1. persimmon
load balancer
Solution Engineering
FUKUTOMI Yutaka

2. if no balancer

3. with balancer
LB

4. thread
LB
listener
server thread
server thread
server thread

5. server thread
loop{
read from client;
write to server;
read from server;
write to client;
}

6. selector
LB
selector
client server

7. selector
loop{
select;
if(accept)
connect to server;
if(on read)
write to other;
}

8. session
session data

9. fool balancer
LB
session data
NO session data !!
session error !!

10. wise balancer
LB session data
client server
A X
A
X
Y

11. session with wise balancer
LB
session data
for A
session data
for B
A
B
X
Y
client server
A X
B Y

12. reliability
LB

13. when LB down
LB

14. active/standby
LB
LB
active
standby

15. normal
LB
LB
active
standby
a
b
(x)
connect to “x”
Hey! I’m alive!!
“active” is live.
I stay as “standby”

16. when active LB is down
LB
LB
active
standby
a
b
(x)
connect to “x”
no “active”
is alive?

17. failover
LB
LB
active
a
b
(x)
connect to “x”
I become
“active”.
Hey! I’m alive!!

18. 終劇 (fin)