mirror of https://gitee.com/openkylin/nodejs.git
66 lines
2.1 KiB
JavaScript
66 lines
2.1 KiB
JavaScript
'use strict';
|
|
|
|
// Test to validate massive dns lookups do not block filesytem I/O
|
|
// (or any fast I/O). Prior to https://github.com/libuv/libuv/pull/1845
|
|
// few back-to-back dns lookups were sufficient to engage libuv
|
|
// threadpool workers in a blocking manner, throttling other work items
|
|
// that need pool resources. Start slow and fast I/Os together, make sure
|
|
// fast I/O can complete in at least in 1/100th of time for slow I/O.
|
|
// TEST TIME TO COMPLETION: ~5 seconds.
|
|
|
|
const common = require('../common');
|
|
const dns = require('dns');
|
|
const fs = require('fs');
|
|
const assert = require('assert');
|
|
|
|
const start = Date.now();
|
|
|
|
const slowIOmax = 100;
|
|
let slowIOcount = 0;
|
|
let fastIOdone = false;
|
|
let slowIOend, fastIOend;
|
|
|
|
function onResolve() {
|
|
slowIOcount++;
|
|
if (slowIOcount === slowIOmax) {
|
|
slowIOend = Date.now();
|
|
|
|
// Conservative expectation: finish disc I/O
|
|
// at least by when the net I/O completes.
|
|
assert.ok(fastIOdone,
|
|
'fast I/O was throttled due to threadpool congestion.');
|
|
|
|
// More realistic expectation: finish disc I/O at least within
|
|
// a time duration that is half of net I/O.
|
|
// Ideally the slow I/O should not affect the fast I/O as those
|
|
// have two different thread-pool buckets. However, this could be
|
|
// highly load / platform dependent, so don't be very greedy.
|
|
const fastIOtime = fastIOend - start;
|
|
const slowIOtime = slowIOend - start;
|
|
const expectedMax = slowIOtime / 2;
|
|
assert.ok(fastIOtime < expectedMax,
|
|
'fast I/O took longer to complete, ' +
|
|
`actual: ${fastIOtime}, expected: ${expectedMax}`);
|
|
}
|
|
}
|
|
|
|
|
|
for (let i = 0; i < slowIOmax; i++) {
|
|
// We need to refresh the domain string everytime,
|
|
// otherwise the TCP stack that cache the previous lookup
|
|
// returns result from memory, breaking all our Math.
|
|
dns.lookup(`${randomDomain()}.com`, {}, common.mustCall(onResolve));
|
|
}
|
|
|
|
fs.readFile(__filename, common.mustCall(() => {
|
|
fastIOend = Date.now();
|
|
fastIOdone = true;
|
|
}));
|
|
|
|
function randomDomain() {
|
|
const d = Buffer.alloc(10);
|
|
for (let i = 0; i < 10; i++)
|
|
d[i] = 97 + (Math.round(Math.random() * 13247)) % 26;
|
|
return d.toString();
|
|
}
|