests concurrently in batches when putting vmss vm

#### Which issue(s) this PR fixes:
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Fixes #

#### Special notes for your reviewer:

#### Does this PR introduce a user-facing change?
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```release-note
Introduce a configuration option `putVMSSVMBatchSize`. If set, the sync requests will be sent concurrently in batches when putting vmss vms.
```

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k8s-ci-robot: [APPROVALNOTIFIER] This PR is **APPROVED**

This pull-request has been approved by: *<a href="https://github.com/kubernetes-sigs/cloud-provider-azure/pull/959#" title="Author self-approved">nilo19</a>*

The full list of commands accepted by this bot can be found [here](https://go.k8s.io/bot-commands?repo=kubernetes-sigs%2Fcloud-provider-azure).

The pull request process is described [here](https://git.k8s.io/community/contributors/guide/owners.md#the-code-review-process)

<details >
Needs approval from an approver in each of these files:

- ~~[OWNERS](https://github.com/kubernetes-sigs/cloud-provider-azure/blob/release-1.1/OWNERS)~~ [nilo19]

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Patch:
diff --git a/pkg/azureclients/armclient/azure_armclient.go b/pkg/azureclients/armclient/azure_armclient.go
index 895f01bfa..443cbbe7e 100644
--- a/pkg/azureclients/armclient/azure_armclient.go
+++ b/pkg/azureclients/armclient/azure_armclient.go
@@ -395,46 +395,7 @@ func (c *Client) PutResource(ctx context.Context, resourceID string, parameters
 	return c.PutResourceWithDecorators(ctx, resourceID, parameters, putDecorators)
 }
 
-// PutResources puts a list of resources from resources map[resourceID]parameters.
-// Those resources sync requests are sequential while async requests are concurrent. It's especially
-// useful when the ARM API doesn't support concurrent requests.
-func (c *Client) PutResources(ctx context.Context, resources map[string]interface{}) map[string]*PutResourcesResponse {
-	if len(resources) == 0 {
-		return nil
-	}
-
-	// Sequential sync requests.
-	futures := make(map[string]*azure.Future)
-	responses := make(map[string]*PutResourcesResponse)
-	for resourceID, parameters := range resources {
-		decorators := []autorest.PrepareDecorator{
-			autorest.WithPathParameters("{resourceID}", map[string]interface{}{"resourceID": resourceID}),
-			autorest.WithJSON(parameters),
-		}
-		request, err := c.PreparePutRequest(ctx, decorators...)
-		if err != nil {
-			klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "put.prepare", resourceID, err)
-			responses[resourceID] = &PutResourcesResponse{
-				Error: retry.NewError(false, err),
-			}
-			continue
-		}
-		dumpRequest(request, 10)
-
-		future, resp, clientErr := c.SendAsync(ctx, request)
-		defer c.CloseResponse(ctx, resp)
-		if clientErr != nil {
-			klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "put.send", resourceID, clientErr.Error())
-			responses[resourceID] = &PutResourcesResponse{
-				Error: clientErr,
-			}
-			continue
-		}
-
-		futures[resourceID] = future
-	}
-
-	// Concurrent async requests.
+func (c *Client) waitAsync(ctx context.Context, futures map[string]*azure.Future, previousResponses map[string]*PutResourcesResponse) {
 	wg := sync.WaitGroup{}
 	var responseLock sync.Mutex
 	for resourceID, future := range futures {
@@ -457,22 +418,111 @@ func (c *Client) PutResources(ctx context.Context, resources map[string]interfac
 				}
 
 				responseLock.Lock()
-				responses[resourceID] = &PutResourcesResponse{
+				previousResponses[resourceID] = &PutResourcesResponse{
 					Error: retriableErr,
 				}
 				responseLock.Unlock()
 				return
 			}
+		}(resourceID, future)
+	}
+	wg.Wait()
+}
+
+// PutResources puts a list of resources from resources map[resourceID]parameters.
+// Those resources sync requests are sequential while async requests are concurrent. It's especially
+// useful when the ARM API doesn't support concurrent requests.
+func (c *Client) PutResources(ctx context.Context, resources map[string]interface{}) map[string]*PutResourcesResponse {
+	if len(resources) == 0 {
+		return nil
+	}
 
-			responseLock.Lock()
+	// Sequential sync requests.
+	futures := make(map[string]*azure.Future)
+	responses := make(map[string]*PutResourcesResponse)
+	for resourceID, parameters := range resources {
+		future, rerr := c.PutResourceAsync(ctx, resourceID, parameters)
+		if rerr != nil {
 			responses[resourceID] = &PutResourcesResponse{
-				Response: response,
+				Error: rerr,
 			}
-			responseLock.Unlock()
-		}(resourceID, future)
+			continue
+		}
+		futures[resourceID] = future
 	}
 
-	wg.Wait()
+	c.waitAsync(ctx, futures, responses)
+
+	return responses
+}
+
+// PutResourcesInBatches is similar with PutResources, but it sends sync request concurrently in batches.
+func (c *Client) PutResourcesInBatches(ctx context.Context, resources map[string]interface{}, batchSize int) map[string]*PutResourcesResponse {
+	if len(resources) == 0 {
+		return nil
+	}
+
+	if batchSize <= 0 {
+		klog.V(4).Infof("PutResourcesInBatches: batch size %d, put resources in sequence", batchSize)
+		return c.PutResources(ctx, resources)
+	}
+
+	if batchSize > len(resources) {
+		klog.V(4).Infof("PutResourcesInBatches: batch size %d, but the number of the resources is %d", batchSize, resources)
+		batchSize = len(resources)
+	}
+	klog.V(4).Infof("PutResourcesInBatches: send sync requests in parallel with the batch size %d", batchSize)
+
+	// Convert map to slice because it is more straightforward to
+	// loop over slice in batches than map.
+	type resourcesMeta struct {
+		resourceID string
+		parameters interface{}
+	}
+	resourcesList := make([]resourcesMeta, 0)
+	for resourceID, parameters := range resources {
+		resourcesList = append(resourcesList, resourcesMeta{
+			resourceID: resourceID,
+			parameters: parameters,
+		})
+	}
+
+	// Concurrent sync requests in batches.
+	futures := make(map[string]*azure.Future)
+	responses := make(map[string]*PutResourcesResponse)
+	wg := sync.WaitGroup{}
+	var responseLock, futuresLock sync.Mutex
+	for i := 0; i < len(resourcesList); i += batchSize {
+		j := i + batchSize
+		if j > len(resourcesList) {
+			j = len(resourcesList)
+		}
+
+		for k := i; k < j; k++ {
+			wg.Add(1)
+			go func(resourceID string, parameters interface{}) {
+				defer wg.Done()
+				future, rerr := c.PutResourceAsync(ctx, resourceID, parameters)
+				if rerr != nil {
+					responseLock.Lock()
+					responses[resourceID] = &PutResourcesResponse{
+						Error: rerr,
+					}
+					responseLock.Unlock()
+					return
+				}
+
+				futuresLock.Lock()
+				futures[resourceID] = future
+				futuresLock.Unlock()
+			}(resourcesList[k].resourceID, resourcesList[k].parameters)
+		}
+		wg.Wait()
+	}
+
+	// Concurrent async requests.
