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Correct statement about select on windows

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Ryan Dahl 2011-03-30 12:15:54 -07:00
parent 336a768a21
commit 1c15142618
1 changed files with 15 additions and 10 deletions
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iocp-links.html
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@ -46,15 +46,20 @@
is done in Unix.
<p>Windows presents asynchronous and non-blocking I/O differently than in Unix.
The syscall <code>select()</code> is available in Windows but it
supports only 64 file descriptors&mdash;which is unacceptable for
high-concurrency servers. Instead a system called <a
href="http://msdn.microsoft.com/en-us/library/ms686358(v=vs.85).aspx">overlapped
I/O</a> is used. <a
href="http://msdn.microsoft.com/en-us/library/aa365198(VS.85).aspx">I/O
completion ports</a> (IOCPs) are the objects used to poll overlapped I/O
for completion.
IOCPs are similar to the Unix I/O multiplexers
The syscall
<a href="http://msdn.microsoft.com/en-us/library/ms740141(v=VS.85).aspx"><code>select()</code>
is available in Windows</a>.
<code>select</code> processing is O(n) in the number of file descriptors
unlike the modern constant-time multiplexers like epoll which makes it
unacceptable for high-concurrency servers.
<p>
Windows has another way of polling called
<a href="http://msdn.microsoft.com/en-us/library/aa365198(VS.85).aspx">I/O completion ports</a>
(IOCPs). IOCPs are the objects used to poll
<a href="http://msdn.microsoft.com/en-us/library/ms686358(v=vs.85).aspx">overlapped I/O</a>
for completion. IOCP polling is constant time (REF?).
They are similar to the Unix I/O multiplexers
<ul>
<li> <a
href="http://en.wikipedia.org/wiki/Kqueue">kqueue</a> on Macintosh and
@ -536,7 +541,7 @@ IOCP:
&mdash; an async <code>sendfile()</code> for windows.
<li><a href="http://msdn.microsoft.com/en-us/library/ms741565(v=VS.85).aspx"><code>WSADuplicateSocket()</code></a>
&mdash; describes how to share a socket between two processes.
<li><a href="http://msdn.microsoft.com/en-us/library/6e3b887c.aspx"><code>_setmaxstdio()</code></a>
<li id="setmaxstdio"><a href="http://msdn.microsoft.com/en-us/library/6e3b887c.aspx"><code>_setmaxstdio()</code></a>
&mdash; something like setting the maximum number of file decriptors
and <a
href="http://www.kernel.org/doc/man-pages/online/pages/man2/setrlimit.2.html"><code>setrlimit(3)</code></a>