diff --git a/jest.config.js b/jest.config.js
index 829b8cb4..d130bfea 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -5,7 +5,7 @@ module.exports = {
   moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
   testTimeout: 60000,
   // because user will cause other test fail, but we still have user spec
-  coveragePathIgnorePatterns: ['/milvus/User.ts'],
+  coveragePathIgnorePatterns: ['dist'],
   testPathIgnorePatterns: ['cloud.spec.ts', 'serverless.spec.ts'], // add this line
   testEnvironmentOptions: {
     NODE_ENV: 'production',
diff --git a/milvus/MilvusClient.ts b/milvus/MilvusClient.ts
index aaafa1e2..5903ab43 100644
--- a/milvus/MilvusClient.ts
+++ b/milvus/MilvusClient.ts
@@ -60,8 +60,14 @@ export class MilvusClient extends GRPCClient {
     logger.debug(
       `new client initialized, version: ${MilvusClient.sdkInfo.version} `
     );
-    // connect();
-    this.connect(MilvusClient.sdkInfo.version);
+
+    // If the configOrAddress is a string (i.e., the server's address), or if the configOrAddress object does not have the __SKIP_CONNECT__ property set to true, then establish a connection to the Milvus server using the current SDK version.
+    if (
+      typeof configOrAddress === 'string' ||
+      !(configOrAddress as ClientConfig).__SKIP_CONNECT__
+    ) {
+      this.connect(MilvusClient.sdkInfo.version);
+    }
   }
 
   // High level API: align with pymilvus
diff --git a/milvus/const/client.ts b/milvus/const/client.ts
index f6e39bac..56073f7a 100644
--- a/milvus/const/client.ts
+++ b/milvus/const/client.ts
@@ -6,9 +6,10 @@ export enum METADATA {
 
 export enum CONNECT_STATUS {
   NOT_CONNECTED,
-  CONNECTING,
-  CONNECTED,
+  CONNECTING = 0, // GRPC channel state connecting
+  CONNECTED = 1, // GRPC channel state ready
   UNIMPLEMENTED,
+  SHUTDOWN = 5, // GRPC channel state shutdown
 }
 
 export enum TLS_MODE {
diff --git a/milvus/const/defaults.ts b/milvus/const/defaults.ts
index fd9dbf1f..65b36348 100644
--- a/milvus/const/defaults.ts
+++ b/milvus/const/defaults.ts
@@ -16,3 +16,6 @@ export const DEFAULT_DYNAMIC_FIELD = '$meta';
 export const DEFAULT_COUNT_QUERY_STRING = 'count(*)';
 export const DEFAULT_HTTP_TIMEOUT = 60000; // 60s
 export const DEFAULT_HTTP_ENDPOINT_VERSION = 'v1'; // api version, default v1
+
+export const DEFAULT_POOL_MAX = 10; // default max pool client number
+export const DEFAULT_POOL_MIN = 2; // default min pool client number
diff --git a/milvus/grpc/BaseClient.ts b/milvus/grpc/BaseClient.ts
index e4bcd65b..2a3b3fe4 100644
--- a/milvus/grpc/BaseClient.ts
+++ b/milvus/grpc/BaseClient.ts
@@ -1,7 +1,14 @@
 import path from 'path';
 import crypto from 'crypto';
 import protobuf, { Root, Type } from 'protobufjs';
-import { Client, ChannelOptions } from '@grpc/grpc-js';
+import { readFileSync } from 'fs';
+import {
+  Client,
+  ChannelOptions,
+  credentials,
+  ChannelCredentials,
+} from '@grpc/grpc-js';
+import { Pool } from 'generic-pool';
 import {
   ERROR_REASONS,
   ClientConfig,
@@ -26,18 +33,36 @@ const schemaProtoPath = path.resolve(
  * Base gRPC client, setup all configuration here
  */
 export class BaseClient {
+  // channel pool
+  public channelPool!: Pool<Client>;
   // Client ID
-  clientId: string = `${crypto.randomUUID()}`;
+  public clientId: string = `${crypto.randomUUID()}`;
   // flags to indicate that if the connection is established and its state
-  connectStatus = CONNECT_STATUS.NOT_CONNECTED;
-  connectPromise = Promise.resolve();
-  // metadata
-  protected metadata: Map<string, string> = new Map<string, string>();
-  // The path to the Milvus protobuf file.
-  protected protoFilePath = {
+  public connectStatus = CONNECT_STATUS.NOT_CONNECTED;
+  // connection promise
+  public connectPromise = Promise.resolve();
+  // TLS mode, by default it is disabled
+  public readonly tlsMode: TLS_MODE = TLS_MODE.DISABLED;
+  // The client configuration.
+  public readonly config: ClientConfig;
+  // grpc options
+  public readonly channelOptions: ChannelOptions;
+  // server info
+  public serverInfo: ServerInfo = {};
+  // // The gRPC client instance.
+  // public client!: Promise<Client>;
+  // The timeout for connecting to the Milvus service.
+  public timeout: number = DEFAULT_CONNECT_TIMEOUT;
+  // The path to the Milvus protobuf file, user can define it from clientConfig
+  public protoFilePath = {
     milvus: milvusProtoPath,
     schema: schemaProtoPath,
   };
+
+  // ChannelCredentials object used for authenticating the client on the gRPC channel.
+  protected creds!: ChannelCredentials;
+  // global metadata, send each grpc request with it
+  protected metadata: Map<string, string> = new Map<string, string>();
   // The protobuf schema.
   protected schemaProto: Root;
   // The Milvus protobuf.
@@ -46,7 +71,6 @@ export class BaseClient {
   protected collectionSchemaType: Type;
   // The milvus field schema Type
   protected fieldSchemaType: Type;
-
   // milvus proto
   protected readonly protoInternalPath = {
     serviceName: 'milvus.proto.milvus.MilvusService',
@@ -54,19 +78,6 @@ export class BaseClient {
     fieldSchema: 'milvus.proto.schema.FieldSchema',
   };
 