+	c.waitAsync(ctx, futures, responses)
+
 	return responses
 }
 
diff --git a/pkg/azureclients/armclient/interface.go b/pkg/azureclients/armclient/interface.go
index 48d6de8a3..d3f38239e 100644
--- a/pkg/azureclients/armclient/interface.go
+++ b/pkg/azureclients/armclient/interface.go
@@ -70,6 +70,9 @@ type Interface interface {
 	// useful when the ARM API doesn't support concurrent requests.
 	PutResources(ctx context.Context, resources map[string]interface{}) map[string]*PutResourcesResponse
 
+	// PutResourcesInBatches is similar with PutResources, but it sends sync request concurrently in batches.
+	PutResourcesInBatches(ctx context.Context, resources map[string]interface{}, batchSize int) map[string]*PutResourcesResponse
+
 	// PutResourceWithDecorators puts a resource with decorators by resource ID
 	PutResourceWithDecorators(ctx context.Context, resourceID string, parameters interface{}, decorators []autorest.PrepareDecorator) (*http.Response, *retry.Error)
 
diff --git a/pkg/azureclients/armclient/mockarmclient/interface.go b/pkg/azureclients/armclient/mockarmclient/interface.go
index 38bfbecd0..10aec4acf 100644
--- a/pkg/azureclients/armclient/mockarmclient/interface.go
+++ b/pkg/azureclients/armclient/mockarmclient/interface.go
@@ -23,40 +23,39 @@ package mockarmclient
 
 import (
 	context "context"
-	http "net/http"
-	reflect "reflect"
-
 	autorest "github.com/Azure/go-autorest/autorest"
 	azure "github.com/Azure/go-autorest/autorest/azure"
 	gomock "github.com/golang/mock/gomock"
+	http "net/http"
+	reflect "reflect"
 	armclient "sigs.k8s.io/cloud-provider-azure/pkg/azureclients/armclient"
 	retry "sigs.k8s.io/cloud-provider-azure/pkg/retry"
 )
 
-// MockInterface is a mock of Interface interface.
+// MockInterface is a mock of Interface interface
 type MockInterface struct {
 	ctrl     *gomock.Controller
 	recorder *MockInterfaceMockRecorder
 }
 
-// MockInterfaceMockRecorder is the mock recorder for MockInterface.
+// MockInterfaceMockRecorder is the mock recorder for MockInterface
 type MockInterfaceMockRecorder struct {
 	mock *MockInterface
 }
 
-// NewMockInterface creates a new mock instance.
+// NewMockInterface creates a new mock instance
 func NewMockInterface(ctrl *gomock.Controller) *MockInterface {
 	mock := &MockInterface{ctrl: ctrl}
 	mock.recorder = &MockInterfaceMockRecorder{mock}
 	return mock
 }
 
-// EXPECT returns an object that allows the caller to indicate expected use.
+// EXPECT returns an object that allows the caller to indicate expected use
 func (m *MockInterface) EXPECT() *MockInterfaceMockRecorder {
 	return m.recorder
 }
 
-// Send mocks base method.
+// Send mocks base method
 func (m *MockInterface) Send(ctx context.Context, request *http.Request) (*http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "Send", ctx, request)
@@ -65,13 +64,13 @@ func (m *MockInterface) Send(ctx context.Context, request *http.Request) (*http.
 	return ret0, ret1
 }
 
-// Send indicates an expected call of Send.
+// Send indicates an expected call of Send
 func (mr *MockInterfaceMockRecorder) Send(ctx, request interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Send", reflect.TypeOf((*MockInterface)(nil).Send), ctx, request)
 }
 
-// PreparePutRequest mocks base method.
+// PreparePutRequest mocks base method
 func (m *MockInterface) PreparePutRequest(ctx context.Context, decorators ...autorest.PrepareDecorator) (*http.Request, error) {
 	m.ctrl.T.Helper()
 	varargs := []interface{}{ctx}
@@ -84,14 +83,14 @@ func (m *MockInterface) PreparePutRequest(ctx context.Context, decorators ...aut
 	return ret0, ret1
 }
 
-// PreparePutRequest indicates an expected call of PreparePutRequest.
+// PreparePutRequest indicates an expected call of PreparePutRequest
 func (mr *MockInterfaceMockRecorder) PreparePutRequest(ctx interface{}, decorators ...interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	varargs := append([]interface{}{ctx}, decorators...)
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PreparePutRequest", reflect.TypeOf((*MockInterface)(nil).PreparePutRequest), varargs...)
 }
 
-// PreparePostRequest mocks base method.
+// PreparePostRequest mocks base method
 func (m *MockInterface) PreparePostRequest(ctx context.Context, decorators ...autorest.PrepareDecorator) (*http.Request, error) {
 	m.ctrl.T.Helper()
 	varargs := []interface{}{ctx}
@@ -104,14 +103,14 @@ func (m *MockInterface) PreparePostRequest(ctx context.Context, decorators ...au
 	return ret0, ret1
 }
 
-// PreparePostRequest indicates an expected call of PreparePostRequest.
+// PreparePostRequest indicates an expected call of PreparePostRequest
 func (mr *MockInterfaceMockRecorder) PreparePostRequest(ctx interface{}, decorators ...interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	varargs := append([]interface{}{ctx}, decorators...)
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PreparePostRequest", reflect.TypeOf((*MockInterface)(nil).PreparePostRequest), varargs...)
 }
 
-// PrepareGetRequest mocks base method.
+// PrepareGetRequest mocks base method
 func (m *MockInterface) PrepareGetRequest(ctx context.Context, decorators ...autorest.PrepareDecorator) (*http.Request, error) {
 	m.ctrl.T.Helper()
 	varargs := []interface{}{ctx}
@@ -124,14 +123,14 @@ func (m *MockInterface) PrepareGetRequest(ctx context.Context, decorators ...aut
 	return ret0, ret1
 }
 
-// PrepareGetRequest indicates an expected call of PrepareGetRequest.
+// PrepareGetRequest indicates an expected call of PrepareGetRequest
 func (mr *MockInterfaceMockRecorder) PrepareGetRequest(ctx interface{}, decorators ...interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	varargs := append([]interface{}{ctx}, decorators...)
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PrepareGetRequest", reflect.TypeOf((*MockInterface)(nil).PrepareGetRequest), varargs...)
 }
 
-// PrepareDeleteRequest mocks base method.
+// PrepareDeleteRequest mocks base method
 func (m *MockInterface) PrepareDeleteRequest(ctx context.Context, decorators ...autorest.PrepareDecorator) (*http.Request, error) {
 	m.ctrl.T.Helper()
 	varargs := []interface{}{ctx}
@@ -144,14 +143,14 @@ func (m *MockInterface) PrepareDeleteRequest(ctx context.Context, decorators ...
 	return ret0, ret1
 }
 
-// PrepareDeleteRequest indicates an expected call of PrepareDeleteRequest.
+// PrepareDeleteRequest indicates an expected call of PrepareDeleteRequest
 func (mr *MockInterfaceMockRecorder) PrepareDeleteRequest(ctx interface{}, decorators ...interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	varargs := append([]interface{}{ctx}, decorators...)
