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Code Issues Releases Wiki Activity

Rework traffic control to not involve UDP every SSL connection

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If the UDP monitor was busy, the SSL connections could back up.
Rework it so that the UDP monitor would get hung up by the SSL
process instead, if *any* of them get backed up.  However, the
nature of the loop in the SSL client is sufficiently lightweight
that it shouldn't hang up the UDP process under any reasonable
circumstance.  If it did hang it up though, it'll be less hung up
than discovery does already.
This commit is contained in:
Jarrod Johnson 2015-05-26 17:03:19 -04:00
parent f3bfa70f94
commit 5e248b0b0d
1 changed files with 24 additions and 35 deletions
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59
xCAT-server/sbin/xcatd
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@ -200,13 +200,8 @@ $xcatdir = (($tmp and $tmp->{value}) ? $tmp->{value} : "/etc/xcat");
$sitetab->close;
my $progname;
my $pipeexpected;
my $ssl2udppipe=0;
$SIG{PIPE} = sub {
if ($pipeexpected) { return; }
if ($ssl2udppipe) {
xCAT::MsgUtils->message("S","SIGPIPE xcatd SSL listener to udp service pipe is broken. Ignore this error if you are shutting down or restarting xcatd.");
return;
}
confess "SIGPIPE $$progname encountered a broken pipe (probably Ctrl-C by client)";
};
$progname = \$0;
@ -526,36 +521,29 @@ sleep 0.05; #up to 50 ms outage possible
}
}
sub update_udpcontext_from_sslctl {
my %args = @_;
my $udpcontext = $args{udpcontext};
my $select = $args{select};
my $msg;
eval { $msg = fd_retrieve($sslctl); };
if ($msg) {
#remember new count and, if new connection and we have a fudge factor, decrese fudge factor optimisticly assuming it's the right one
$udpcontext->{sslclientcount} = $msg->{sslclientcount};
if ($udpcontext->{clientfudge} and $msg->{clientcountchange} > 0) { $udpcontext->{clientfudge} -= $msg->{clientcountchange}; }
} else {
$select->remove($sslctl); close($sslctl); #something went horribly wrong
}
}
sub grant_tcrequests {
my $requestors = shift;
my $udpcontext = shift;
my $availableslots = $batchclients;
$availableslots -= $udpcontext->{clientfudge}; #value that forecasts the pressure
$availableslots -= $udpcontext->{sslclientcount}; #subtract all currently really active sessions
my $oldtime = time()-180; #drop requests older than three minutes if still around
my $msg;
eval { store_fd({'req'=>'get_client_count'}, $sslctl); $msg = fd_retrieve($sslctl); };
if (not $msg) {
return;
}
$availableslots -= $msg->{clientfudge}; #value that forecasts the pressure
$availableslots -= $msg->{sslclientcount}; #subtract all currently really active sessions
my $fudgefactor = $msg->{clientfudge};
foreach my $rkey (keys %{$requestors}) {
if ($requestors->{$rkey}->{timestamp} < $oldtime) { delete $requestors->{$rkey}; next; }
unless ($availableslots > 0) { next; } # no slots, ignore requests for now
$udpcontext->{clientfudge}+=1; #adjust forecast for being busy
$fudgefactor += 1; #adjust forecast for being busy
$availableslots-=1;
$udpcontext->{socket}->send("resourcerequest: ok\n",0,$requestors->{$rkey}->{sockaddr});
delete ($requestors->{$rkey}); #we acknoweldged, assume consumer got it, they'll do retry if they failed
}
eval { store_fd({'req'=>'set_fudge_factor', 'fudge'=>$fudgefactor}, $sslctl); $msg = fd_retrieve($sslctl); };
}
sub do_discovery_process {
@ -634,7 +622,6 @@ sub do_udp_service { #This function opens up a UDP port
my $discoctl = $args{discoctl};
$dispatch_requests=0;
my $udpcontext;
$udpcontext->{clientfudge}=0;
$udpcontext->{sslclientcount}=0;
my $udppidfile;
my $retry=1;
@ -750,8 +737,8 @@ sub do_udp_service { #This function opens up a UDP port
if ($hdl == $socket) {
$part = $socket->recv($data,1500);
$packets{$part} = [$part,$data];
} elsif ($hdl == $sslctl) {
update_udpcontext_from_sslctl(udpcontext=>$udpcontext,select=>$select);
#} elsif ($hdl == $sslctl) {
# update_udpcontext_from_sslctl(udpcontext=>$udpcontext,select=>$select);
}
}
}
@ -899,11 +886,6 @@ sub ssl_reaper {
close($udpctl); $udpctl=0;
}
}
if ($udpctl) {
$ssl2udppipe=1;
store_fd({clientcountchange=>$numdone,sslclientcount=>$sslclients},$udpctl); #notify udp service of how many clients are active
$ssl2udppipe=0;
}
$SIG{CHLD} = \&ssl_reaper;
}
@ -1116,6 +1098,7 @@ while (not $listener and $retry) {
sleep(0.05);
}
my $listenwatcher = IO::Select->new($listener);
my $udpwatcher = IO::Select->new($udpctl);
unless ($listener) {
kill 2, $pid_UDP;
@ -1144,6 +1127,7 @@ close($mainpidfile);
closelog();
my @pendingconnections;
my $tconn;
my $sslfudgefactor = 0;
until ($quit) {
$SIG{CHLD} = \&ssl_reaper; #set here to ensure that signal handler is not corrupted during loop
if (@pendingconnections) {
@ -1158,6 +1142,16 @@ until ($quit) {
push @pendingconnections,$tconn;
}
unless (scalar @pendingconnections) { next; } #if for some reason we landed here without any accepted connections, carry on..
while ($udpwatcher->can_read(0)) { # take an intermission to broker some state requests from udp traffic control
eval {
my $msg = fd_retrieve($udpctl);
if ($msg->{req} eq 'get_client_count') {
store_fd({'clientfudge'=>$sslfudgefactor, 'sslclientcount' => $sslclients});
} elsif ($msg->{req} eq 'set_fudge_factor') {
$sslfudgefactor = $msg->{fudge};
}
};
}
if ($sslclients > $maxsslclients) { #we have enough children, wait for some to exit before spawning more
$listenwatcher->can_read(0.1); #when next connection tries to come in or a tenth of a second, whichever comes first
next; #just keep pulling things off listen queue onto our own
@ -1268,11 +1262,6 @@ if ($inet6support) {
xexit(0);
}
$sslclients++; #THROTTLE
if ($udpctl) {
$ssl2udppipe=1;
store_fd({clientcountchange=>1,sslclientcount=>$sslclients},$udpctl); #notify udp service of how many clients are active
$ssl2udppipe=0;
}
$cnnection->close();
}
if (open($mainpidfile,"<","/var/run/xcat/mainservice.pid")) {