-  // TLS mode, by default it is disabled
-  public readonly tlsMode: TLS_MODE = TLS_MODE.DISABLED;
-  // The client configuration.
-  public readonly config: ClientConfig;
-  // grpc options
-  public readonly channelOptions: ChannelOptions;
-  // server info
-  public serverInfo: ServerInfo = {};
-  // The gRPC client instance.
-  public client: Client | undefined;
-  // The timeout for connecting to the Milvus service.
-  public timeout: number = DEFAULT_CONNECT_TIMEOUT;
-
   /**
    * Sets up the configuration object for the gRPC client.
    *
@@ -163,6 +174,51 @@ export class BaseClient {
         this.config.tls.serverName;
     }
 
+    // Switch based on the TLS mode
+    switch (this.tlsMode) {
+      case TLS_MODE.ONE_WAY:
+        // Create SSL credentials with empty parameters for one-way authentication
+        this.creds = credentials.createSsl();
+        break;
+      case TLS_MODE.TWO_WAY:
+        // Extract paths for root certificate, private key, certificate chain, and verify options from the client configuration
+        const { rootCertPath, privateKeyPath, certChainPath, verifyOptions } =
+          this.config.tls!;
+
+        // Initialize buffers for root certificate, private key, and certificate chain
+        let rootCertBuff: Buffer | null = null;
+        let privateKeyBuff: Buffer | null = null;
+        let certChainBuff: Buffer | null = null;
+
+        // Read root certificate file if path is provided
+        if (rootCertPath) {
+          rootCertBuff = readFileSync(rootCertPath);
+        }
+
+        // Read private key file if path is provided
+        if (privateKeyPath) {
+          privateKeyBuff = readFileSync(privateKeyPath);
+        }
+
+        // Read certificate chain file if path is provided
+        if (certChainPath) {
+          certChainBuff = readFileSync(certChainPath);
+        }
+
+        // Create SSL credentials with the read files and verify options for two-way authentication
+        this.creds = credentials.createSsl(
+          rootCertBuff,
+          privateKeyBuff,
+          certChainBuff,
+          verifyOptions
+        );
+        break;
+      default:
+        // Create insecure credentials if no TLS mode is specified
+        this.creds = credentials.createInsecure();
+        break;
+    }
+
     // Set up the timeout for connecting to the Milvus service.
     this.timeout =
       typeof config.timeout === 'string'
diff --git a/milvus/grpc/Collection.ts b/milvus/grpc/Collection.ts
index f27ad80d..30068471 100644
--- a/milvus/grpc/Collection.ts
+++ b/milvus/grpc/Collection.ts
@@ -153,7 +153,7 @@ export class Collection extends Database {
 
     // Call the promisify function to create the collection.
     const createPromise = await promisify(
-      this.client,
+      this.channelPool,
       'CreateCollection',
       {
         ...data,
@@ -201,7 +201,7 @@ export class Collection extends Database {
 
     // avoid to call describe collection, because it has cache
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'DescribeCollection',
       data,
       data.timeout || this.timeout
@@ -242,7 +242,7 @@ export class Collection extends Database {
     data?: ShowCollectionsReq
   ): Promise<ShowCollectionsResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'ShowCollections',
       {
         type: data ? data.type : ShowCollectionsType.All,
@@ -290,7 +290,7 @@ export class Collection extends Database {
   async alterCollection(data: AlterCollectionReq): Promise<ResStatus> {
     checkCollectionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'AlterCollection',
       {
         collection_name: data.collection_name,
@@ -346,7 +346,7 @@ export class Collection extends Database {
 
     // get new data
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DescribeCollection',
       data,
       data.timeout || this.timeout
@@ -391,7 +391,7 @@ export class Collection extends Database {
     checkCollectionName(data);
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'GetCollectionStatistics',
       data,
       data.timeout || this.timeout
@@ -432,7 +432,7 @@ export class Collection extends Database {
     checkCollectionName(data);
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'LoadCollection',
       data,
       data.timeout || this.timeout
@@ -470,7 +470,7 @@ export class Collection extends Database {
     checkCollectionName(data);
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'LoadCollection',
       data,
       data.timeout || this.timeout
@@ -529,7 +529,7 @@ export class Collection extends Database {
     checkCollectionName(data);
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'ReleaseCollection',
       data,
       data.timeout || this.timeout
@@ -564,7 +564,7 @@ export class Collection extends Database {
    */
   async renameCollection(data: RenameCollectionReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'RenameCollection',
       {
         oldName: data.collection_name,
@@ -602,7 +602,7 @@ export class Collection extends Database {
     checkCollectionName(data);
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DropCollection',
       data,
       data.timeout || this.timeout
@@ -649,7 +649,7 @@ export class Collection extends Database {
       throw new Error(ERROR_REASONS.ALIAS_NAME_IS_REQUIRED);
     }
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'CreateAlias',
       data,
       data.timeout || this.timeout
@@ -688,7 +688,7 @@ export class Collection extends Database {
       throw new Error(ERROR_REASONS.ALIAS_NAME_IS_REQUIRED);
     }
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DropAlias',
       data,
       data.timeout || this.timeout
@@ -728,7 +728,7 @@ export class Collection extends Database {
       throw new Error(ERROR_REASONS.ALIAS_NAME_IS_REQUIRED);
     }
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'AlterAlias',
       data,
       data.timeout || this.timeout
@@ -763,7 +763,7 @@ export class Collection extends Database {
     checkCollectionName(data);
     const collectionInfo = await this.describeCollection(data);
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'ManualCompaction',
       {
         collectionID: collectionInfo.collectionID,
@@ -803,7 +803,7 @@ export class Collection extends Database {
       throw new Error(ERROR_REASONS.COMPACTION_ID_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'GetCompactionState',
       data,
       data.timeout || this.timeout
@@ -841,7 +841,7 @@ export class Collection extends Database {
       throw new Error(ERROR_REASONS.COMPACTION_ID_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'GetCompactionStateWithPlans',
       data,
       data.timeout || this.timeout
@@ -894,7 +894,7 @@ export class Collection extends Database {
       throw new Error(ERROR_REASONS.COLLECTION_ID_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'GetReplicas',
       data,
       data.timeout || this.timeout
@@ -935,7 +935,7 @@ export class Collection extends Database {
       throw new Error(ERROR_REASONS.COLLECTION_NAME_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'GetLoadingProgress',
       data,
       data.timeout || this.timeout
@@ -973,7 +973,7 @@ export class Collection extends Database {
       throw new Error(ERROR_REASONS.COLLECTION_NAME_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'GetLoadState',
       data,
       data.timeout || this.timeout
diff --git a/milvus/grpc/Data.ts b/milvus/grpc/Data.ts
index 5a94a3c5..cb6cd775 100644
--- a/milvus/grpc/Data.ts
+++ b/milvus/grpc/Data.ts
@@ -259,7 +259,7 @@ export class Data extends Collection {
     const timeout = typeof data.timeout === 'undefined' ? 0 : data.timeout;
     // execute Insert
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       upsert ? 'Upsert' : 'Insert',
       params,
       timeout
@@ -310,7 +310,7 @@ export class Data extends Collection {
     data.expr = data.filter || data.expr;
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'Delete',
       data,
       data.timeout || this.timeout
@@ -487,7 +487,7 @@ export class Data extends Collection {
       ).finish();
 