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PrepareDeleteRequest", reflect.TypeOf((*MockInterface)(nil).PrepareDeleteRequest), varargs...)
 }
 
-// PrepareHeadRequest mocks base method.
+// PrepareHeadRequest mocks base method
 func (m *MockInterface) PrepareHeadRequest(ctx context.Context, decorators ...autorest.PrepareDecorator) (*http.Request, error) {
 	m.ctrl.T.Helper()
 	varargs := []interface{}{ctx}
@@ -164,14 +163,14 @@ func (m *MockInterface) PrepareHeadRequest(ctx context.Context, decorators ...au
 	return ret0, ret1
 }
 
-// PrepareHeadRequest indicates an expected call of PrepareHeadRequest.
+// PrepareHeadRequest indicates an expected call of PrepareHeadRequest
 func (mr *MockInterfaceMockRecorder) PrepareHeadRequest(ctx interface{}, decorators ...interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	varargs := append([]interface{}{ctx}, decorators...)
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PrepareHeadRequest", reflect.TypeOf((*MockInterface)(nil).PrepareHeadRequest), varargs...)
 }
 
-// WaitForAsyncOperationCompletion mocks base method.
+// WaitForAsyncOperationCompletion mocks base method
 func (m *MockInterface) WaitForAsyncOperationCompletion(ctx context.Context, future *azure.Future, asyncOperationName string) error {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "WaitForAsyncOperationCompletion", ctx, future, asyncOperationName)
@@ -179,13 +178,13 @@ func (m *MockInterface) WaitForAsyncOperationCompletion(ctx context.Context, fut
 	return ret0
 }
 
-// WaitForAsyncOperationCompletion indicates an expected call of WaitForAsyncOperationCompletion.
+// WaitForAsyncOperationCompletion indicates an expected call of WaitForAsyncOperationCompletion
 func (mr *MockInterfaceMockRecorder) WaitForAsyncOperationCompletion(ctx, future, asyncOperationName interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "WaitForAsyncOperationCompletion", reflect.TypeOf((*MockInterface)(nil).WaitForAsyncOperationCompletion), ctx, future, asyncOperationName)
 }
 
-// WaitForAsyncOperationResult mocks base method.
+// WaitForAsyncOperationResult mocks base method
 func (m *MockInterface) WaitForAsyncOperationResult(ctx context.Context, future *azure.Future, asyncOperationName string) (*http.Response, error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "WaitForAsyncOperationResult", ctx, future, asyncOperationName)
@@ -194,13 +193,13 @@ func (m *MockInterface) WaitForAsyncOperationResult(ctx context.Context, future
 	return ret0, ret1
 }
 
-// WaitForAsyncOperationResult indicates an expected call of WaitForAsyncOperationResult.
+// WaitForAsyncOperationResult indicates an expected call of WaitForAsyncOperationResult
 func (mr *MockInterfaceMockRecorder) WaitForAsyncOperationResult(ctx, future, asyncOperationName interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "WaitForAsyncOperationResult", reflect.TypeOf((*MockInterface)(nil).WaitForAsyncOperationResult), ctx, future, asyncOperationName)
 }
 
-// SendAsync mocks base method.
+// SendAsync mocks base method
 func (m *MockInterface) SendAsync(ctx context.Context, request *http.Request) (*azure.Future, *http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "SendAsync", ctx, request)
@@ -210,13 +209,13 @@ func (m *MockInterface) SendAsync(ctx context.Context, request *http.Request) (*
 	return ret0, ret1, ret2
 }
 
-// SendAsync indicates an expected call of SendAsync.
+// SendAsync indicates an expected call of SendAsync
 func (mr *MockInterfaceMockRecorder) SendAsync(ctx, request interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "SendAsync", reflect.TypeOf((*MockInterface)(nil).SendAsync), ctx, request)
 }
 
-// PutResource mocks base method.
+// PutResource mocks base method
 func (m *MockInterface) PutResource(ctx context.Context, resourceID string, parameters interface{}) (*http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "PutResource", ctx, resourceID, parameters)
@@ -225,13 +224,13 @@ func (m *MockInterface) PutResource(ctx context.Context, resourceID string, para
 	return ret0, ret1
 }
 
-// PutResource indicates an expected call of PutResource.
+// PutResource indicates an expected call of PutResource
 func (mr *MockInterfaceMockRecorder) PutResource(ctx, resourceID, parameters interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PutResource", reflect.TypeOf((*MockInterface)(nil).PutResource), ctx, resourceID, parameters)
 }
 
-// PutResources mocks base method.
+// PutResources mocks base method
 func (m *MockInterface) PutResources(ctx context.Context, resources map[string]interface{}) map[string]*armclient.PutResourcesResponse {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "PutResources", ctx, resources)
@@ -239,13 +238,27 @@ func (m *MockInterface) PutResources(ctx context.Context, resources map[string]i
 	return ret0
 }
 
-// PutResources indicates an expected call of PutResources.
+// PutResources indicates an expected call of PutResources
 func (mr *MockInterfaceMockRecorder) PutResources(ctx, resources interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PutResources", reflect.TypeOf((*MockInterface)(nil).PutResources), ctx, resources)
 }
 
-// PutResourceWithDecorators mocks base method.
+// PutResourcesInBatches mocks base method
+func (m *MockInterface) PutResourcesInBatches(ctx context.Context, resources map[string]interface{}, batchSize int) map[string]*armclient.PutResourcesResponse {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "PutResourcesInBatches", ctx, resources, batchSize)
+	ret0, _ := ret[0].(map[string]*armclient.PutResourcesResponse)
+	return ret0
+}
+
+// PutResourcesInBatches indicates an expected call of PutResourcesInBatches
+func (mr *MockInterfaceMockRecorder) PutResourcesInBatches(ctx, resources, batchSize interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PutResourcesInBatches", reflect.TypeOf((*MockInterface)(nil).PutResourcesInBatches), ctx, resources, batchSize)
+}
+
+// PutResourceWithDecorators mocks base method
 func (m *MockInterface) PutResourceWithDecorators(ctx context.Context, resourceID string, parameters interface{}, decorators []autorest.PrepareDecorator) (*http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "PutResourceWithDecorators", ctx, resourceID, parameters, decorators)
@@ -254,13 +267,13 @@ func (m *MockInterface) PutResourceWithDecorators(ctx context.Context, resourceI
 	return ret0, ret1
 }
 
-// PutResourceWithDecorators indicates an expected call of PutResourceWithDecorators.
+// PutResourceWithDecorators indicates an expected call of PutResourceWithDecorators
 func (mr *MockInterfaceMockRecorder) PutResourceWithDecorators(ctx, resourceID, parameters, decorators interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PutResourceWithDecorators", reflect.TypeOf((*MockInterface)(nil).PutResourceWithDecorators), ctx, resourceID, parameters, decorators)
 }
 
-// PatchResource mocks base method.
+// PatchResource mocks base method
 func (m *MockInterface) PatchResource(ctx context.Context, resourceID string, parameters interface{}) (*http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "PatchResource", ctx, resourceID, parameters)
@@ -269,13 +282,13 @@ func (m *MockInterface) PatchResource(ctx context.Context, resourceID string, pa
 	return ret0, ret1
 }
 
-// PatchResource indicates an expected call of PatchResource.
