nginx eval with memc set command very slowly

[agentzh]

On Tue, Mar 9, 2010 at 10:52 AM, agentzh <agentzh at gmail.com> wrote:
> On Mon, Mar 8, 2010 at 4:30 PM, yaoxinming <yaoxinming at gmail.com> wrote:
>> when use eval with memc  set(all dev by agentzh ) ,I feel the response is
>> very slowly,but get is very quickly,below is the configue
>>
>
> I'm guessing that it's caused by the "201 Created" status returned by
> the ngx_memc set command. According to the source of ngx_eval, it only
> accepts "200 OK". So in case of 201, it simply returns NGX_DECLINED,
> which *may* produce that hang.
>

I've reproduced this hang on my side and spent half of my day tracking
this issue. But it looked deeper than I had expected.

Using subrequests issued by echo_location and echo_location_async does
not trigger this hang, but "eval" does. I'm now guessing it has
something to do with subrequests issued from the rewrite phase because
the ngx_echo module starts subrequests in content handlers only.

I don't have enough time to track this further for now. Will get back
to this issue some time later. Sorry.

Cheers,
-agentzh