       const promise: SearchRes = await promisify(
-        this.client,
+        this.channelPool,
         'Search',
         {
           collection_name: data.collection_name,
@@ -627,7 +627,7 @@ export class Data extends Collection {
       throw new Error(ERROR_REASONS.COLLECTION_NAME_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'Flush',
       data,
       data.timeout || this.timeout
@@ -669,7 +669,7 @@ export class Data extends Collection {
     }
     // copy flushed collection names
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'Flush',
       data,
       data.timeout || this.timeout
@@ -740,7 +740,7 @@ export class Data extends Collection {
 
     // Execute the query and get the results
     const promise: QueryRes = await promisify(
-      this.client,
+      this.channelPool,
       'Query',
       {
         ...data,
@@ -871,7 +871,7 @@ export class Data extends Collection {
       throw new Error(ERROR_REASONS.GET_METRIC_CHECK_PARAMS);
     }
     const res: GetMetricsResponse = await promisify(
-      this.client,
+      this.channelPool,
       'GetMetrics',
       {
         request: JSON.stringify(data.request),
@@ -914,7 +914,7 @@ export class Data extends Collection {
       throw new Error(ERROR_REASONS.GET_FLUSH_STATE_CHECK_PARAMS);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'GetFlushState',
       data,
       data.timeout || this.timeout
@@ -954,7 +954,7 @@ export class Data extends Collection {
       throw new Error(ERROR_REASONS.LOAD_BALANCE_CHECK_PARAMS);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'LoadBalance',
       data,
       data.timeout || this.timeout
@@ -994,7 +994,7 @@ export class Data extends Collection {
       throw new Error(ERROR_REASONS.COLLECTION_NAME_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'GetQuerySegmentInfo',
       data,
       data.timeout || this.timeout
@@ -1034,7 +1034,7 @@ export class Data extends Collection {
       throw new Error(ERROR_REASONS.COLLECTION_NAME_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'GetPersistentSegmentInfo',
       data,
       data.timeout || this.timeout
@@ -1078,7 +1078,7 @@ export class Data extends Collection {
       throw new Error(ERROR_REASONS.IMPORT_FILE_CHECK);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'Import',
       {
         ...data,
@@ -1126,7 +1126,7 @@ export class Data extends Collection {
       throw new Error(ERROR_REASONS.COLLECTION_NAME_IS_REQUIRED);
     }
     const res = await promisify(
-      this.client,
+      this.channelPool,
       'ListImportTasks',
       {
         ...data,
@@ -1171,7 +1171,7 @@ export class Data extends Collection {
   //   }
 
   //   const res = await promisify(
-  //     this.client,
+  //     this.channelPool,
   //     'ListIndexedSegment',
   //     data,
   //     data.timeout || this.timeout
@@ -1213,7 +1213,7 @@ export class Data extends Collection {
   //   }
 
   //   const res = await promisify(
-  //     this.client,
+  //     this.channelPool,
   //     'DescribeSegmentIndexData',
   //     data,
   //     data.timeout || this.timeout
diff --git a/milvus/grpc/Database.ts b/milvus/grpc/Database.ts
index 3322c33f..d3927c1d 100644
--- a/milvus/grpc/Database.ts
+++ b/milvus/grpc/Database.ts
@@ -37,7 +37,7 @@ export class Database extends BaseClient {
     });
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'CreateDatabase',
       data,
       data.timeout || this.timeout
@@ -74,7 +74,7 @@ export class Database extends BaseClient {
     });
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'ListDatabases',
       {},
       data?.timeout || this.timeout
@@ -110,7 +110,7 @@ export class Database extends BaseClient {
     });
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DropDatabase',
       data,
       data.timeout || this.timeout
diff --git a/milvus/grpc/GrpcClient.ts b/milvus/grpc/GrpcClient.ts
index eccf0545..287dc85a 100644
--- a/milvus/grpc/GrpcClient.ts
+++ b/milvus/grpc/GrpcClient.ts
@@ -1,6 +1,11 @@
-import { readFileSync } from 'fs';
-import { credentials, Metadata, ChannelCredentials } from '@grpc/grpc-js';
+import {
+  Metadata,
+  ServiceClientConstructor,
+  ChannelOptions,
+  Client,
+} from '@grpc/grpc-js';
 import dayjs from 'dayjs';
+import { createPool } from 'generic-pool';
 import {
   GetVersionResponse,
   CheckHealthResponse,
@@ -17,7 +22,9 @@ import {
   METADATA,
   logger,
   CONNECT_STATUS,
-  TLS_MODE,
+  ClientConfig,
+  DEFAULT_POOL_MAX,
+  DEFAULT_POOL_MIN,
 } from '../';
 import { User } from './User';
 