+// PatchResource indicates an expected call of PatchResource
 func (mr *MockInterfaceMockRecorder) PatchResource(ctx, resourceID, parameters interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PatchResource", reflect.TypeOf((*MockInterface)(nil).PatchResource), ctx, resourceID, parameters)
 }
 
-// PatchResourceAsync mocks base method.
+// PatchResourceAsync mocks base method
 func (m *MockInterface) PatchResourceAsync(ctx context.Context, resourceID string, parameters interface{}) (*azure.Future, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "PatchResourceAsync", ctx, resourceID, parameters)
@@ -284,13 +297,13 @@ func (m *MockInterface) PatchResourceAsync(ctx context.Context, resourceID strin
 	return ret0, ret1
 }
 
-// PatchResourceAsync indicates an expected call of PatchResourceAsync.
+// PatchResourceAsync indicates an expected call of PatchResourceAsync
 func (mr *MockInterfaceMockRecorder) PatchResourceAsync(ctx, resourceID, parameters interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PatchResourceAsync", reflect.TypeOf((*MockInterface)(nil).PatchResourceAsync), ctx, resourceID, parameters)
 }
 
-// PutResourceAsync mocks base method.
+// PutResourceAsync mocks base method
 func (m *MockInterface) PutResourceAsync(ctx context.Context, resourceID string, parameters interface{}) (*azure.Future, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "PutResourceAsync", ctx, resourceID, parameters)
@@ -299,13 +312,13 @@ func (m *MockInterface) PutResourceAsync(ctx context.Context, resourceID string,
 	return ret0, ret1
 }
 
-// PutResourceAsync indicates an expected call of PutResourceAsync.
+// PutResourceAsync indicates an expected call of PutResourceAsync
 func (mr *MockInterfaceMockRecorder) PutResourceAsync(ctx, resourceID, parameters interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PutResourceAsync", reflect.TypeOf((*MockInterface)(nil).PutResourceAsync), ctx, resourceID, parameters)
 }
 
-// HeadResource mocks base method.
+// HeadResource mocks base method
 func (m *MockInterface) HeadResource(ctx context.Context, resourceID string) (*http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "HeadResource", ctx, resourceID)
@@ -314,13 +327,13 @@ func (m *MockInterface) HeadResource(ctx context.Context, resourceID string) (*h
 	return ret0, ret1
 }
 
-// HeadResource indicates an expected call of HeadResource.
+// HeadResource indicates an expected call of HeadResource
 func (mr *MockInterfaceMockRecorder) HeadResource(ctx, resourceID interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "HeadResource", reflect.TypeOf((*MockInterface)(nil).HeadResource), ctx, resourceID)
 }
 
-// GetResource mocks base method.
+// GetResource mocks base method
 func (m *MockInterface) GetResource(ctx context.Context, resourceID, expand string) (*http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "GetResource", ctx, resourceID, expand)
@@ -329,13 +342,13 @@ func (m *MockInterface) GetResource(ctx context.Context, resourceID, expand stri
 	return ret0, ret1
 }
 
-// GetResource indicates an expected call of GetResource.
+// GetResource indicates an expected call of GetResource
 func (mr *MockInterfaceMockRecorder) GetResource(ctx, resourceID, expand interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetResource", reflect.TypeOf((*MockInterface)(nil).GetResource), ctx, resourceID, expand)
 }
 
-// GetResourceWithDecorators mocks base method.
+// GetResourceWithDecorators mocks base method
 func (m *MockInterface) GetResourceWithDecorators(ctx context.Context, resourceID string, decorators []autorest.PrepareDecorator) (*http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "GetResourceWithDecorators", ctx, resourceID, decorators)
@@ -344,13 +357,13 @@ func (m *MockInterface) GetResourceWithDecorators(ctx context.Context, resourceI
 	return ret0, ret1
 }
 
-// GetResourceWithDecorators indicates an expected call of GetResourceWithDecorators.
+// GetResourceWithDecorators indicates an expected call of GetResourceWithDecorators
 func (mr *MockInterfaceMockRecorder) GetResourceWithDecorators(ctx, resourceID, decorators interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetResourceWithDecorators", reflect.TypeOf((*MockInterface)(nil).GetResourceWithDecorators), ctx, resourceID, decorators)
 }
 
-// PostResource mocks base method.
+// PostResource mocks base method
 func (m *MockInterface) PostResource(ctx context.Context, resourceID, action string, parameters interface{}) (*http.Response, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "PostResource", ctx, resourceID, action, parameters)
@@ -359,13 +372,13 @@ func (m *MockInterface) PostResource(ctx context.Context, resourceID, action str
 	return ret0, ret1
 }
 
-// PostResource indicates an expected call of PostResource.
+// PostResource indicates an expected call of PostResource
 func (mr *MockInterfaceMockRecorder) PostResource(ctx, resourceID, action, parameters interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "PostResource", reflect.TypeOf((*MockInterface)(nil).PostResource), ctx, resourceID, action, parameters)
 }
 
-// DeleteResource mocks base method.
+// DeleteResource mocks base method
 func (m *MockInterface) DeleteResource(ctx context.Context, resourceID, ifMatch string) *retry.Error {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "DeleteResource", ctx, resourceID, ifMatch)
@@ -373,13 +386,13 @@ func (m *MockInterface) DeleteResource(ctx context.Context, resourceID, ifMatch
 	return ret0
 }
 
-// DeleteResource indicates an expected call of DeleteResource.
+// DeleteResource indicates an expected call of DeleteResource
 func (mr *MockInterfaceMockRecorder) DeleteResource(ctx, resourceID, ifMatch interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "DeleteResource", reflect.TypeOf((*MockInterface)(nil).DeleteResource), ctx, resourceID, ifMatch)
 }
 
-// DeleteResourceAsync mocks base method.
+// DeleteResourceAsync mocks base method
 func (m *MockInterface) DeleteResourceAsync(ctx context.Context, resourceID, ifMatch string) (*azure.Future, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "DeleteResourceAsync", ctx, resourceID, ifMatch)
@@ -388,19 +401,19 @@ func (m *MockInterface) DeleteResourceAsync(ctx context.Context, resourceID, ifM
 	return ret0, ret1
 }
 
-// DeleteResourceAsync indicates an expected call of DeleteResourceAsync.
+// DeleteResourceAsync indicates an expected call of DeleteResourceAsync
 func (mr *MockInterfaceMockRecorder) DeleteResourceAsync(ctx, resourceID, ifMatch interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "DeleteResourceAsync", reflect.TypeOf((*MockInterface)(nil).DeleteResourceAsync), ctx, resourceID, ifMatch)
 }
 
-// CloseResponse mocks base method.
+// CloseResponse mocks base method
 func (m *MockInterface) CloseResponse(ctx context.Context, response *http.Response) {
 	m.ctrl.T.Helper()
 	m.ctrl.Call(m, "CloseResponse", ctx, response)
 }
 
-// CloseResponse indicates an expected call of CloseResponse.
