async_hooks: destroy emitted more than once for an asyncId

[Trott]

• Version: 12.0.0-pre (current master)
• Platform: Darwin LIB-0F7FVH8-LT 18.2.0 Darwin Kernel Version 18.2.0: Thu Dec 20 20:46:53 PST 2018; root:xnu-4903.241.1~1/RELEASE_X86_64 x86_64
• Subsystem: async_hooks

This code shows destroy emitting twice for a single asyncId. (You may need to run it more than once to see the error and/or increase the value of N in the code, but it repros most of the time for me.)

'use strict';

const assert = require('assert');
const async_hooks = require('async_hooks');
const http = require('http');

const N = 50;
const KEEP_ALIVE = 100;

const destroyedIds = [];
async_hooks.createHook({
  destroy: (asyncId) => {
    assert(!destroyedIds.includes(asyncId), `${asyncId} already in ${destroyedIds.sort()}`);
    destroyedIds.push(asyncId);
  }
}).enable();

const server = http.createServer(function(req, res) {
  res.end('Hello');
});

const keepAliveAgent = new http.Agent({
  keepAlive: true,
  keepAliveMsecs: KEEP_ALIVE,
});

let M = 0;
server.listen(0, function() {
  for (let i = 0; i < N; ++i) {
    (function makeRequest() {
      http.get({
        port: server.address().port,
        agent: keepAliveAgent
      }, function(res) {
        res.resume();
        M++;
        if (M === N)
          server.close();
        assert.ok(M <= N);
      });
    })();
  }
});

[Trott]

@nodejs/async_hooks

[BridgeAR]

I am able to reproduce the error and it seems this always fails with the identical asyncId which is a bit surprising. Init is definitely only called once for the id.

[Flarna]

I expect this is related to reusing HTTPPARSER instances; so maybe #25094 fixes this as side effect.

By increasing N I can reproduce this also with 8, 10 and 11.

[Flarna]

I think destroy gets once triggered via Parser::Free() and once again in Parser::Reinitialize() which calls AsyncWrap::AsyncReset().

[Flarna]

Seems #25094 didn't fix this but the behaviour is different. I think the problem now is that destroy is called only once during Parser::Free() but init is missing once a Parser gets reused.

[Flarna]

This issue happens also on Node 10 and 8.
Fix #27477 depends on #25094 which is labeled with dont-land-on-v10.x therefore the fix can't be backported as is to v10.
Should I create a dedicated PR to fix this on v10 and v8?

[Trott]

This issue happens also on Node 10 and 8.
Fix #27477 depends on #25094 which is labeled with dont-land-on-v10.x therefore the fix can't be backported as is to v10.
Should I create a dedicated PR to fix this on v10 and v8?

@mcollina is the person who thought #25094 should not land on v10.x. Pinging them to make sure that's still their view. If you can find a way to fix it that avoids whatever their concerns about landing that PR on v10.x were, then yes!

[Trott]

(Also, thanks for being on top of this stuff!)