I know this configuration variable. It has been added by Maxim last
mouth in unstable (as i remembered but I am not absolutely sure). It
seem to be a workaround and will not solve the problem. I think it is
unusable.

If we use it for the same case:
In first 1 second A receives 1000 requests. Only 1 request will be send
to B, for first request that A receives. The others 999 will wait for
example 5 seconds. The link btw A and B is 1 MB per second and for 5
seconds A may receive 5 MB of data, so after 5 seconds 999 requests will
be sent to B.

Is it right?


On 01/12/2012 11:33 AM, Andrew Alexeev wrote:
> Check this one, pls :)
> http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_lock
>
> On Jan 12, 2012, at 1:32 PM, Anatoli Marinov wrote:
>
>> Hello Colleagues,
>>
>> I found a performance issue with proxy_cache module.
>>
>>
>> For example I have installed 2 servers with nginx-1.0.10. First
>> one(A) works as a reverse proxy and the second one(B) is a storage
>> with many big files – 1GB – 2GB.
>>
>> The link between A and B for example may serve 1 MBps.
>>
>>
>> There is a new object on B and it is not yet cached on A.
>>
>> Let we assume this is a hot new object and A receives 1000 requests
>> for 3 seconds for it. Because the object is not cached the requests
>> will pass through upstream to B and incoming 1000 streams will be
>> saved on A in tmp directory as a separate files. After every request
>> has completed the files from tmp directory will be moved to cache
>> directory. 1000 equal operations for one and the same object. In
>> addition every object will be cached slow because there are 999 other
>> streams.
>>
>>
>> This 1 GB object will be downloaded 1000 times before it may be
>> cached and this is not optimal at all.
>>
>>
>> Am I missing something? It may be my configuration issue?
>>
>> Is there a solution for that?
>>
>> Cheers
>> Anatoli Marinov
>>
>> _______________________________________________
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>> nginx-devel@nginx.org <mailto:nginx-devel@nginx.org>
>> http://mailman.nginx.org/mailman/listinfo/nginx-devel
>
>
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