+// CloseResponse indicates an expected call of CloseResponse
 func (mr *MockInterfaceMockRecorder) CloseResponse(ctx, response interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "CloseResponse", reflect.TypeOf((*MockInterface)(nil).CloseResponse), ctx, response)
diff --git a/pkg/azureclients/vmssvmclient/azure_vmssvmclient.go b/pkg/azureclients/vmssvmclient/azure_vmssvmclient.go
index f6d45bff9..38262da9a 100644
--- a/pkg/azureclients/vmssvmclient/azure_vmssvmclient.go
+++ b/pkg/azureclients/vmssvmclient/azure_vmssvmclient.go
@@ -439,7 +439,9 @@ func (page VirtualMachineScaleSetVMListResultPage) Values() []compute.VirtualMac
 }
 
 // UpdateVMs updates a list of VirtualMachineScaleSetVM from map[instanceID]compute.VirtualMachineScaleSetVM.
-func (c *Client) UpdateVMs(ctx context.Context, resourceGroupName string, VMScaleSetName string, instances map[string]compute.VirtualMachineScaleSetVM, source string) *retry.Error {
+// If the batch size > 0, it will send sync requests concurrently in batches, or it will send sync requests in sequence.
+// No matter what the batch size is, it will process the async requests concurrently in one single batch.
+func (c *Client) UpdateVMs(ctx context.Context, resourceGroupName string, VMScaleSetName string, instances map[string]compute.VirtualMachineScaleSetVM, source string, batchSize int) *retry.Error {
 	mc := metrics.NewMetricContext("vmssvm", "update_vms", resourceGroupName, c.subscriptionID, source)
 
 	// Report errors if the client is rate limited.
@@ -455,7 +457,7 @@ func (c *Client) UpdateVMs(ctx context.Context, resourceGroupName string, VMScal
 		return rerr
 	}
 
-	rerr := c.updateVMSSVMs(ctx, resourceGroupName, VMScaleSetName, instances)
+	rerr := c.updateVMSSVMs(ctx, resourceGroupName, VMScaleSetName, instances, batchSize)
 	mc.Observe(rerr)
 	if rerr != nil {
 		if rerr.IsThrottled() {
@@ -470,7 +472,7 @@ func (c *Client) UpdateVMs(ctx context.Context, resourceGroupName string, VMScal
 }
 
 // updateVMSSVMs updates a list of VirtualMachineScaleSetVM from map[instanceID]compute.VirtualMachineScaleSetVM.
-func (c *Client) updateVMSSVMs(ctx context.Context, resourceGroupName string, VMScaleSetName string, instances map[string]compute.VirtualMachineScaleSetVM) *retry.Error {
+func (c *Client) updateVMSSVMs(ctx context.Context, resourceGroupName string, VMScaleSetName string, instances map[string]compute.VirtualMachineScaleSetVM, batchSize int) *retry.Error {
 	resources := make(map[string]interface{})
 	for instanceID, parameter := range instances {
 		resourceID := armclient.GetChildResourceID(
@@ -484,7 +486,7 @@ func (c *Client) updateVMSSVMs(ctx context.Context, resourceGroupName string, VM
 		resources[resourceID] = parameter
 	}
 
-	responses := c.armClient.PutResources(ctx, resources)
+	responses := c.armClient.PutResourcesInBatches(ctx, resources, batchSize)
 	errors := make([]*retry.Error, 0)
 	for resourceID, resp := range responses {
 		if resp == nil {
diff --git a/pkg/azureclients/vmssvmclient/interface.go b/pkg/azureclients/vmssvmclient/interface.go
index e10775cb2..84adbee11 100644
--- a/pkg/azureclients/vmssvmclient/interface.go
+++ b/pkg/azureclients/vmssvmclient/interface.go
@@ -53,5 +53,5 @@ type Interface interface {
 	WaitForUpdateResult(ctx context.Context, future *azure.Future, resourceGroupName, source string) *retry.Error
 
 	// UpdateVMs updates a list of VirtualMachineScaleSetVM from map[instanceID]compute.VirtualMachineScaleSetVM.
-	UpdateVMs(ctx context.Context, resourceGroupName string, VMScaleSetName string, instances map[string]compute.VirtualMachineScaleSetVM, source string) *retry.Error
+	UpdateVMs(ctx context.Context, resourceGroupName string, VMScaleSetName string, instances map[string]compute.VirtualMachineScaleSetVM, source string, batchSize int) *retry.Error
 }
diff --git a/pkg/azureclients/vmssvmclient/mockvmssvmclient/interface.go b/pkg/azureclients/vmssvmclient/mockvmssvmclient/interface.go
index cecf71964..f98312e9e 100644
--- a/pkg/azureclients/vmssvmclient/mockvmssvmclient/interface.go
+++ b/pkg/azureclients/vmssvmclient/mockvmssvmclient/interface.go
@@ -23,38 +23,37 @@ package mockvmssvmclient
 
 import (
 	context "context"
-	reflect "reflect"
-
 	compute "github.com/Azure/azure-sdk-for-go/services/compute/mgmt/2020-12-01/compute"
 	azure "github.com/Azure/go-autorest/autorest/azure"
 	gomock "github.com/golang/mock/gomock"
+	reflect "reflect"
 	retry "sigs.k8s.io/cloud-provider-azure/pkg/retry"
 )
 
-// MockInterface is a mock of Interface interface.
+// MockInterface is a mock of Interface interface
 type MockInterface struct {
 	ctrl     *gomock.Controller
 	recorder *MockInterfaceMockRecorder
 }
 
-// MockInterfaceMockRecorder is the mock recorder for MockInterface.
+// MockInterfaceMockRecorder is the mock recorder for MockInterface
 type MockInterfaceMockRecorder struct {
 	mock *MockInterface
 }
 
-// NewMockInterface creates a new mock instance.
+// NewMockInterface creates a new mock instance
 func NewMockInterface(ctrl *gomock.Controller) *MockInterface {
 	mock := &MockInterface{ctrl: ctrl}
 	mock.recorder = &MockInterfaceMockRecorder{mock}
 	return mock
 }
 
-// EXPECT returns an object that allows the caller to indicate expected use.
+// EXPECT returns an object that allows the caller to indicate expected use
 func (m *MockInterface) EXPECT() *MockInterfaceMockRecorder {
 	return m.recorder
 }
 
-// Get mocks base method.
+// Get mocks base method
 func (m *MockInterface) Get(ctx context.Context, resourceGroupName, VMScaleSetName, instanceID string, expand compute.InstanceViewTypes) (compute.VirtualMachineScaleSetVM, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "Get", ctx, resourceGroupName, VMScaleSetName, instanceID, expand)
@@ -63,13 +62,13 @@ func (m *MockInterface) Get(ctx context.Context, resourceGroupName, VMScaleSetNa
 	return ret0, ret1
 }
 
-// Get indicates an expected call of Get.
+// Get indicates an expected call of Get
 func (mr *MockInterfaceMockRecorder) Get(ctx, resourceGroupName, VMScaleSetName, instanceID, expand interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Get", reflect.TypeOf((*MockInterface)(nil).Get), ctx, resourceGroupName, VMScaleSetName, instanceID, expand)
 }
 
-// List mocks base method.
