nginx and event ports

[johngrasty]

So yesterday, I was alerted to an nginx process using 100% of a core. dtrace revealed that it was making tens of thousands of calls to ioctl. (Here's the output for anyone curious.) dtrace further revealed that the argument for ioctl was /dev/poll. I thought this strange since event ports is newer and well regarded. The nginx documents show this as a valid option ("Connection processing methods" page and the "use" directive doc). The latter specifically states that nginx will use the most efficient. A quick test revealed that adding the use eventports; to the config file does enable event ports:

events {
    worker_connections  1024;
    **use eventports;**
}

Further research indicates that the reason isn't selected automatically is that there are problems with the implementation—particularly when used with the proxy module.

Here is a short thread from 2013 where the developers mention (with no details) the problem.

Here's another thread where someone gives more detail on reproducing the issue.

Here is a proposed patch, but there was no discussion.

I thought I had a repeatable test to make this fail, but I'm not so sure now. Just in tests on my lan, I would occasionally see errors. I really don't know if this is related though. Here's an example:

2015/09/07 11:54:01 [alert] 76529#0: *34 port_dissociate() failed (2: No such file or directory) while reading upstream, client: 10.0.0.202, server: , request: "GET /download/100MB-newark.bin HTTP/1.1", upstream: "http://127.0.0.1:9000/download/100MB-newark.bin", host: "10.0.0.64"

There was a fairly recent commit that touched the event port module, but I have no idea what it did, and there weren't any details in the changelog. (changeset)

I'm willing to help any way possible, but I don't know that much! :-D

[mamash]

Erroneous auto-close.