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<!-- Presentation generated by Internet Assistant for Microsoft PowerPoint 97 -->
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<TITLE>Example: Event-Driven vs Thread I/O</TITLE>
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<P>Slide 21 of 77</P>
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<!-- <UL>
<H2>Example: Event-Driven vs Thread I/O</H2>
</UL></P>
<P><UL>
<LI><H2>I/O bound apps are sometimes easier with threads:</H2>
</UL></P>
<P><UL>
global done count
</UL><UL>
</UL><UL>
proc my.read {sock} {
</UL><UL>
global done count
</UL><UL>
read $sock
</UL><UL>
if [eof $sock] {
</UL><UL>
close $sock
</UL><UL>
if {[incr count -1] == 0} {
</UL><UL>
set done 1
</UL><UL>
}
</UL><UL>
}
</UL><UL>
}
</UL><UL>
</UL><UL>
proc my.write {sock} {
</UL><UL>
puts $sock "GET /index.html\r\n"
</UL><UL>
flush $sock
</UL><UL>
fileevent $sock readable "my.read $sock"
</UL><UL>
}
</UL><UL>
</UL><UL>
set count 0
</UL><UL>
foreach host { host1 host2 host3 host4} {
</UL><UL>
incr count
</UL><UL>
set sock [socket -async $host 80]
</UL><UL>
fconfigure $sock -blocking off
</UL><UL>
fileevent $sock writable "my.write $sock"
</UL><UL>
}
</UL><UL>
</UL><UL>
vwait done</UL></P>
<P><UL>
proc my.thread {host} {
</UL><UL>
set sock [socket $host 80]
</UL><UL>
puts $sock "GET /index.html\r\n"
</UL><UL>
flush $sock
</UL><UL>
read $sock
</UL><UL>
close $sock
</UL><UL>
}
</UL><UL>
</UL><UL>
foreach host {host1 host2 host3 host4} {
</UL><UL>
lappend tids [ns_thread begin my.thread $host"]
</UL><UL>
}
</UL><UL>
</UL><UL>
foreach tid $tids {
</UL><UL>
ns_thread wait $tid
</UL><UL>
}</UL></P>
<P><UL>
Events</UL></P>
<P><UL>
Threads</UL></P>
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