+// List mocks base method
 func (m *MockInterface) List(ctx context.Context, resourceGroupName, virtualMachineScaleSetName, expand string) ([]compute.VirtualMachineScaleSetVM, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "List", ctx, resourceGroupName, virtualMachineScaleSetName, expand)
@@ -78,13 +77,13 @@ func (m *MockInterface) List(ctx context.Context, resourceGroupName, virtualMach
 	return ret0, ret1
 }
 
-// List indicates an expected call of List.
+// List indicates an expected call of List
 func (mr *MockInterfaceMockRecorder) List(ctx, resourceGroupName, virtualMachineScaleSetName, expand interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "List", reflect.TypeOf((*MockInterface)(nil).List), ctx, resourceGroupName, virtualMachineScaleSetName, expand)
 }
 
-// Update mocks base method.
+// Update mocks base method
 func (m *MockInterface) Update(ctx context.Context, resourceGroupName, VMScaleSetName, instanceID string, parameters compute.VirtualMachineScaleSetVM, source string) *retry.Error {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "Update", ctx, resourceGroupName, VMScaleSetName, instanceID, parameters, source)
@@ -92,13 +91,13 @@ func (m *MockInterface) Update(ctx context.Context, resourceGroupName, VMScaleSe
 	return ret0
 }
 
-// Update indicates an expected call of Update.
+// Update indicates an expected call of Update
 func (mr *MockInterfaceMockRecorder) Update(ctx, resourceGroupName, VMScaleSetName, instanceID, parameters, source interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Update", reflect.TypeOf((*MockInterface)(nil).Update), ctx, resourceGroupName, VMScaleSetName, instanceID, parameters, source)
 }
 
-// UpdateAsync mocks base method.
+// UpdateAsync mocks base method
 func (m *MockInterface) UpdateAsync(ctx context.Context, resourceGroupName, VMScaleSetName, instanceID string, parameters compute.VirtualMachineScaleSetVM, source string) (*azure.Future, *retry.Error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "UpdateAsync", ctx, resourceGroupName, VMScaleSetName, instanceID, parameters, source)
@@ -107,13 +106,13 @@ func (m *MockInterface) UpdateAsync(ctx context.Context, resourceGroupName, VMSc
 	return ret0, ret1
 }
 
-// UpdateAsync indicates an expected call of UpdateAsync.
+// UpdateAsync indicates an expected call of UpdateAsync
 func (mr *MockInterfaceMockRecorder) UpdateAsync(ctx, resourceGroupName, VMScaleSetName, instanceID, parameters, source interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "UpdateAsync", reflect.TypeOf((*MockInterface)(nil).UpdateAsync), ctx, resourceGroupName, VMScaleSetName, instanceID, parameters, source)
 }
 
-// WaitForUpdateResult mocks base method.
+// WaitForUpdateResult mocks base method
 func (m *MockInterface) WaitForUpdateResult(ctx context.Context, future *azure.Future, resourceGroupName, source string) *retry.Error {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "WaitForUpdateResult", ctx, future, resourceGroupName, source)
@@ -121,22 +120,22 @@ func (m *MockInterface) WaitForUpdateResult(ctx context.Context, future *azure.F
 	return ret0
 }
 
-// WaitForUpdateResult indicates an expected call of WaitForUpdateResult.
+// WaitForUpdateResult indicates an expected call of WaitForUpdateResult
 func (mr *MockInterfaceMockRecorder) WaitForUpdateResult(ctx, future, resourceGroupName, source interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "WaitForUpdateResult", reflect.TypeOf((*MockInterface)(nil).WaitForUpdateResult), ctx, future, resourceGroupName, source)
 }
 
-// UpdateVMs mocks base method.
-func (m *MockInterface) UpdateVMs(ctx context.Context, resourceGroupName, VMScaleSetName string, instances map[string]compute.VirtualMachineScaleSetVM, source string) *retry.Error {
+// UpdateVMs mocks base method
+func (m *MockInterface) UpdateVMs(ctx context.Context, resourceGroupName, VMScaleSetName string, instances map[string]compute.VirtualMachineScaleSetVM, source string, batchSize int) *retry.Error {
 	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "UpdateVMs", ctx, resourceGroupName, VMScaleSetName, instances, source)
+	ret := m.ctrl.Call(m, "UpdateVMs", ctx, resourceGroupName, VMScaleSetName, instances, source, batchSize)
 	ret0, _ := ret[0].(*retry.Error)
 	return ret0
 }
 
-// UpdateVMs indicates an expected call of UpdateVMs.
-func (mr *MockInterfaceMockRecorder) UpdateVMs(ctx, resourceGroupName, VMScaleSetName, instances, source interface{}) *gomock.Call {
+// UpdateVMs indicates an expected call of UpdateVMs
+func (mr *MockInterfaceMockRecorder) UpdateVMs(ctx, resourceGroupName, VMScaleSetName, instances, source, batchSize interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "UpdateVMs", reflect.TypeOf((*MockInterface)(nil).UpdateVMs), ctx, resourceGroupName, VMScaleSetName, instances, source)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "UpdateVMs", reflect.TypeOf((*MockInterface)(nil).UpdateVMs), ctx, resourceGroupName, VMScaleSetName, instances, source, batchSize)
 }
diff --git a/pkg/provider/azure.go b/pkg/provider/azure.go
index 32708a8e6..c5e838f5d 100644
--- a/pkg/provider/azure.go
+++ b/pkg/provider/azure.go
@@ -232,6 +232,9 @@ type Config struct {
 	RouteUpdateWaitingInSeconds int `json:"routeUpdateWaitingInSeconds,omitempty" yaml:"routeUpdateWaitingInSeconds,omitempty"`
 	// The user agent for Azure customer usage attribution
 	UserAgent string `json:"userAgent,omitempty" yaml:"userAgent,omitempty"`
+	// PutVMSSVMBatchSize defines how many requests the client send concurrently when putting the VMSS VMs.
+	// If it is smaller than or equal to zero, the request will be sent one by one in sequence (default).