@@ -25,14 +32,39 @@ import { User } from './User';
  * A client for interacting with the Milvus server via gRPC.
  */
 export class GRPCClient extends User {
-  // create a grpc service client(connect)
-  connect(sdkVersion: string) {
-    // get Milvus GRPC service
+  /**
+   * Creates a new instance of MilvusClient.
+   * @param configOrAddress The Milvus server's address or client configuration object.
+   * @param ssl Whether to use SSL or not.
+   * @param username The username for authentication.
+   * @param password The password for authentication.
+   * @param channelOptions Additional channel options for gRPC.
+   */
+  constructor(
+    configOrAddress: ClientConfig | string,
+    ssl?: boolean,
+    username?: string,
+    password?: string,
+    channelOptions?: ChannelOptions
+  ) {
+    // setup the configuration
+    super(configOrAddress, ssl, username, password, channelOptions);
+
+    // Get the gRPC service for Milvus
     const MilvusService = getGRPCService({
       protoPath: this.protoFilePath.milvus,
       serviceName: this.protoInternalPath.serviceName, // the name of the Milvus service
     });
 
+    // setup auth if necessary
+    const auth = getAuthString(this.config);
+    if (auth.length > 0) {
+      this.metadata.set(METADATA.AUTH, auth);
+    }
+
+    // setup database
+    this.metadata.set(METADATA.DATABASE, this.config.database || DEFAULT_DB);
+
     // meta interceptor, add the injector
     const metaInterceptor = getMetaInterceptor(
       this.metadataListener.bind(this)
@@ -50,76 +82,61 @@ export class GRPCClient extends User {
           : this.config.retryDelay,
       clientId: this.clientId,
     });
+
     // interceptors
     const interceptors = [metaInterceptor, retryInterceptor];
 
     // add interceptors
     this.channelOptions.interceptors = interceptors;
 
-    // setup auth if necessary
-    const auth = getAuthString(this.config);
-    if (auth.length > 0) {
-      this.metadata.set(METADATA.AUTH, auth);
-    }
-
-    // setup database
-    this.metadata.set(METADATA.DATABASE, this.config.database || DEFAULT_DB);
-
-    // create credentials
-    let creds: ChannelCredentials;
-
-    // assign credentials according to the tls mode
-    switch (this.tlsMode) {
-      case TLS_MODE.ONE_WAY:
-        // create ssl with empty parameters
-        creds = credentials.createSsl();
-        break;
-      case TLS_MODE.TWO_WAY:
-        const { rootCertPath, privateKeyPath, certChainPath, verifyOptions } =
-          this.config.tls!;
-
-        // init
-        let rootCertBuff: Buffer | null = null;
-        let privateKeyBuff: Buffer | null = null;
-        let certChainBuff: Buffer | null = null;
-
-        // read root cert file
-        if (rootCertPath) {
-          rootCertBuff = readFileSync(rootCertPath);
-        }
-
-        // read private key file
-        if (privateKeyPath) {
-          privateKeyBuff = readFileSync(privateKeyPath);
-        }
+    // create grpc pool
+    this.channelPool = this.createChannelPool(MilvusService);
+  }
 
-        // read cert chain file
-        if (certChainPath) {
-          certChainBuff = readFileSync(certChainPath);
-        }
+  // create a grpc service client(connect)
+  connect(sdkVersion: string) {
+    // connect to get identifier
+    this.connectPromise = this._getServerInfo(sdkVersion);
+  }
 
-        // create credentials
-        creds = credentials.createSsl(
-          rootCertBuff,
-          privateKeyBuff,
-          certChainBuff,
-          verifyOptions
-        );
-        break;
-      default:
-        creds = credentials.createInsecure();
-        break;
-    }
+  // return client acquired from pool
+  get client() {
+    return this.channelPool.acquire();
+  }
 
-    // create grpc client
-    this.client = new MilvusService(
-      formatAddress(this.config.address), // format the address
-      creds,
-      this.channelOptions
+  /**
+   * Creates a pool of gRPC service clients.
+   *
+   * @param {ServiceClientConstructor} ServiceClientConstructor - The constructor for the gRPC service client.
+   *
+   * @returns {Pool} - A pool of gRPC service clients.
+   */
+  private createChannelPool(
+    ServiceClientConstructor: ServiceClientConstructor
+  ) {
+    return createPool(
+      {
+        create: async () => {
+          // Create a new gRPC service client
+          return new ServiceClientConstructor(
+            formatAddress(this.config.address), // format the address
+            this.creds,
+            this.channelOptions
+          );
+        },
+        destroy: async (client: Client) => {
+          // Close the gRPC service client
+          return new Promise<any>((resolve, reject) => {
+            client.close();
+            resolve(client.getChannel().getConnectivityState(true));
+          });
+        },
+      },
+      this.config.pool ?? {
+        min: DEFAULT_POOL_MIN,
+        max: DEFAULT_POOL_MAX,
+      }
     );
-
-    // connect to get identifier
-    this.connectPromise = this._getServerInfo(sdkVersion);
   }
 
   /**
@@ -177,43 +194,40 @@ export class GRPCClient extends User {
     // update connect status
     this.connectStatus = CONNECT_STATUS.CONNECTING;
 
-    return promisify(this.client, 'Connect', userInfo, this.timeout).then(f => {
-      // add new identifier interceptor
-      if (f && f.identifier) {
-        // update identifier
-        this.metadata.set(METADATA.CLIENT_ID, f.identifier);
+    return promisify(this.channelPool, 'Connect', userInfo, this.timeout).then(
+      f => {
+        // add new identifier interceptor
+        if (f && f.identifier) {
+          // update identifier
+          this.metadata.set(METADATA.CLIENT_ID, f.identifier);
 
-        // setup identifier
-        this.serverInfo = f.server_info;
+          // setup identifier
+          this.serverInfo = f.server_info;
+        }
+        // update connect status
+        this.connectStatus =
+          f && f.identifier
+            ? CONNECT_STATUS.CONNECTED
+            : CONNECT_STATUS.UNIMPLEMENTED;
       }
-      // update connect status
-      this.connectStatus =
-        f && f.identifier
-          ? CONNECT_STATUS.CONNECTED
-          : CONNECT_STATUS.UNIMPLEMENTED;
-    });
+    );
   }
 
