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UDT: Improve performance by relying on a single ticker instead of creating new ones for ACK/NAK each outgoing packet.

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Creating new tickers was huge stress for the gc reducing performance (according to pprof 35% was spent on runtime.siftdownTimer).
This commit is contained in:
Kleissner
2022-01-17 04:28:39 +01:00
parent f305e5b158
commit 1af98ab141
1 changed files with 9 additions and 37 deletions
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46
udt/udtsocket_recv.go
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@@ -29,8 +29,6 @@ type udtSocketRecv struct {
recvPktHistory []time.Duration // list of recently received packets.
recvPktPairHistory []time.Duration // probing packet window.
ackLinkInfoSent time.Time // when link info was sent in ACK packet last time
resendNAKTimer <-chan time.Time // Timer for resending outgoing NAK
resendNAKTicker time.Ticker // Ticker for resending outgoing NAK
resendACKTimer <-chan time.Time // Timer for resending outgoing ACK
resendACKTicker time.Ticker // Ticker for resending outgoing ACK
}
@@ -45,10 +43,14 @@ func newUdtSocketRecv(s *udtSocket) *udtSocketRecv {
recvPktPend: createPacketHeap(),
recvLossList: createPacketIDHeap(),
ackHistory: createHistoryHeap(),
resendNAKTimer: make(chan time.Time),
resendACKTimer: make(chan time.Time),
}
go sr.goReceiveEvent()
// set the timer for constantly resending ACKs for the highest sequence ID and NAKs for missing packets
sr.resendACKTicker = *time.NewTicker(s.Config.SynTime)
sr.resendACKTimer = sr.resendACKTicker.C
return sr
}
@@ -79,24 +81,14 @@ func (s *udtSocketRecv) goReceiveEvent() {
s.ingestError(sp)
}
case <-sockClosed: // socket is closed, leave now
s.resendNAKTicker.Stop()
s.resendACKTicker.Stop()
return
case <-s.resendNAKTimer:
if first, valid := s.recvLossList.FirstSequence(); valid {
s.sendNAK(first, 1)
} else {
// the trigger should not be activated if there is no loss list, but in case it happens, deactivate it
s.resendNAKTimer = make(chan time.Time)
s.resendNAKTicker.Stop()
}
case <-s.resendACKTimer:
case <-s.resendACKTimer: // handles both resending ACKs and NAKs
if s.recvAck2.IsLess(s.sentAck) {
s.sendACK(s.sentAck)
} else {
// the trigger should not be activated if there is no unacknowledged ACK list, but in case it happens, deactivate it
s.resendACKTimer = make(chan time.Time)
s.resendACKTicker.Stop()
}
if first, valid := s.recvLossList.FirstSequence(); valid {
s.sendNAK(first, 1)
}
}
}
@@ -126,12 +118,6 @@ func (s *udtSocketRecv) ingestAck2(p *packet.Ack2Packet, now time.Time) {
s.socket.applyRTT(uint(now.Sub(ackHistEntry.sendTime) / time.Microsecond))
if s.ackHistory.Count() == 0 {
// deactivate ACK timer, nothing expected for now
s.resendACKTimer = make(chan time.Time)
s.resendACKTicker.Stop()
}
//s.rto = 4 * s.rtt + s.rttVar
}
@@ -152,8 +138,6 @@ func (s *udtSocketRecv) ingestMsgDropReq(p *packet.MsgDropReqPacket, now time.Ti
}
if s.recvLossList.Count() == 0 {
s.lastSequence = s.nextSequenceExpect.Add(-1)
s.resendNAKTimer = make(chan time.Time)
s.resendNAKTicker.Stop()
}
// try to push any pending packets out, now that we have dropped any blocking packets
@@ -209,18 +193,10 @@ func (s *udtSocketRecv) ingestData(p *packet.DataPacket, now time.Time) {
s.sendNAK(s.nextSequenceExpect.Seq, uint32(seqDiff))
s.nextSequenceExpect = p.Seq.Add(1)
// set the timer for constantly resending NAKs for the lowest sequence ID
s.resendNAKTicker = *time.NewTicker(s.socket.Config.SynTime)
s.resendNAKTimer = s.resendNAKTicker.C
} else if seqDiff < 0 {
// If the sequence number is less than LRSN, remove it from the receiver's loss list.
if !s.recvLossList.Remove(p.Seq.Seq) {
return // already previously received packet -- ignore
} else if s.recvLossList.Count() == 0 {
// if loss list is empty, the NAK timer can be stopped
s.resendNAKTimer = make(chan time.Time)
s.resendNAKTicker.Stop()
}
} else {
s.nextSequenceExpect = p.Seq.Add(1)
@@ -506,8 +482,4 @@ func (s *udtSocketRecv) ackEvent() {
s.sendACK(ack)
s.unackPktCount = 0
// set the timer for constantly resending ACKs for the highest sequence ID
s.resendACKTicker = *time.NewTicker(s.socket.Config.SynTime)
s.resendACKTimer = s.resendACKTicker.C
}