+	PutVMSSVMBatchSize int `json:"putVMSSVMBatchSize" yaml:"putVMSSVMBatchSize"`
 }
 
 type InitSecretConfig struct {
@@ -601,6 +604,10 @@ func (az *Cloud) InitializeCloudFromConfig(config *Config, fromSecret, callFromC
 	return nil
 }
 
+func (az *Cloud) getPutVMSSVMBatchSize() int {
+	return az.PutVMSSVMBatchSize
+}
+
 func (az *Cloud) initCaches() (err error) {
 	az.vmCache, err = az.newVMCache()
 	if err != nil {
diff --git a/pkg/provider/azure_vmss.go b/pkg/provider/azure_vmss.go
index 58d1f4669..b528f7555 100644
--- a/pkg/provider/azure_vmss.go
+++ b/pkg/provider/azure_vmss.go
@@ -1318,7 +1318,7 @@ func (ss *ScaleSet) EnsureHostsInPool(service *v1.Service, nodes []*v1.Node, bac
 			ctx, cancel := getContextWithCancel()
 			defer cancel()
 			klog.V(2).Infof("EnsureHostInPool begins to UpdateVMs for VMSS(%s, %s) with new backendPoolID %s", meta.resourceGroup, meta.vmssName, backendPoolID)
-			rerr := ss.VirtualMachineScaleSetVMsClient.UpdateVMs(ctx, meta.resourceGroup, meta.vmssName, update, "network_update")
+			rerr := ss.VirtualMachineScaleSetVMsClient.UpdateVMs(ctx, meta.resourceGroup, meta.vmssName, update, "network_update", ss.getPutVMSSVMBatchSize())
 			if rerr != nil {
 				klog.Errorf("EnsureHostInPool UpdateVMs for VMSS(%s, %s) failed with error %v", meta.resourceGroup, meta.vmssName, rerr.Error())
 				return rerr.Error()
@@ -1580,7 +1580,7 @@ func (ss *ScaleSet) EnsureBackendPoolDeleted(service *v1.Service, backendPoolID,
 			ctx, cancel := getContextWithCancel()
 			defer cancel()
 			klog.V(2).Infof("EnsureBackendPoolDeleted begins to UpdateVMs for VMSS(%s, %s) with backendPoolID %s", meta.resourceGroup, meta.vmssName, backendPoolID)
-			rerr := ss.VirtualMachineScaleSetVMsClient.UpdateVMs(ctx, meta.resourceGroup, meta.vmssName, update, "network_update")
+			rerr := ss.VirtualMachineScaleSetVMsClient.UpdateVMs(ctx, meta.resourceGroup, meta.vmssName, update, "network_update", ss.getPutVMSSVMBatchSize())
 			if rerr != nil {
 				klog.Errorf("EnsureBackendPoolDeleted UpdateVMs for VMSS(%s, %s) failed with error %v", meta.resourceGroup, meta.vmssName, rerr.Error())
 				return rerr.Error()


Test patch:
diff --git a/pkg/azureclients/armclient/azure_armclient_test.go b/pkg/azureclients/armclient/azure_armclient_test.go
index 9001c654a..4a16d8797 100644
--- a/pkg/azureclients/armclient/azure_armclient_test.go
+++ b/pkg/azureclients/armclient/azure_armclient_test.go
@@ -23,6 +23,7 @@ import (
 	"net/http"
 	"net/http/cookiejar"
 	"net/http/httptest"
+	"sync"
 	"testing"
 	"time"
 
@@ -340,6 +341,26 @@ func TestPutResource(t *testing.T) {
 }
 
 func TestPutResources(t *testing.T) {
+	total := 0
+	server := getTestServer(t, &total)
+
+	backoff := &retry.Backoff{Steps: 1}
+	armClient := New(nil, server.URL, "test", "2019-01-01", "eastus", backoff)
+	armClient.client.RetryDuration = time.Millisecond * 1
+
+	ctx := context.Background()
+	resources := map[string]interface{}{
+		"/id/1": nil,
+		"/id/2": nil,
+	}
+	responses := armClient.PutResources(ctx, nil)
+	assert.Nil(t, responses)
+	responses = armClient.PutResources(ctx, resources)
+	assert.NotNil(t, responses)
+	assert.Equal(t, 3, total)
+}
+
+func getTestServer(t *testing.T, counter *int) *httptest.Server {
 	serverFuncs := []func(rw http.ResponseWriter, req *http.Request){
 		func(rw http.ResponseWriter, req *http.Request) {
 			assert.Equal(t, "PUT", req.Method)
@@ -369,30 +390,81 @@ func TestPutResources(t *testing.T) {
 		},
 	}
 
-	i, total := 0, 0
-	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	i := 0
+	var l sync.Mutex
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l.Lock()
 		serverFuncs[i](w, r)
 		i++
 		if i > 3 {
 			i = 3
 		}
-		total++
+		*counter++
+		l.Unlock()
 	}))
+}
 
-	backoff := &retry.Backoff{Steps: 1}
-	armClient := New(nil, server.URL, "test", "2019-01-01", "eastus", backoff)
-	armClient.client.RetryDuration = time.Millisecond * 1
-
-	ctx := context.Background()
-	resources := map[string]interface{}{
-		"/id/1": nil,
-		"/id/2": nil,
+func TestPutResourcesInBatches(t *testing.T) {
+	for _, testCase := range []struct {
+		description                  string
+		resources                    map[string]interface{}
+		batchSize, expectedCallTimes int
+	}{
+		{
+			description: "",
+			resources: map[string]interface{}{
+				"/id/1": nil,
+				"/id/2": nil,
+			},
+			batchSize:         2,
+			expectedCallTimes: 3,
+		},
+		{
+			description: "",
+			resources: map[string]interface{}{
+				"/id/1": nil,
+				"/id/2": nil,
+			},
+			batchSize:         1,
+			expectedCallTimes: 3,
+		},
+		{
+			description: "",
+			resources:   nil,
+		},
+		{
+			description: "PutResourcesInBatches should set the batch size to the length of the resources if the batch size is larger than it",
+			resources: map[string]interface{}{
+				"/id/1": nil,
+				"/id/2": nil,
+			},
+			batchSize:         10,
+			expectedCallTimes: 3,
+		},
+		{
+			description: "PutResourcesInBatches should call PutResources if the batch size is smaller than or equal to zero",
+			resources: map[string]interface{}{
+				"/id/1": nil,
+				"/id/2": nil,
+			},
+			expectedCallTimes: 3,
+		},
+	} {
+		t.Run(testCase.description, func(t *testing.T) {
+			total := 0
+			server := getTestServer(t, &total)
+
+			backoff := &retry.Backoff{Steps: 1}
+			armClient := New(nil, server.URL, "test", "2019-01-01", "eastus", backoff)
+			armClient.client.RetryDuration = time.Millisecond * 1
+
+			ctx := context.Background()
+			responses := armClient.PutResourcesInBatches(ctx, testCase.resources, testCase.batchSize)
+			assert.Equal(t, testCase.resources == nil, responses == nil)
+			assert.Equal(t, testCase.expectedCallTimes, total)
+		})
 	}
-	responses := armClient.PutResources(ctx, nil)
-	assert.Nil(t, responses)
-	responses = armClient.PutResources(ctx, resources)
-	assert.NotNil(t, responses)
-	assert.Equal(t, 3, total)
+
 }
 
 func TestPutResourceAsync(t *testing.T) {
diff --git a/pkg/azureclients/vmssvmclient/azure_vmssvmclient_test.go b/pkg/azureclients/vmssvmclient/azure_vmssvmclient_test.go
