coroutine function errors (Was: Openresty + cqueues)

quae · 2014-12-27T10:39:52+00:00

On Friday, 26 December 2014 19:57:31 UTC+2, rezc...@gmail.com wrote:Please note, if a templating language is the only reasonable solution that I would appre...

coroutine function errors (Was: Openresty + cqueues)

quae

On 26 December 2014 at 21:04, Yichun Zhang (agentzh) <age...@gmail.com> wrote:
> On Fri, Dec 26, 2014 at 5:32 PM, Daurnimator wrote:
>> The next problem I faced is actually a seperate one, and I should
>> probably fork the thread:
>>
>
> Yes, please.
>
>> Mixing coroutine functions results in strange errors: many functions
>> seem to not check their input well/correctly.
>>
>
> Well, feel free to create pull requests for ngx_lua :)

The changes I would make are perhaps a bit more structural than may be
accepted in a pull request.
Also I expect you do extensive bench-marking and other analysis on the codebase;
To ensure performance doesn't plummet, how do I run some
benchmarks/tests locally?

>> e.g, this causes a SIGABRT at
>> https://github.com/openresty/lua-nginx-module/blob/af16d1f99441b622188e91ef64dad61da024eae1/src/ngx_http_lua_util.c#L1052
>>
>>     local co = coroutine.create(function()
>>         coroutine._yield(10)
>
> Do you know that the coroutine._yield() thing is an intentionally
> undocumented internal API that is never supposed to be called by the
> users?

Yes, it is the original coroutine.yield.
I used it to demonstrate what some C function using lua_yield() does.

Perhaps you could do some trickery with the dynamic linker to get loaded
libraries to use `ngx_http_lua_coroutine_yield` and friends instead?

agentzh

Hello!

On Fri, Dec 26, 2014 at 6:39 PM, Daurnimator wrote:
> The changes I would make are perhaps a bit more structural than may be
> accepted in a pull request.

Pull requests are preferred.

> Also I expect you do extensive bench-marking and other analysis on the codebase;
> To ensure performance doesn't plummet, how do I run some
> benchmarks/tests locally?
>

Yes, Test::Nginx::Socket comes with a benchmark testing mode:

https://metacpan.org/pod/Test::Nginx::Socket#TEST_NGINX_BENCHMARK

> Yes, it is the original coroutine.yield.
> I used it to demonstrate what some C function using lua_yield() does.
>

This won't fly because ngx_lua comes with its own coroutine scheduler
(due to the limitation that the standard coroutine yield can only
yield one level up) and that was why we need a wrapper for the
standard coroutine API here in the first place.

> Perhaps you could do some trickery with the dynamic linker to get loaded
> libraries to use `ngx_http_lua_coroutine_yield` and friends instead?
>

Not really. Because this `ngx_http_lua_coroutine_yield` (or something
like that) will have to be a C function but you cannot yield across a
C function call boundary in either the standard Lua 5.1 interpreter or
in LuaJIT 2.0/2.1. So this won't fly either.

Regards,
-agentzh