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perf(http2): avoid isArray checks for common headers #5170

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Merged
mcollina merged 2 commits into from
May 5, 2026
Merged

perf(http2): avoid isArray checks for common headers #5170

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30692bc
perf(http2): avoid isArray checks for common headers
trivikr May 2, 2026
2c649bc
Merge branch 'nodejs:main' into h2-reduce-header-building-overhead
trivikr May 4, 2026
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53 changes: 28 additions & 25 deletions lib/dispatcher/client-h2.js
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Original file line number Diff line number Diff line change
Expand Up @@ -538,47 +538,50 @@ function shouldSendContentLength (method) {
return method !== 'GET' && method !== 'HEAD' && method !== 'OPTIONS' && method !== 'TRACE' && method !== 'CONNECT'
}

function writeH2 (client, request) {
const requestTimeout = request.bodyTimeout ?? client[kBodyTimeout]
const session = client[kHTTP2Session]
const { method, path, host, upgrade, expectContinue, signal, protocol, headers: reqHeaders } = request
let { body } = request

if (upgrade != null && upgrade !== 'websocket') {
util.errorRequest(client, request, new InvalidArgumentError(`Custom upgrade "${upgrade}" not supported over HTTP/2`))
return false
}

function buildRequestHeaders (reqHeaders) {
const headers = {}

for (let n = 0; n < reqHeaders.length; n += 2) {
const key = reqHeaders[n + 0]
const val = reqHeaders[n + 1]
const current = headers[key]

if (key === 'cookie') {
if (headers[key] != null) {
headers[key] = Array.isArray(headers[key]) ? (headers[key].push(val), headers[key]) : [headers[key], val]
if (current != null) {
headers[key] = Array.isArray(current) ? (current.push(val), current) : [current, val]
} else {
headers[key] = val
}

continue
}

if (Array.isArray(val)) {
for (let i = 0; i < val.length; i++) {
if (headers[key]) {
headers[key] += `, ${val[i]}`
} else {
headers[key] = val[i]
}
}
} else if (headers[key]) {
headers[key] += `, ${val}`
} else {
headers[key] = val
if (typeof val === 'string') {
headers[key] = current ? `${current}, ${val}` : val
continue
}

for (let i = 0; i < val.length; i++) {
headers[key] = headers[key] ? `${headers[key]}, ${val[i]}` : val[i]
}
}

return headers
}

function writeH2 (client, request) {
const requestTimeout = request.bodyTimeout ?? client[kBodyTimeout]
const session = client[kHTTP2Session]
const { method, path, host, upgrade, expectContinue, signal, protocol, headers: reqHeaders } = request
let { body } = request

if (upgrade != null && upgrade !== 'websocket') {
util.errorRequest(client, request, new InvalidArgumentError(`Custom upgrade "${upgrade}" not supported over HTTP/2`))
return false
}

const headers = buildRequestHeaders(reqHeaders)

/** @type {import('node:http2').ClientHttp2Stream} */
let stream = null

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