   /**
-   * Closes the gRPC client connection and returns the connectivity state of the channel.
-   * This method should be called before terminating the application or when the client is no longer needed.
-   * This method returns a number that represents the connectivity state of the channel:
-   * - 0: CONNECTING
-   * - 1: READY
-   * - 2: IDLE
-   * - 3: TRANSIENT FAILURE
-   * - 4: FATAL FAILURE
-   * - 5: SHUTDOWN
+   * Closes the connection to the Milvus server.
+   * This method drains and clears the connection pool, and updates the connection status to SHUTDOWN.
+   * @returns {Promise<CONNECT_STATUS>} The updated connection status.
    */
-  closeConnection() {
-    // Close the gRPC client connection
-    if (this.client) {
-      this.client.close();
-    }
-    // grpc client closed -> 4, connected -> 0
-    if (this.client) {
-      return this.client.getChannel().getConnectivityState(true);
+  async closeConnection() {
+    // Close all connections in the pool
+    if (this.channelPool) {
+      await this.channelPool.drain();
+      await this.channelPool.clear();
+
+      // update status
+      this.connectStatus = CONNECT_STATUS.SHUTDOWN;
     }
+    return this.connectStatus;
   }
 
   /**
@@ -221,7 +235,7 @@ export class GRPCClient extends User {
    * This method returns a Promise that resolves with a `GetVersionResponse` object.
    */
   async getVersion(): Promise<GetVersionResponse> {
-    return await promisify(this.client, 'GetVersion', {}, this.timeout);
+    return await promisify(this.channelPool, 'GetVersion', {}, this.timeout);
   }
 
   /**
@@ -229,6 +243,6 @@ export class GRPCClient extends User {
    * This method returns a Promise that resolves with a `CheckHealthResponse` object.
    */
   async checkHealth(): Promise<CheckHealthResponse> {
-    return await promisify(this.client, 'CheckHealth', {}, this.timeout);
+    return await promisify(this.channelPool, 'CheckHealth', {}, this.timeout);
   }
 }
diff --git a/milvus/grpc/MilvusIndex.ts b/milvus/grpc/MilvusIndex.ts
index 607880f2..c31ac9b3 100644
--- a/milvus/grpc/MilvusIndex.ts
+++ b/milvus/grpc/MilvusIndex.ts
@@ -88,7 +88,7 @@ export class Index extends Data {
 
     // Call the 'CreateIndex' gRPC method and return the result
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'CreateIndex',
       createIndexParams,
       data.timeout || this.timeout
@@ -124,7 +124,7 @@ export class Index extends Data {
   async describeIndex(data: DescribeIndexReq): Promise<DescribeIndexResponse> {
     checkCollectionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DescribeIndex',
       data,
       data.timeout || this.timeout
@@ -160,7 +160,7 @@ export class Index extends Data {
   async getIndexState(data: GetIndexStateReq): Promise<GetIndexStateResponse> {
     checkCollectionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'GetIndexState',
       data,
       data.timeout || this.timeout
@@ -201,7 +201,7 @@ export class Index extends Data {
   ): Promise<GetIndexBuildProgressResponse> {
     checkCollectionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'GetIndexBuildProgress',
       data,
       data.timeout || this.timeout
@@ -239,7 +239,7 @@ export class Index extends Data {
   async dropIndex(data: DropIndexReq): Promise<ResStatus> {
     checkCollectionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DropIndex',
       data,
       data.timeout || this.timeout
diff --git a/milvus/grpc/Partition.ts b/milvus/grpc/Partition.ts
index 20e78d5d..88d8139f 100644
--- a/milvus/grpc/Partition.ts
+++ b/milvus/grpc/Partition.ts
@@ -48,7 +48,7 @@ export class Partition extends Index {
   async createPartition(data: CreatePartitionReq): Promise<ResStatus> {
     checkCollectionAndPartitionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'CreatePartition',
       data,
       data.timeout || this.timeout
@@ -85,7 +85,7 @@ export class Partition extends Index {
   async hasPartition(data: HasPartitionReq): Promise<BoolResponse> {
     checkCollectionAndPartitionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'HasPartition',
       data,
       data.timeout || this.timeout
@@ -124,7 +124,7 @@ export class Partition extends Index {
   ): Promise<ShowPartitionsResponse> {
     checkCollectionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'ShowPartitions',
       data,
       data.timeout || this.timeout
@@ -165,7 +165,7 @@ export class Partition extends Index {
   ): Promise<StatisticsResponse> {
     checkCollectionAndPartitionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'GetPartitionStatistics',
       data,
       data.timeout || this.timeout
@@ -207,7 +207,7 @@ export class Partition extends Index {
       throw new Error(ERROR_REASONS.PARTITION_NAMES_IS_REQUIRED);
     }
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'LoadPartitions',
       data,
       data.timeout || this.timeout
@@ -247,7 +247,7 @@ export class Partition extends Index {
       throw new Error(ERROR_REASONS.PARTITION_NAMES_IS_REQUIRED);
     }
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'ReleasePartitions',
       data,
       data.timeout || this.timeout
@@ -290,7 +290,7 @@ export class Partition extends Index {
   async dropPartition(data: DropPartitionReq): Promise<ResStatus> {
     checkCollectionAndPartitionName(data);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DropPartition',
       data,
       data.timeout || this.timeout
diff --git a/milvus/grpc/Resource.ts b/milvus/grpc/Resource.ts
index 997f3b7a..36ce0733 100644
--- a/milvus/grpc/Resource.ts
+++ b/milvus/grpc/Resource.ts
@@ -39,7 +39,7 @@ export class Resource extends Partition {
    */
   async createResourceGroup(data: CreateResourceGroupReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'CreateResourceGroup',
       data,
       data.timeout || this.timeout
@@ -68,7 +68,7 @@ export class Resource extends Partition {
     data?: GrpcTimeOut
   ): Promise<ListResourceGroupsResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'ListResourceGroups',
       {},
       data?.timeout || this.timeout
@@ -108,7 +108,7 @@ export class Resource extends Partition {
     data: DescribeResourceGroupsReq
   ): Promise<DescribeResourceGroupResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DescribeResourceGroup',
       data,
       data.timeout || this.timeout
@@ -140,7 +140,7 @@ export class Resource extends Partition {
    */
   async dropResourceGroup(data: DropResourceGroupsReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DropResourceGroup',
       data,
       data.timeout || this.timeout
@@ -180,7 +180,7 @@ export class Resource extends Partition {
   /* istanbul ignore next */
   async transferReplica(data: TransferReplicaReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'TransferReplica',
       data,
       data.timeout || this.timeout
@@ -218,7 +218,7 @@ export class Resource extends Partition {
   /* istanbul ignore next */
   async transferNode(data: TransferNodeReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'TransferNode',
       data,
       data.timeout || this.timeout
diff --git a/milvus/grpc/User.ts b/milvus/grpc/User.ts
index 062056ae..e836fa56 100644
--- a/milvus/grpc/User.ts
+++ b/milvus/grpc/User.ts
@@ -61,7 +61,7 @@ export class User extends Resource {
     }
     const encryptedPassword = stringToBase64(data.password);
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'CreateCredential',
       {
         username: data.username,
@@ -110,7 +110,7 @@ export class User extends Resource {
     const encryptedNewPwd = stringToBase64(data.newPassword);
 
