Process Synchronization

1
Process Synchronization

• ?. ??????? ??????????

2
?????????????????????

• ???????????????????????? 1 ???
• ??????????????? (Mutual Exclusion)
• ???????? (Critical Section)
• Producer-Consumer problem
• Semaphore
• Dining Philosophers Problem

3
?????

• ?????????????????????????? ????.?. ????????
  ?????????????? ?????????????????????
• ??? ?.?. ????????????????
• 1. PCB ???????
• 2. ????????????????????????
• 3. ?????????????????????????????
• 4. Context Switch ???????
• 5. Thread ??????????????

4
??????? ?????????????? CPU
Process
CPU

• ????
• DOS

5
?????????????????????
Process
Process
Process
CPU

• ??? PCB ???? Context Switch
• ?????????????? Deadlock, Loss of Data
  Integrity, etc.

6
???????? Loss of Data Integrity

• ?????????????? ?????????????????????
• ????????????????????????????????????? ????
  ??????, ????, ?????????, Address Space ???????
• ?????????? OS ??? ?????? ???????????????????????
  ?????

?????. ???????????? 5 ?? ?????????????????????????
????????????????
7
????? Producer-Consumer

• ??????????????????????????????????????????????
• ???? ????????????? WinAmp, ???????????????? Web
  Browser
• ???????????? ???? Buffer ?????????????????????
• ??????? Process ???? 2 ??? ?????? Producer ???
  Consumer ?????????????????????????? Buffer
  ?????????????????????????? Buffer

Producer
Consumer

Buffer
Data
8
??????????????????????? ?

• ??????? ?.?. ?????? 5 ???? ???????????????????????
  ?????????????????? Producer-Consumer
  ????????????????????
• ..
• ?????
• ???????????????????????
• ??? Producer ?????????/?????????
• ??? Consumer ?????????/?????????
• ??? Buffer ??????????
• ??? Buffer ??????????

9
????????????

• ??????? ?.?. ?????? 5 ???? ???????????????????????
  ????????????????? Producer-Consumer
  ????????????????????
• .....
• ?????????????????
• ????????????????????????? (Synchronize)
• ??????????????????????????????????????????????
• Producer ???????????????
• Consumer ??????????????

10
???????????

• ???????? Buffer ???? ?????? ????????? n1
• Producer ????????????????????????? in
• Consumer ???????????????????????? out

0
1
n
2
out
in
11
????????????????????? ?

• LAB
• ??? ??. ?????????? ??????????????????????????????
  ????????????????? O.S.2 ??????????????? LAB.
• ????????????? LAB os2-1
• ??????? 20 ????
• ????????????? ???????????

12
LAB os2-1

• ????????????
• 1. ???????? ??. ???????????????????????
• 2. ?????????????????????????????????????? OS ???
• ?????
• ????????? ?????????????? ?????????????????????
• ????????????????? ????? (index)

0
1
n
2
13
????????????????? C
(?????)
14
???
???????????????????????? ?
????????? Process ??? Producer ??? Consumer
15
???????????????????

• ???????????????????? 2 ?????? ??????????
  ???????????????????????????????
  ??????????????????????????????????????????????????
  ?
• ??????????? Database ???? ???? ????????????????
• ???????????????????
• Thread
• ??? 2 Threads ???????????????????
• Java ????????????????? Thread

16
??????????? Thread

• Thread ??? ?????????????? (Light weight process)
• Thread ????? Memory ?? Address Space
  ??????????????
• Thread ????????????????????? (Multi-threading)

Process
Thread
CPU
17
???????????? Java ?????? Thread
18
???????? ??????????
??????? Producer
19
Consumer
20
??????????