index 3a0406204..b30bfce7d 100644
--- a/pkg/azureclients/vmssvmclient/azure_vmssvmclient_test.go
+++ b/pkg/azureclients/vmssvmclient/azure_vmssvmclient_test.go
@@ -650,11 +650,11 @@ func TestUpdateVMs(t *testing.T) {
 	}
 
 	armClient := mockarmclient.NewMockInterface(ctrl)
-	armClient.EXPECT().PutResources(gomock.Any(), testvmssVMs).Return(responses).Times(1)
+	armClient.EXPECT().PutResourcesInBatches(gomock.Any(), testvmssVMs, 0).Return(responses).Times(1)
 	armClient.EXPECT().CloseResponse(gomock.Any(), gomock.Any()).Times(2)
 
 	vmssvmClient := getTestVMSSVMClient(armClient)
-	rerr := vmssvmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test")
+	rerr := vmssvmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test", 0)
 	assert.Nil(t, rerr)
 }
 
@@ -679,11 +679,11 @@ func TestUpdateVMsWithUpdateVMsResponderError(t *testing.T) {
 		},
 	}
 	armClient := mockarmclient.NewMockInterface(ctrl)
-	armClient.EXPECT().PutResources(gomock.Any(), testvmssVMs).Return(responses).Times(1)
+	armClient.EXPECT().PutResourcesInBatches(gomock.Any(), testvmssVMs, 0).Return(responses).Times(1)
 	armClient.EXPECT().CloseResponse(gomock.Any(), gomock.Any()).Times(1)
 
 	vmssvmClient := getTestVMSSVMClient(armClient)
-	rerr := vmssvmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test")
+	rerr := vmssvmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test", 0)
 	assert.NotNil(t, rerr)
 }
 
@@ -699,7 +699,7 @@ func TestUpdateVMsNeverRateLimiter(t *testing.T) {
 
 	armClient := mockarmclient.NewMockInterface(ctrl)
 	vmssvmClient := getTestVMSSVMClientWithNeverRateLimiter(armClient)
-	rerr := vmssvmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test")
+	rerr := vmssvmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test", 0)
 	assert.NotNil(t, rerr)
 	assert.Equal(t, vmssvmUpdateVMsErr, rerr)
 }
@@ -717,7 +717,7 @@ func TestUpdateVMsRetryAfterReader(t *testing.T) {
 
 	armClient := mockarmclient.NewMockInterface(ctrl)
 	vmClient := getTestVMSSVMClientWithRetryAfterReader(armClient)
-	rerr := vmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test")
+	rerr := vmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test", 0)
 	assert.NotNil(t, rerr)
 	assert.Equal(t, vmssvmUpdateVMsErr, rerr)
 }
@@ -750,11 +750,11 @@ func TestUpdateVMsThrottle(t *testing.T) {
 	}
 
 	armClient := mockarmclient.NewMockInterface(ctrl)
-	armClient.EXPECT().PutResources(gomock.Any(), testvmssVMs).Return(responses).Times(1)
+	armClient.EXPECT().PutResourcesInBatches(gomock.Any(), testvmssVMs, 0).Return(responses).Times(1)
 	armClient.EXPECT().CloseResponse(gomock.Any(), gomock.Any()).Times(1)
 
 	vmssvmClient := getTestVMSSVMClient(armClient)
-	rerr := vmssvmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test")
+	rerr := vmssvmClient.UpdateVMs(context.TODO(), "rg", "vmss1", instances, "test", 0)
 	assert.NotNil(t, rerr)
 	assert.EqualError(t, throttleErr.Error(), rerr.RawError.Error())
 }
diff --git a/pkg/provider/azure_vmss_test.go b/pkg/provider/azure_vmss_test.go
index 618108e49..b0f19d00b 100644
--- a/pkg/provider/azure_vmss_test.go
+++ b/pkg/provider/azure_vmss_test.go
@@ -2190,7 +2190,7 @@ func TestEnsureHostsInPool(t *testing.T) {
 		expectedVMSSVMs, _, _ := buildTestVirtualMachineEnv(ss.cloud, testVMSSName, "", 0, []string{"vmss-vm-000000", "vmss-vm-000001", "vmss-vm-000002"}, "", false)
 		mockVMSSVMClient := ss.cloud.VirtualMachineScaleSetVMsClient.(*mockvmssvmclient.MockInterface)
 		mockVMSSVMClient.EXPECT().List(gomock.Any(), ss.ResourceGroup, testVMSSName, gomock.Any()).Return(expectedVMSSVMs, nil).AnyTimes()
-		mockVMSSVMClient.EXPECT().UpdateVMs(gomock.Any(), ss.ResourceGroup, testVMSSName, gomock.Any(), gomock.Any()).Return(nil).Times(test.expectedVMSSVMPutTimes)
+		mockVMSSVMClient.EXPECT().UpdateVMs(gomock.Any(), ss.ResourceGroup, testVMSSName, gomock.Any(), gomock.Any(), gomock.Any()).Return(nil).Times(test.expectedVMSSVMPutTimes)
 
 		mockVMClient := ss.cloud.VirtualMachinesClient.(*mockvmclient.MockInterface)
 		mockVMClient.EXPECT().List(gomock.Any(), gomock.Any()).Return(nil, nil).AnyTimes()
@@ -2481,7 +2481,7 @@ func TestEnsureBackendPoolDeleted(t *testing.T) {
 		expectedVMSSVMs, _, _ := buildTestVirtualMachineEnv(ss.cloud, testVMSSName, "", 0, []string{"vmss-vm-000000", "vmss-vm-000001", "vmss-vm-000002"}, "", false)
 		mockVMSSVMClient := ss.cloud.VirtualMachineScaleSetVMsClient.(*mockvmssvmclient.MockInterface)
 		mockVMSSVMClient.EXPECT().List(gomock.Any(), ss.ResourceGroup, testVMSSName, gomock.Any()).Return(expectedVMSSVMs, nil).AnyTimes()
-		mockVMSSVMClient.EXPECT().UpdateVMs(gomock.Any(), ss.ResourceGroup, testVMSSName, gomock.Any(), gomock.Any()).Return(test.vmClientErr).Times(test.expectedVMSSVMPutTimes)
+		mockVMSSVMClient.EXPECT().UpdateVMs(gomock.Any(), ss.ResourceGroup, testVMSSName, gomock.Any(), gomock.Any(), gomock.Any()).Return(test.vmClientErr).Times(test.expectedVMSSVMPutTimes)
 
 		err = ss.EnsureBackendPoolDeleted(&v1.Service{}, test.backendpoolID, testVMSSName, test.backendAddressPools, true)
 		assert.Equal(t, test.expectedErr, err != nil, test.description+", but an error occurs")
@@ -2554,7 +2554,7 @@ func TestEnsureBackendPoolDeletedConcurrently(t *testing.T) {
 	mockVMSSVMClient.EXPECT().List(gomock.Any(), "rg1", "vmss-0", gomock.Any()).Return(nil, nil).AnyTimes()
 	mockVMSSVMClient.EXPECT().List(gomock.Any(), ss.ResourceGroup, "vmss-0", gomock.Any()).Return(expectedVMSSVMsOfVMSS0, nil).AnyTimes()
 	mockVMSSVMClient.EXPECT().List(gomock.Any(), ss.ResourceGroup, "vmss-1", gomock.Any()).Return(expectedVMSSVMsOfVMSS1, nil).AnyTimes()
-	mockVMSSVMClient.EXPECT().UpdateVMs(gomock.Any(), ss.ResourceGroup, gomock.Any(), gomock.Any(), gomock.Any()).Return(nil).Times(2)
+	mockVMSSVMClient.EXPECT().UpdateVMs(gomock.Any(), ss.ResourceGroup, gomock.Any(), gomock.Any(), gomock.Any(), gomock.Any()).Return(nil).Times(2)
 
 	backendpoolAddressIDs := []string{testLBBackendpoolID0, testLBBackendpoolID1, testLBBackendpoolID2}
 	testVMSSNames := []string{"vmss-0", "vmss-1", "vmss-2"}