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'UpdateCredential',
       {
         username: data.username,
@@ -150,7 +150,7 @@ export class User extends Resource {
       throw new Error(ERROR_REASONS.USERNAME_IS_REQUIRED);
     }
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DeleteCredential',
       {
         username: data.username,
@@ -182,7 +182,7 @@ export class User extends Resource {
    */
   async listUsers(data?: ListUsersReq): Promise<ListCredUsersResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'ListCredUsers',
       {},
       data?.timeout || this.timeout
@@ -213,7 +213,7 @@ export class User extends Resource {
    */
   async createRole(data: CreateRoleReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'CreateRole',
       {
         entity: { name: data.roleName },
@@ -246,7 +246,7 @@ export class User extends Resource {
    */
   async dropRole(data: DropRoleReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'DropRole',
       {
         role_name: data.roleName,
@@ -280,7 +280,7 @@ export class User extends Resource {
    */
   async addUserToRole(data: AddUserToRoleReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'OperateUserRole',
       {
         username: data.username,
@@ -316,7 +316,7 @@ export class User extends Resource {
    */
   async removeUserFromRole(data: RemoveUserFromRoleReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'OperateUserRole',
       {
         username: data.username,
@@ -352,7 +352,7 @@ export class User extends Resource {
    */
   async selectRole(data: SelectRoleReq): Promise<SelectRoleResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'SelectRole',
       {
         role: { name: data.roleName },
@@ -386,7 +386,7 @@ export class User extends Resource {
    */
   async listRoles(data?: listRoleReq): Promise<SelectRoleResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'SelectRole',
       {
         include_user_info: data?.includeUserInfo || true,
@@ -420,7 +420,7 @@ export class User extends Resource {
    */
   async selectUser(data: SelectUserReq): Promise<SelectUserResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'SelectUser',
       {
         user: { name: data.username },
@@ -463,7 +463,7 @@ export class User extends Resource {
    */
   async grantRolePrivilege(data: OperateRolePrivilegeReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'OperatePrivilege',
       {
         entity: {
@@ -513,7 +513,7 @@ export class User extends Resource {
    */
   async revokeRolePrivilege(data: OperateRolePrivilegeReq): Promise<ResStatus> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'OperatePrivilege',
       {
         entity: {
@@ -621,7 +621,7 @@ export class User extends Resource {
    */
   async selectGrant(data: SelectGrantReq): Promise<SelectGrantResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'SelectGrant',
       {
         entity: {
@@ -663,7 +663,7 @@ export class User extends Resource {
    */
   async listGrants(data: ListGrantsReq): Promise<SelectGrantResponse> {
     const promise = await promisify(
-      this.client,
+      this.channelPool,
       'SelectGrant',
       {
         entity: {
diff --git a/milvus/types/Client.ts b/milvus/types/Client.ts
index 7a5a45a2..033e08a0 100644
--- a/milvus/types/Client.ts
+++ b/milvus/types/Client.ts
@@ -1,4 +1,5 @@
 import { ChannelOptions } from '@grpc/grpc-js';
+import { Options } from 'generic-pool';
 
 /**
  * Configuration options for the Milvus client.
@@ -46,6 +47,12 @@ export interface ClientConfig {
     // server name
     serverName?: string;
   };
+
+  // generic-pool options: refer to https://github.com/coopernurse/node-pool
+  pool?: Options;
+
+  // internal property for debug & test
+  __SKIP_CONNECT__?: boolean;
 }
 
 export interface ServerInfo {
diff --git a/milvus/utils/Function.ts b/milvus/utils/Function.ts
index e9bf95ea..cc797b63 100644
--- a/milvus/utils/Function.ts
+++ b/milvus/utils/Function.ts
@@ -1,4 +1,5 @@
 import { KeyValuePair, DataType, ERROR_REASONS } from '../';
+import { Pool } from 'generic-pool';
 
 /**
  * Promisify a function call with optional timeout
@@ -8,8 +9,8 @@ import { KeyValuePair, DataType, ERROR_REASONS } from '../';
  * @param timeout - Optional timeout in milliseconds
  * @returns A Promise that resolves with the result of the target function call
  */
-export function promisify(
-  obj: any,
+export async function promisify(
+  pool: Pool<any>,
   target: string,
   params: any,
   timeout: number
@@ -17,11 +18,14 @@ export function promisify(
   // Calculate the deadline for the function call
   const t = timeout === 0 ? 1000 * 60 * 60 * 24 : timeout;
 
