ngx.exit vs ngx.status return

pavel.zhuk · 2015-09-23T17:03:41+00:00

Hello! On Thu, Oct 8, 2015 at 5:23 PM, 杨阳 <yang...@upai.com> wrote: > when use userspace, it seems ok, Yeah, the user space C land f...

ngx.exit vs ngx.status return

pavel.zhuk

Hello,

I was recently troubleshooting high latency resposne for one of my HTTPS endpoints.

Testing leads me to the piece of code which was just doing

ngx.exit(ngx.HTTP_FORBIDDEN)

So I had just replaced it with

ngx.status = ngx.HTTP_FORBIDDEN

return

Latency has dropped significantly, from 500-600ms to 80-120ms.

So I am wondering what is the principal differences between these two behaviors?

Is there any configuration parameters which might affect performance of ngx.exit comaring to ngx.status ?

We are using latest openresty version, with lua-resty-kafka and lua-resty-redis.

Appreciate any feedback.

Thanks

doujiang24

Hello,

which version of lua-resty-kafka are you using? Some old version may increased latency

You are recommended to use the last version v0.05 :)

Or can you show a little sample code ?

2015-09-23 17:03 GMT+08:00 Pavlo Zhuk <pave...@gmail.com>:

Hello,

I was recently troubleshooting high latency resposne for one of my HTTPS endpoints.
Testing leads me to the piece of code which was just doing

ngx.exit(ngx.HTTP_FORBIDDEN)

So I had just replaced it with

ngx.status = ngx.HTTP_FORBIDDEN
return

Latency has dropped significantly, from 500-600ms to 80-120ms.

So I am wondering what is the principal differences between these two behaviors?
Is there any configuration parameters which might affect performance of ngx.exit comaring to ngx.status ?

We are using latest openresty version, with lua-resty-kafka and lua-resty-redis.

Appreciate any feedback.

Thanks

.

pavel.zhuk

Hi,

Thanks for reply.

Our openresty build includes very latest changes from lua-resty-kafka repo.
Last commit: https://github.com/doujiang24/lua-resty-kafka/tree/1995aa44f5a9fd8996f809ce1d470528f5f4620d

I have inserted a piece our of code in this gist https://gist.github.com/pzhuk/1f51a9872ae4e15583eb

Basically it's a helper which is collected via _M.log method from downstream HTTP request handler

Appreciate any feedback on the code. Thanks!

BR, Pavel V. Zhuk

2015-09-24 16:23 GMT+03:00 DeJiang Zhu <douj...@gmail.com>:

Hello,

which version of lua-resty-kafka are you using? Some old version may increased latency
You are recommended to use the last version v0.05 :)

Or can you show a little sample code ?

2015-09-23 17:03 GMT+08:00 Pavlo Zhuk <pave...@gmail.com>:
Hello,

I was recently troubleshooting high latency resposne for one of my HTTPS endpoints.
Testing leads me to the piece of code which was just doing

ngx.exit(ngx.HTTP_FORBIDDEN)

So I had just replaced it with

ngx.status = ngx.HTTP_FORBIDDEN
return

Latency has dropped significantly, from 500-600ms to 80-120ms.

So I am wondering what is the principal differences between these two behaviors?
Is there any configuration parameters which might affect performance of ngx.exit comaring to ngx.status ?

We are using latest openresty version, with lua-resty-kafka and lua-resty-redis.

Appreciate any feedback.

Thanks

.

doujiang24

Hello,

Yeah, the lua-resty-kafka you are using should be fine.

produce:send just push data to ringbuffer(Lua table) and data will be really flush to kakfa in background thread create by ngx.timer.at

Do you mean change at line 74 or line 81?

If is line 74, seems there is nothing to do with lua-resty-kafka

Or can you show a minimize example that others can reproduce it?

2015-09-25 0:06 GMT+08:00 Pavel V. Zhuk <pave...@gmail.com>:

Hi,

Thanks for reply.
Our openresty build includes very latest changes from lua-resty-kafka repo.
Last commit: https://github.com/doujiang24/lua-resty-kafka/tree/1995aa44f5a9fd8996f809ce1d470528f5f4620d

I have inserted a piece our of code in this gist https://gist.github.com/pzhuk/1f51a9872ae4e15583eb
Basically it's a helper which is collected via _M.log method from downstream HTTP request handler

Appreciate any feedback on the code. Thanks!

BR, Pavel V. Zhuk

2015-09-24 16:23 GMT+03:00 DeJiang Zhu <douj...@gmail.com>:
Hello,

which version of lua-resty-kafka are you using? Some old version may increased latency
You are recommended to use the last version v0.05 :)

Or can you show a little sample code ?

2015-09-23 17:03 GMT+08:00 Pavlo Zhuk <pave...@gmail.com>:
Hello,

I was recently troubleshooting high latency resposne for one of my HTTPS endpoints.
Testing leads me to the piece of code which was just doing

ngx.exit(ngx.HTTP_FORBIDDEN)

So I had just replaced it with

ngx.status = ngx.HTTP_FORBIDDEN
return

Latency has dropped significantly, from 500-600ms to 80-120ms.

So I am wondering what is the principal differences between these two behaviors?
Is there any configuration parameters which might affect performance of ngx.exit comaring to ngx.status ?

We are using latest openresty version, with lua-resty-kafka and lua-resty-redis.

Appreciate any feedback.

Thanks

.

agentzh

Hello!

On Wed, Sep 23, 2015 at 5:03 PM, Pavlo Zhuk wrote:
> I was recently troubleshooting high latency resposne for one of my HTTPS
> endpoints.
> Testing leads me to the piece of code which was just doing
>
> ngx.exit(ngx.HTTP_FORBIDDEN)
>
> So I had just replaced it with
>
> ngx.status = ngx.HTTP_FORBIDDEN
> return
>
> Latency has dropped significantly, from 500-600ms to 80-120ms.

I'm surprised that these two different lines can make such a dramatic
difference in performance. Maybe it's just triggering something else
in your code base. Is it CPU bound? If yes, then plotting an on-CPU
flame graph can give us some insights about what is really going on
here. Please see

    https://openresty.org/#Profiling

Failing that, as DeJiang says, providing a minimal and standalone
example can be very helpful.

Regards,
-agentzh