Skip to content

http2: tune control flow defaults #61036

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
ronag wants to merge 2 commits into
base: main
Choose a base branch
from
+16 −5
Open

http2: tune control flow defaults #61036

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
f6fa8fa
http2: tune control flow defaults
ronag Dec 12, 2025
bb77aed
fixup
ronag Dec 14, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 2 additions & 2 deletions doc/api/http2.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3541,10 +3541,10 @@ properties.
permitted on the `Http2Session` instances. **Default:** `true`.
* `initialWindowSize` {number} Specifies the _sender's_ initial window size in
bytes for stream-level flow control. The minimum allowed value is 0. The
maximum allowed value is 2<sup>32</sup>-1. **Default:** `65535`.
maximum allowed value is 2<sup>32</sup>-1. **Default:** `262144`.
* `maxFrameSize` {number} Specifies the size in bytes of the largest frame
payload. The minimum allowed value is 16,384. The maximum allowed value is
2<sup>24</sup>-1. **Default:** `16384`.
2<sup>24</sup>-1. **Default:** `32768`.
* `maxConcurrentStreams` {number} Specifies the maximum number of concurrent
streams permitted on an `Http2Session`. There is no default value which
implies, at least theoretically, 2<sup>32</sup>-1 streams may be open
Expand Down
6 changes: 5 additions & 1 deletion lib/internal/http2/core.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3288,12 +3288,16 @@ function connectionListener(socket) {

socket[kServer] = this;

// NGHTTP2_INITIAL_CONNECTION_WINDOW_SIZE default is 64KB, but we want to allow more data to be
// buffered without applying backpressure.
session.setLocalWindowSize(512 * 1024);

this.emit('session', session);
}

function initializeOptions(options) {
assertIsObject(options, 'options');
options = { ...options };
options = { ...getDefaultSettings(), ...options };
Copy link
Member Author

@ronag ronag Dec 12, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We should actually apply the default settings and not just assume that they are the same as nghttp2 will do.

assertIsObject(options.settings, 'options.settings');
options.settings = { ...options.settings };

Expand Down
7 changes: 7 additions & 0 deletions lib/internal/http2/util.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -364,6 +364,13 @@ function getDefaultSettings() {
settingsBuffer[IDX_SETTINGS_ENABLE_CONNECT_PROTOCOL] === 1;
}

// NGHTTP2_INITIAL_WINDOW_SIZE default is 64KB, but we want to allow more data to be
// buffered without applying backpressure.
holder.initialWindowSize = MathMax(holder.initialWindowSize, 256 * 1024);

// Default is 16KB.
holder.maxFrameSize = MathMax(32 * 1024, holder.maxFrameSize);

if (settingsBuffer[IDX_SETTINGS_FLAGS + 1]) holder.customSettings = addCustomSettingsToObj();

return holder;
Expand Down
4 changes: 2 additions & 2 deletions test/parallel/test-http2-binding.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,8 +17,8 @@ const settings = http2.getDefaultSettings();
assert.strictEqual(settings.headerTableSize, 4096);
assert.strictEqual(settings.enablePush, true);
assert.strictEqual(settings.maxConcurrentStreams, 4294967295);
assert.strictEqual(settings.initialWindowSize, 65535);
assert.strictEqual(settings.maxFrameSize, 16384);
assert.strictEqual(settings.initialWindowSize, 256 * 1024);
assert.strictEqual(settings.maxFrameSize, 32 * 1024);

assert.strictEqual(binding.nghttp2ErrorString(-517),
'GOAWAY has already been sent');
Expand Down
Loading