[Zope] Re: WHY ? -- Performace in serving large media filesfrom ZODB vs from external file system

[Toby Dickenson]

On Sat, 7 Jul 2001 13:22:49 +0300, "Sedat Yilmazer" <sedat@kibele.com>
wrote:

> setting up the client/server connection + (How is it in ZServer forks? =
)=20

These two steps happen consecutively:

> request processing + =20
> finding the object in ZODB +=20

However these are interleaved to a certain extent:

> Reading the object from ZODB +
> writing the data to temp file +=20
> pushing the file to client

The total latency before the client recieves the *first* byte is:

in the worker thread:
* request processing
* finding the object
* reading the first 64k (iirc) chunk from ZODB
* writing that chunk to a temp file via RESPONSE.write
then back in the main medusa thread:
* reading it back from the temp file
* pushing it over the socket
* network latency

Im not sure how much bouncing via the filesystem affects the total
latency for the first byte..


In the majority of cases the time to recieve the *last* byte is given
by network bandwidth not server performance, as you suggest.



Toby Dickenson
tdickenson@geminidataloggers.com