+  // get client
+  const client = await pool.acquire();
+
   // Create a new Promise that wraps the target function call
-  const res = new Promise((resolve, reject) => {
+  return new Promise((resolve, reject) => {
     try {
       // Call the target function with the provided parameters and deadline
-      obj[target](
+      client[target](
         params,
         { deadline: new Date(Date.now() + t) },
         (err: any, result: any) => {
@@ -34,16 +38,13 @@ export function promisify(
         }
       );
     } catch (e: any) {
-      // If there was an exception, throw a new Error
-      throw new Error(e);
+      reject(e);
+    } finally {
+      if (client) {
+        pool.release(client);
+      }
     }
-  }).catch(err => {
-    // Return a rejected Promise with the error
-    return Promise.reject(err);
   });
-
-  // Return the Promise
-  return res;
 }
 
 export const findKeyValue = (obj: KeyValuePair[], key: string) =>
diff --git a/package.json b/package.json
index b295574f..bb650b92 100644
--- a/package.json
+++ b/package.json
@@ -23,6 +23,7 @@
     "@grpc/grpc-js": "1.8.17",
     "@grpc/proto-loader": "0.7.7",
     "dayjs": "^1.11.7",
+    "generic-pool": "^3.9.0",
     "lru-cache": "^9.1.2",
     "protobufjs": "7.2.4",
     "winston": "^3.9.0"
diff --git a/test/grpc/Collection.spec.ts b/test/grpc/Collection.spec.ts
index 97acd30c..538ff54d 100644
--- a/test/grpc/Collection.spec.ts
+++ b/test/grpc/Collection.spec.ts
@@ -513,7 +513,9 @@ describe(`Collection API`, () => {
       collection_name: LOAD_COLLECTION_NAME,
     });
 
-    expect(Number(formatKeyValueData(describe.properties, [key])[key])).toEqual(value);
+    expect(Number(formatKeyValueData(describe.properties, [key])[key])).toEqual(
+      value
+    );
   });
 
   it(`Create alias success`, async () => {
diff --git a/test/grpc/MilvusClient.spec.ts b/test/grpc/MilvusClient.spec.ts
index 030f44b5..c7ae8684 100644
--- a/test/grpc/MilvusClient.spec.ts
+++ b/test/grpc/MilvusClient.spec.ts
@@ -1,4 +1,10 @@
-import { MilvusClient, ERROR_REASONS, CONNECT_STATUS } from '../../milvus';
+import path from 'path';
+import {
+  MilvusClient,
+  ERROR_REASONS,
+  CONNECT_STATUS,
+  TLS_MODE,
+} from '../../milvus';
 import sdkInfo from '../../sdk.json';
 import { IP } from '../tools';
 
@@ -6,60 +12,85 @@ const milvusClient = new MilvusClient({
   address: IP,
 });
 
+// path
+const milvusProtoPath = path.resolve(
+  __dirname,
+  '../../proto/proto/milvus.proto'
+);
+const schemaProtoPath = path.resolve(
+  __dirname,
+  '../../proto/proto/schema.proto'
+);
+
 describe(`Milvus client`, () => {
   afterEach(() => {
     jest.clearAllMocks();
   });
 
-  // it(`should create a grpc client with cert file successfully`, async () => {
-  //   const milvusClient = new MilvusClient({
-  //     address: IP,
-  //     tls: {
-  //       rootCertPath: `test/cert/ca.pem`,
-  //       privateKeyPath: `test/cert/client.key`,
-  //       certChainPath: `test/cert/client.pem`,
-  //       serverName: IP,
-  //     },
-  //     id: '1',
-  //   });
-
-  //   expect(milvusClient.client).toBeDefined();
-  //   expect(milvusClient.tlsMode).toEqual(2);
-  //   expect(milvusClient.clientId).toEqual('1');
-  // });
-
-  it(`should create a grpc client without SSL credentials when ssl is false`, () => {
-    const milvusClient = new MilvusClient({
+  it(`should create a grpc client with cert file successfully`, async () => {
+    const m1 = new MilvusClient({
+      address: IP,
+      tls: {
+        rootCertPath: `test/cert/ca.pem`,
+        privateKeyPath: `test/cert/client.key`,
+        certChainPath: `test/cert/client.pem`,
+        serverName: IP,
+      },
+      id: '1',
+      __SKIP_CONNECT__: true,
+    });
+
+    expect(await m1.client).toBeDefined();
+    expect(m1.tlsMode).toEqual(TLS_MODE.TWO_WAY);
+    expect(m1.clientId).toEqual('1');
+  });
+
+  it(`should create a grpc client without SSL credentials when ssl is false`, async () => {
+    const m2 = new MilvusClient({
       address: IP,
-      ssl: false,
+      ssl: true,
       username: 'username',
       password: 'password',
       id: '1',
+      __SKIP_CONNECT__: true,
     });
 
-    expect(milvusClient.clientId).toEqual('1');
-    expect(milvusClient.client).toBeDefined();
+    expect(m2.clientId).toEqual('1');
+    expect(await m2.client).toBeDefined();
+    expect(m2.tlsMode).toEqual(TLS_MODE.ONE_WAY);
   });
 
   it(`should create a grpc client without authentication when username and password are not provided`, () => {
-    const milvusClient = new MilvusClient(IP, false);
-
-    expect(milvusClient.client).toBeDefined();
+    const m3 = new MilvusClient(IP, false);
+    expect(m3.client).toBeDefined();
   });
 
   it(`should have connect promise and connectStatus`, async () => {
-    const milvusClient = new MilvusClient(IP, false);
-    expect(milvusClient.connectPromise).toBeDefined();
+    const m4 = new MilvusClient(IP, false);
+    expect(m4.connectPromise).toBeDefined();
 
-    await milvusClient.connectPromise;
-    expect(milvusClient.connectStatus).not.toEqual(
-      CONNECT_STATUS.NOT_CONNECTED
-    );
+    await m4.connectPromise;
+    expect(m4.connectStatus).not.toEqual(CONNECT_STATUS.NOT_CONNECTED);
   });
 
