Cannot read property 'asyncReset' of null

[zkd8907]

• Version: 8.0.0
• Platform: Linux x64

We deployed Node 8.0 on our servers, but found an error when a large number of concurrent requests came.

Stack:

TypeError: Cannot read property 'asyncReset' of null
    at Agent.addRequest (_http_agent.js:170:19)
    at new ClientRequest (_http_client.js:271:16)
    at Object.request (http.js:39:10)

I checked the source file _http_agent.js. Line 170 is socket._handle.asyncReset();. I think it's better to check whehter socket._handle is null before use.

[AndreasMadsen]

You are most likely using a custom agent somewhere in your code. Any change you could check for that? We would always like to understand the cause of the error, rather than just making a blind fix. Preventing asyncReset() from being called by checking socket._handle may cause other issues.

/cc @nodejs/async_hooks

[trevnorris]

@AndreasMadsen Unfortunately I haven't found a better approach than to check if socket._handle exists in the case of passing a custom Agent. We have to do something similar in lib/timers.js because custom timer objects can be passed in (and we do that quite a bit in core)`.

Though we may be able to get around this using a combination of my final proposal at the bottom of #13548 (comment) and what we do in lib/timers.js. Which is we assign a new asyncId to the custom object on async_id_symbol and use that. It may have a strange timing issue about when to run init() but I think that's something we can get around.

[mnutt]

I'm seeing the same error, while using an instantiated agent:

const agent = new http.Agent({
  keepAlive: true,
  maxSockets: 128,
  maxFreeSockets: 64
});

http.request({agent, ....});

Would we see a difference in this approach vs just modifying the limits of the default global agent?

[refack]

I'm seeing the same error, while using an instantiated agent:

@mnutt we've been rolling patches around this area during the last month (#13348, #13092, and soon #14026 and #13839). Are you still seeing this error in node@8.1.3?

[mnutt]

Sorry, I should have mentioned that yes, it was node 8.1.3.

[adiulici]

I'm seeing the same issue on node v8.1.14. Unfortunately it's being thrown inside a dependency (new relic) so I cannot offer much of a detail.

[AndreasMadsen]

@aashil could you try the nightly build, most of the async_hooks fixes are in v8.2.0 which hasn't been released yet (#13744).

[adiulici]

@AndreasMadsen Unfortunately I only see this on my production environment when the number of concurrent users is high, and I can't put a nightly build on it..

[refack]

@adiulici node@8.2.0 was just released some relevant bug fixes are in it. If you are comfortable you could try it.

[rwlaschin]

HI. I'm seeing this issue as well 8.1.4

I'm using a custom agent
const keepAliveAgent = new http.Agent({ keepAlive: true });

I'll try 8.2.0 and see if the issue is resolved.

[rwlaschin]

Unfortunately, no it still happens

2017-07-20T11:31:56-0700 <error> RouteLoader.js:60 () message Cannot read property 'asyncReset' of null error TypeError: Cannot read property 'asyncReset' of null
    at Agent.addRequest (_http_agent.js:171:19)
    at new ClientRequest (_http_client.js:272:16)
    at Object.request (http.js:39:10)
    at Request.send (/Users/robert/Repositories/ry-openrtb-exchange/rtbexchange/server/modules/Bid/Request.js:88:11)
    at /Users/robert/Repositories/ry-openrtb-exchange/rtbexchange/server/modules/Dsp/Manager.js:172:29
    at Utilities.ProcessorRunner.completefn (/Users/robert/Repositories/ry-openrtb-exchange/rtbexchange/server/interfaces/Utilities.js:147:9)
    at /Users/robert/Repositories/ry-openrtb-exchange/rtbexchange/node_modules/async/internal/once.js:12:16
    at iteratorCallback (/Users/robert/Repositories/ry-openrtb-exchange/rtbexchange/node_modules/async/eachOf.js:60:13)
    at /Users/robert/Repositories/ry-openrtb-exchange/rtbexchange/node_modules/async/internal/onlyOnce.js:12:16

It is very frequent.

_{edit trevnorris: place output in code block}

[rwlaschin]

I did not see it when I changed back to version 7.10.1, it was in all the versions of 8.. that I tried.

I don't believe I saw this error until I added node-redis, I'm not sure if that is a red-herring or not.

[trevnorris]

Sorry for the delay. See the issue. I'll write up a fix tonight.

[refack]

I did not see it when I changed back to version 7.10.1, it was in all the versions of 8.. that I tried.

I don't believe I saw this error until I added node-redis, I'm not sure if that is a red-herring or not.

So for context: node v8 added a new layer of tracing (i.e. Async Hooks). This layer is active even if the user does not use it, to enable ad hoc interrogating the system state.
Although this new layer has been meticulously designed and tested, there are a few open edge cases (one of them is custom implementations of HTTP Agent).
node@8.2.0 included several bug fixes in this layer (node@8.2.1 was fast tracked, and we managed to release it 1 day after 8.2.0 to solve two new bugs in Async Hooks). Meanwhile we converged on a design change that should minimize (hopefully eliminate) errors experienced by users who don't actually activate the Async Hooks.
Thank you for your patience, and your support by reporting these issues! 🎩

[trevnorris]

Fix at #14419.

[SoumyaDey1994]

Hi,

Is there any workaround to ignore this issue in version 8.1.x? Our production environment is having version 8.1.x and migrating it to a higher version may cause other implications in our codebase.

Please suggest a remedy for version 8.1.x. Thanks in advance.