Re: non-blocking I/O

From: Dancer <>
Date: Thu, 08 Apr 1999 18:09:05 +1000

> klan wrote:
> ============
> says
> Squid offers high performance proxy caching for Web clients, It
> supports FTP, Gopher, and HTTP requests. The cache
> software, available only in source, is relatively fast because it
> never needs to fork, is implemented with non-blocking I/O,
> keeps meta data and hot objects in VM, and caches DNS
> lookups. Squid caches can be arranged hierarchically for an
> improvement in response times and a reduction in bandwith
> usage. Squid runs on all popular Unix platforms.
> ===============
> From the above, What's non-blocking I/O mean?

Simple explanation: I/O that doesn't block.
Very simple explanation: Most I/O operations 'block' an application
(that is, it puts them on hold until the operation is complete).
Non-blocking operations (also called 'asynchronous') do not put the
program on hold, but the program must be careful that it can keep track
of them. A program that can effectively track and use non-blocking I/O
operations is _considerably_ more responsive than one that cannot.

Received on Thu Apr 08 1999 - 02:08:14 MDT

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