-  it(`should create a grpc client with authentication when username and password are provided`, () => {
-    const milvusClient = new MilvusClient(IP, false, `username`, `password`);
-    expect(milvusClient.client).toBeDefined();
+  it(`should create a grpc client with authentication when username and password are provided`, async () => {
+    const m5 = new MilvusClient(IP, false, `username`, `password`);
+    expect(await m5.client).toBeDefined();
+  });
+
+  it(`should setup protofile path successfully`, async () => {
+    const m6 = new MilvusClient({
+      address: IP,
+      protoFilePath: {
+        milvus: milvusProtoPath,
+        schema: schemaProtoPath,
+      },
+      __SKIP_CONNECT__: true,
+    });
+
+    expect(await m6.client).toBeDefined();
+    expect(m6.protoFilePath.milvus).toEqual(milvusProtoPath);
+    expect(m6.protoFilePath.schema).toEqual(schemaProtoPath);
   });
 
   it(`Should throw MILVUS_ADDRESS_IS_REQUIRED`, async () => {
@@ -88,7 +119,10 @@ describe(`Milvus client`, () => {
   });
 
   it(`Expect close connection success`, async () => {
-    const res = milvusClient.closeConnection();
-    expect(res).toEqual(4);
+    expect(milvusClient.channelPool.size).toBeGreaterThan(0);
+
+    const res = await milvusClient.closeConnection();
+    expect(milvusClient.channelPool.size).toBe(0);
+    expect(res).toBe(CONNECT_STATUS.SHUTDOWN);
   });
 });
diff --git a/test/utils/Function.spec.ts b/test/utils/Function.spec.ts
index 3fa45c32..7cb61466 100644
--- a/test/utils/Function.spec.ts
+++ b/test/utils/Function.spec.ts
@@ -1,56 +1,49 @@
-import { promisify } from '../../milvus';
+import { promisify } from '../../milvus/utils';
 
-describe(`utils/function`, () => {
-  it('should resolve with the result of the target function call', async () => {
-    const obj = {
-      target: (params: any, options: any, callback: any) => {
-        callback(null, 'result');
-      },
+describe('promisify', () => {
+  let pool: any;
+  let client: any;
+
+  beforeEach(() => {
+    client = {
+      testFunction: jest.fn((params, options, callback) =>
+        callback(null, 'success')
+      ),
+    };
+    pool = {
+      acquire: jest.fn().mockResolvedValue(client),
+      release: jest.fn(),
     };
-    const target = 'target';
-    const params = {};
-    const timeout = 1000;
-    const result = await promisify(obj, target, params, timeout);
-    expect(result).toEqual('result');
   });
 
-  it('should reject with the error if there was an error', async () => {
-    const obj = {
-      target: (params: any, options: any, callback: any) => {
-        callback(new Error('error'));
-      },
-    };
-    const target = 'target';
-    const params = {};
-    const timeout = 1000;
-    await expect(promisify(obj, target, params, timeout)).rejects.toThrow(
+  it('should resolve with the result of the function call', async () => {
+    const result = await promisify(pool, 'testFunction', {}, 1000);
+    expect(result).toBe('success');
+    expect(client.testFunction).toHaveBeenCalled();
+    expect(pool.acquire).toHaveBeenCalled();
+    expect(pool.release).toHaveBeenCalled();
+  });
+
+  it('should reject if the function call results in an error', async () => {
+    client.testFunction = jest.fn((params, options, callback) =>
+      callback('error')
+    );
+    await expect(promisify(pool, 'testFunction', {}, 1000)).rejects.toBe(
       'error'
     );
+    expect(client.testFunction).toHaveBeenCalled();
+    expect(pool.acquire).toHaveBeenCalled();
+    expect(pool.release).toHaveBeenCalled();
   });
 
-  it('should reject with the error if there was an exception', async () => {
-    const obj = {
-      target: () => {
-        throw new Error('exception');
-      },
-    };
-    const target = 'target';
-    const params = {};
-    const timeout = 1000;
-    await expect(promisify(obj, target, params, timeout)).rejects.toThrow(
+  it('should reject if the function call throws an exception', async () => {
+    client.testFunction = jest.fn(() => {
+      throw new Error('exception');
+    });
+    await expect(promisify(pool, 'testFunction', {}, 1000)).rejects.toThrow(
       'exception'
     );
-  });
-
-  it('should use the default timeout if no timeout is provided', async () => {
-    const obj = {
-      target: (params: any, options: any, callback: any) => {
-        callback(null, 'result');
-      },
-    };
-    const target = 'target';
-    const params = {};
-    const result = await promisify(obj, target, params, 0);
-    expect(result).toEqual('result');
+    expect(pool.acquire).toHaveBeenCalled();
+    expect(pool.release).toHaveBeenCalled();
   });
 });
diff --git a/yarn.lock b/yarn.lock
index c8d1b0d7..69db35a1 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1472,6 +1472,11 @@ function-bind@^1.1.1:
   resolved "https://registry.yarnpkg.com/function-bind/-/function-bind-1.1.1.tgz#a56899d3ea3c9bab874bb9773b7c5ede92f4895d"
   integrity sha512-yIovAzMX49sF8Yl58fSCWJ5svSLuaibPxXQJFLmBObTuCr0Mf1KiPopGM9NiFjiYBCbfaa2Fh6breQ6ANVTI0A==
 
+generic-pool@^3.9.0:
+  version "3.9.0"
+  resolved "https://registry.yarnpkg.com/generic-pool/-/generic-pool-3.9.0.tgz#36f4a678e963f4fdb8707eab050823abc4e8f5e4"
+  integrity sha512-hymDOu5B53XvN4QT9dBmZxPX4CWhBPPLguTZ9MMFeFa/Kg0xWVfylOVNlJji/E7yTZWFd/q9GO5TxDLq156D7g==
+
 gensync@^1.0.0-beta.2:
   version "1.0.0-beta.2"
   resolved "https://registry.yarnpkg.com/gensync/-/gensync-1.0.0-beta.2.tgz#32a6ee76c3d7f52d46b2b1ae5d93fea8580a25e0"