socket close: graceful shutdown vs. lingering (eternal TIME_WAIT issue) #14
Comments
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Revisited that... first attempt to fix is partially successful (fewer TIME_WAITs now, but they are still there sporadically), must investigate deeper... test code ...proc log args {}
proc get_tw_count {port} {
regexp -all [regsub {@port} {:@port\M[^\n]+TIME_WAIT} $port] [exec netstat -n]
}
proc test {port} {
puts [string repeat -- 20]\t[get_tw_count $port]
timerate {
puts [timerate {
close [set ch [socket 127.0.0.1 $port]]
log C-closed-cli:\t$ch
} 2000 50]
after 100; puts [string repeat -- 20]\t[get_tw_count $port]
} 2000
}
proc test_server {port onConnect} {
package require Thread
thread::send -async [set th [thread::create]] [list proc log args [info body log]]
thread::send -async $th [list proc onConnect {ch args} $onConnect]
thread::send -async $th [list set port $port]
thread::send $th { set srv [socket -server onConnect $port] }
test $port
thread::send $th {close $srv; thread::release}
}
puts "================== extern (web-server) =============="
test 80
puts "================== simple-close ====================="
test_server 8055 {
log S-close-srv:\t$ch; close $ch; log S-closed:\t$ch
}
puts "================== proper-close ====================="
test_server 8055 {
chan event $ch readable [list apply {{ch} {
if {[catch {string length [read $ch 1024]} s] || $s == 0} {
log S-close-srv:\t$ch; close $ch; log S-closed:\t$ch
}
}} $ch]
} |
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Fixed (well there are some TIME_WAIT still remaining sporadically, but the "flood" is completely gone)... before (not fixed, ca. 1500 handles in TIME_WAIT) ...after (fixed, 0 handles in TIME_WAIT) ...I'll make a small review and hereafter a PR here. |
sebres
added a commit
to sebres/tcl-iocp
that referenced
this issue
Jan 25, 2021
…wn vs. lingering (eternal TIME_WAIT issue); back-ported [b960d1b71e] from tcl-repo, adjusted for IOCP, provides asynchronous close in helper thread (after completion) if pending operations available
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Package seems to be affected by same issue as Tcl - [b6d0d8cc2c]:
results to this:
% set port 80; stats 0 % timerate { time { close [socket localhost $port] } 50; after 100; stats } 50 100 150 200 250This test and test in next comment expecting replacement for
socketwith::iocp::inet::socketor following inject for every interpreter (thread) used in test:May be similar fix like [b960d1b71e] or some option (like
-linger) can be implemented to avoid such TIME-WAIT floods.Or even both, so
-linger automay be set as default, so decision whether lingering or graceful shutdown is expected can follow the implementation like [b960d1b71e].The text was updated successfully, but these errors were encountered: