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
> http://mailman.nginx.org/mailman/listinfo/nginx-devel

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