Akins, Brian wrote:
On 9/1/08 8:11 AM, "Jim Jagielski" <[EMAIL PROTECTED]> wrote:
On Aug 31, 2008, at 9:49 AM, Bing Swen wrote:
To my knowledge, the "one thread per connection" network i/o model
is a
suboptimal use
threads vs. events is certainly not, imo, a finalized debate
yet with a known winner or loser. Maybe 5-10 years ago events
had a "clear" advantage but today that is hardly the case...
I have documented my vote on this in the past, but the "async is inherently
faster" looks good on paper, but does not, IMNSHO, measure up in the real
world.
I completely agree, it's not a slam-dunk conclusion that async/event
driven connection management in an http server is clearly superior.
However, Bing mentioned Windows... Apache on Windows is not a stellar
performer, especially compared to a server that fully exploits IOCPs,
connection reuse and TransmitFile. The Windows MPM does use IOCPs (not
optimally) and connection reuse. The biggest inhibitor to Apache on
Windows performance serving files is in the apr_sendfile implementation.
Calls to TransmitFile are broken into something like 64KB chunks in
order to facilitate detecting send timeouts. If you modify the call to
TransmitFile to always just send the whole file, performance sending
large files will improve dramatically.
There is also a difference between async i/o and event driven i/o. The
former requires more discipline managing buffers across the async i/o
calls. Windows supports true async network i/o; many unix distros do
not. IMO, event driven is good enough. async introduces too much
complexity for questionable benefit.
Bill
