net: set default highwatermark at socket creation time

doc/api/http.md

@@ -3448,7 +3448,8 @@ changes:
   * `highWaterMark` {number} Optionally overrides all `socket`s'
     `readableHighWaterMark` and `writableHighWaterMark`. This affects
     `highWaterMark` property of both `IncomingMessage` and `ServerResponse`.
-    **Default:** See [`stream.getDefaultHighWaterMark()`][].
+    **Default:** `undefined`. Sockets will use the default watermark value
+    at the time the request arrives. See [`stream.getDefaultHighWaterMark()`][].
   * `insecureHTTPParser` {boolean} If set to `true`, it will use a HTTP parser
     with leniency flags enabled. Using the insecure parser should be avoided.
     See [`--insecure-http-parser`][] for more information.

lib/net.js

@@ -156,7 +156,6 @@ const {
   startPerf,
   stopPerf,
 } = require('internal/perf/observe');
-const { getDefaultHighWaterMark } = require('internal/streams/state');
 
 function getFlags(ipv6Only) {
   return ipv6Only === true ? TCPConstants.UV_TCP_IPV6ONLY : 0;
@@ -1735,11 +1734,8 @@ function Server(options, connectionListener) {
   if (typeof options.highWaterMark !== 'undefined') {
     validateNumber(
       options.highWaterMark, 'options.highWaterMark',
+      0,
     );
-
-    if (options.highWaterMark < 0) {
-      options.highWaterMark = getDefaultHighWaterMark();
-    }
   }
 
   this._connections = 0;
@@ -1755,7 +1751,7 @@ function Server(options, connectionListener) {
   this.noDelay = Boolean(options.noDelay);
   this.keepAlive = Boolean(options.keepAlive);
   this.keepAliveInitialDelay = ~~(options.keepAliveInitialDelay / 1000);
-  this.highWaterMark = options.highWaterMark ?? getDefaultHighWaterMark();
+  this.highWaterMark = options.highWaterMark;
 }
 ObjectSetPrototypeOf(Server.prototype, EventEmitter.prototype);
 ObjectSetPrototypeOf(Server, EventEmitter);

test/parallel/test-http-server-options-highwatermark.js

@@ -5,7 +5,7 @@ const assert = require('assert');
 const http = require('http');
 const { kHighWaterMark } = require('_http_outgoing');
 
-const { getDefaultHighWaterMark } = require('internal/streams/state');
+const { setDefaultHighWaterMark } = require('internal/streams/state');
 
 function listen(server) {
   server.listen(0, common.mustCall(() => {
@@ -20,28 +20,44 @@ function listen(server) {
   }));
 }
 
+// Test `options.highWaterMark` fails if less than zero.
 {
+  assert.throws(() => {
+    http.createServer({
+      highWaterMark: -1,
+    });
+  }, { code: 'ERR_OUT_OF_RANGE' });
+}
+
+// Test socket watermark is set with the value in `options.highWaterMark`.
+{
+  const waterMarkValue = 17000;
+  const serverWaterMarkValue = 14000;
   const server = http.createServer({
-    highWaterMark: getDefaultHighWaterMark() * 2,
+    highWaterMark: serverWaterMarkValue,
   }, common.mustCall((req, res) => {
-    assert.strictEqual(req._readableState.highWaterMark, getDefaultHighWaterMark() * 2);
-    assert.strictEqual(res[kHighWaterMark], getDefaultHighWaterMark() * 2);
+    assert.strictEqual(req._readableState.highWaterMark, serverWaterMarkValue);
+    assert.strictEqual(res[kHighWaterMark], serverWaterMarkValue);
     res.statusCode = 200;
     res.end();
   }));
 
+  setDefaultHighWaterMark(false, waterMarkValue);
   listen(server);
 }
 
+// Test socket watermark is the default if `highWaterMark` in `options` is unset.
 {
+  const waterMarkValue = 13000;
   const server = http.createServer(
     common.mustCall((req, res) => {
-      assert.strictEqual(req._readableState.highWaterMark, getDefaultHighWaterMark());
-      assert.strictEqual(res[kHighWaterMark], getDefaultHighWaterMark());
+      assert.strictEqual(req._readableState.highWaterMark, waterMarkValue);
+      assert.strictEqual(res[kHighWaterMark], waterMarkValue);
       res.statusCode = 200;
       res.end();
     })
   );
 
+  setDefaultHighWaterMark(false, waterMarkValue);
   listen(server);
 }