fix: reduce Connection keep-alive timeout to 1 second fewer than the Solana RPC's keep-alive timeout (#29130)

* Delete `AgentManager`

* Replace custom `http.Agent` implementation with `agentkeepalive` package

* Set the default free socket timeout to 1s less than the Solana RPC's default timeout

* Add link to particular issue comment

* Create the correct flavor of default agent for http/https

web3.js/package.json

@@ -62,6 +62,7 @@
     "@noble/hashes": "^1.1.2",
     "@noble/secp256k1": "^1.6.3",
     "@solana/buffer-layout": "^4.0.0",
+    "agentkeepalive": "^4.2.1",
     "bigint-buffer": "^1.1.5",
     "bn.js": "^5.0.0",
     "borsh": "^0.7.0",

web3.js/src/agent-manager.ts

@@ -1,44 +0,0 @@
-import http from 'http';
-import https from 'https';
-
-export const DESTROY_TIMEOUT_MS = 5000;
-
-export class AgentManager {
-  _agent: http.Agent | https.Agent;
-  _activeRequests = 0;
-  _destroyTimeout: ReturnType<typeof setTimeout> | null = null;
-  _useHttps: boolean;
-
-  static _newAgent(useHttps: boolean): http.Agent | https.Agent {
-    const options = {keepAlive: true, maxSockets: 25};
-    if (useHttps) {
-      return new https.Agent(options);
-    } else {
-      return new http.Agent(options);
-    }
-  }
-
-  constructor(useHttps?: boolean) {
-    this._useHttps = useHttps === true;
-    this._agent = AgentManager._newAgent(this._useHttps);
-  }
-
-  requestStart(): http.Agent | https.Agent {
-    this._activeRequests++;
-    if (this._destroyTimeout !== null) {
-      clearTimeout(this._destroyTimeout);
-      this._destroyTimeout = null;
-    }
-    return this._agent;
-  }
-
-  requestEnd() {
-    this._activeRequests--;
-    if (this._activeRequests === 0 && this._destroyTimeout === null) {
-      this._destroyTimeout = setTimeout(() => {
-        this._agent.destroy();
-        this._agent = AgentManager._newAgent(this._useHttps);
-      }, DESTROY_TIMEOUT_MS);
-    }
-  }
-}

web3.js/src/connection.ts

@@ -1,9 +1,12 @@
+import HttpKeepAliveAgent, {
+  HttpsAgent as HttpsKeepAliveAgent,
+} from 'agentkeepalive';
 import bs58 from 'bs58';
 import {Buffer} from 'buffer';
 // @ts-ignore
 import fastStableStringify from 'fast-stable-stringify';
-import type {Agent as HttpAgent} from 'http';
+import type {Agent as NodeHttpAgent} from 'http';
-import {Agent as HttpsAgent} from 'https';
+import {Agent as NodeHttpsAgent} from 'https';
 import {
   type as pick,
   number,
@@ -27,7 +30,6 @@ import {Client as RpcWebSocketClient} from 'rpc-websockets';
 import RpcClient from 'jayson/lib/client/browser';
 import {JSONRPCError} from 'jayson';
 
-import {AgentManager} from './agent-manager';
 import {EpochSchedule} from './epoch-schedule';
 import {SendTransactionError, SolanaJSONRPCError} from './errors';
 import fetchImpl, {Response} from './fetch-impl';
@@ -1452,12 +1454,10 @@ function createRpcClient(
   customFetch?: FetchFn,
   fetchMiddleware?: FetchMiddleware,
   disableRetryOnRateLimit?: boolean,
-  httpAgent?: HttpAgent | HttpsAgent | false,
+  httpAgent?: NodeHttpAgent | NodeHttpsAgent | false,
 ): RpcClient {
   const fetch = customFetch ? customFetch : fetchImpl;
-  let agentManager:
+  let agent: NodeHttpAgent | NodeHttpsAgent | undefined;
-    | {requestEnd(): void; requestStart(): HttpAgent | HttpsAgent}
-    | undefined;
   if (process.env.BROWSER) {
     if (httpAgent != null) {
       console.warn(
@@ -1468,21 +1468,30 @@ function createRpcClient(
   } else {
     if (httpAgent == null) {
       if (process.env.NODE_ENV !== 'test') {
-        agentManager = new AgentManager(
+        const agentOptions = {
-          url.startsWith('https:') /* useHttps */,
+          // One second fewer than the Solana RPC's keepalive timeout.
-        );
+          // Read more: https://github.com/solana-labs/solana/issues/27859#issuecomment-1340097889
+          freeSocketTimeout: 19000,
+          keepAlive: true,
+          maxSockets: 25,
+        };
+        if (url.startsWith('https:')) {
+          agent = new HttpsKeepAliveAgent(agentOptions);
+        } else {
+          agent = new HttpKeepAliveAgent(agentOptions);
+        }
       }
     } else {
       if (httpAgent !== false) {
         const isHttps = url.startsWith('https:');
-        if (isHttps && !(httpAgent instanceof HttpsAgent)) {
+        if (isHttps && !(httpAgent instanceof NodeHttpsAgent)) {
           throw new Error(
             'The endpoint `' +
               url +
               '` can only be paired with an `https.Agent`. You have, instead, supplied an ' +
               '`http.Agent` through `httpAgent`.',
           );
-        } else if (!isHttps && httpAgent instanceof HttpsAgent) {
+        } else if (!isHttps && httpAgent instanceof NodeHttpsAgent) {
           throw new Error(
             'The endpoint `' +
               url +
@@ -1490,7 +1499,7 @@ function createRpcClient(
               '`https.Agent` through `httpAgent`.',
           );
         }
-        agentManager = {requestEnd() {}, requestStart: () => httpAgent};
+        agent = httpAgent;
       }
     }
   }
@@ -1515,7 +1524,6 @@ function createRpcClient(
   }
 
   const clientBrowser = new RpcClient(async (request, callback) => {
-    const agent = agentManager ? agentManager.requestStart() : undefined;
     const options = {
       method: 'POST',
       body: request,
@@ -1565,8 +1573,6 @@ function createRpcClient(
       }
     } catch (err) {
       if (err instanceof Error) callback(err);
-    } finally {
-      agentManager && agentManager.requestEnd();
     }
   }, {});
 
@@ -2898,7 +2904,7 @@ export type ConnectionConfig = {
    * persistence). Set this to `false` to create a connection that uses no agent. This applies to
    * Node environments only.
    */
-  httpAgent?: HttpAgent | HttpsAgent | false;
+  httpAgent?: NodeHttpAgent | NodeHttpsAgent | false;
   /** Optional commitment level */
   commitment?: Commitment;
   /** Optional endpoint URL to the fullnode JSON RPC PubSub WebSocket Endpoint */

web3.js/test/agent-manager.test.ts

@@ -1,40 +0,0 @@
-import {expect} from 'chai';
-
-import {AgentManager, DESTROY_TIMEOUT_MS} from '../src/agent-manager';
-import {sleep} from '../src/utils/sleep';
-
-describe('AgentManager', () => {
-  it('works', async () => {
-    const manager = new AgentManager();
-    const agent = manager._agent;
-    expect(manager._activeRequests).to.eq(0);
-    expect(manager._destroyTimeout).to.be.null;
-
-    manager.requestStart();
-
-    expect(manager._activeRequests).to.eq(1);
-    expect(manager._destroyTimeout).to.be.null;
-
-    manager.requestEnd();
-
-    expect(manager._activeRequests).to.eq(0);
-    expect(manager._destroyTimeout).not.to.be.null;
-
-    manager.requestStart();
-    manager.requestStart();
-
-    expect(manager._activeRequests).to.eq(2);
-    expect(manager._destroyTimeout).to.be.null;
-
-    manager.requestEnd();
-    manager.requestEnd();
-
-    expect(manager._activeRequests).to.eq(0);
-    expect(manager._destroyTimeout).not.to.be.null;
-    expect(manager._agent).to.eq(agent);
-
-    await sleep(DESTROY_TIMEOUT_MS);
-
-    expect(manager._agent).not.to.eq(agent);
-  }).timeout(2 * DESTROY_TIMEOUT_MS);
-});

web3.js/yarn.lock

@@ -1834,7 +1834,7 @@ agent-base@6, agent-base@^6.0.0, agent-base@^6.0.2:
   dependencies:
     debug "4"
 
-agentkeepalive@^4.1.3, agentkeepalive@^4.2.1:
+agentkeepalive@^4.1.3:
   version "4.2.1"
   resolved "https://registry.npmjs.org/agentkeepalive/-/agentkeepalive-4.2.1.tgz"
   dependencies:
@@ -1842,6 +1842,15 @@ agentkeepalive@^4.1.3, agentkeepalive@^4.2.1:
     depd "^1.1.2"
     humanize-ms "^1.2.1"
 
+agentkeepalive@^4.2.1:
+  version "4.2.1"
+  resolved "https://registry.yarnpkg.com/agentkeepalive/-/agentkeepalive-4.2.1.tgz#a7975cbb9f83b367f06c90cc51ff28fe7d499717"
+  integrity sha512-Zn4cw2NEqd+9fiSVWMscnjyQ1a8Yfoc5oBajLeo5w+YBHgDUcEBY2hS4YpTz6iN5f/2zQiktcuM6tS8x1p9dpA==
+  dependencies:
+    debug "^4.1.0"
+    depd "^1.1.2"
+    humanize-ms "^1.2.1"
+
 aggregate-error@^3.0.0:
   version "3.1.0"
   resolved "https://registry.npmjs.org/aggregate-error/-/aggregate-error-3.1.0.tgz"