進程管理-基本概念

進程同進程同步的基本概 2.3進程同

VARtop:integer=-1stack:array[0..n-1]ofProgramAwhile(TRUEtop:=(top+1)mod stack[top]:=x endProgramBwhile(TRUEtop:=(top+1)mod stack[top]:=y endwhile 2.3進程同

VARtop:integer=-1ProgramAwhileProgramAwhile(TRUEtop:=(top+1)modstack[top]:=xend 如何實現(xiàn)臨界資源的互

ProgramBwhile(TRUEtop:=(top+1)modstack[top]:=yendwhile201arend2.3進程同 臨界資 互臨界 互

VARtop:integer=-1stack:array[0..n-1]ofitem;ProgramA:while(TRUEtoptop:=(top+1)modn;stack[top]:=x;endwhileProgramB:while(TRUEtoptop:=(top+1)modn;stack[top]:=y;

end201arend2.3進程同criticalsectioncriticalsectionremaindersectionuntil

entrycriticalsection;exitsection;remaindersection;untilfalse空閑讓進：當無進程處于臨界區(qū)忙則等待：當已有進程進入臨界有限等待：對要 臨界資源進程，保證能在有限時間內(nèi)進入臨界讓權(quán)等待：當進程不能進入臨界區(qū)時，應釋放處理機 2.3進程同

VARfree:boolean:=false實現(xiàn)進程同步的早期軟件解法1資源空閑標志:free=false:Free=true:

Programwhile(while(free)free:=truefree:=falsefree:=falseuntilProgramwhile(while(free)free:=truefree:=falsefree:=false

remaindersectionuntilfalse82.3進程同

VARturn:integer:=12.3.2實現(xiàn)進程同步的早期

Programwhile(while(turn=2)turn:=2turn:=2remaindersectionuntil嚴格限制資 順

Programwhile(while(turn=1)turn:=1turn:=1

remaindersectionuntilfalse92.3進程同

VARpturn,qturn:boolean:=false,false2.3.2實現(xiàn)進程同步的早期方Programpturn:=truepturn:=truewhile(qturn)

criticalsection;remaindersection;pturn:=falsepturn:=falseProgramqturnqturn:=truewhile(pturn)criticalsectionqturnqturn:=falseremaindersection;untilfalse

12.3進程同2.3.2實現(xiàn)進程同步的早期方#defineFALSE#define

Programenter_region(0enter_region(0criticalsection intint

進程的個 數(shù)組，初始值均為

remaindersectionuntilvoidenter_regionintprocessprocess0或{int //另外一個進程的進程other=1- interested[process]=TRUE表明本進程turn= 設置標志while(turn==process&&interested[other]==}voidleave_region(int{interested[process]= //本進程已離開

Programenter_region(1);criticalsection;remaindersection;untilfalseVARlock:boolean:=VARlock:boolean:=falseProgramcriticalsectionremaindersectionuntilfalseProgramcriticalsection;remaindersection;untilenter_region(lock2.3.2實現(xiàn)進程同步的早期方//交換鎖lock//交換鎖lock和key的functionSWAP(lock,key){vartmp:boolean:=lock;lock:=key;key:=tmp}functionfunctionenter_region(varlockbooleanVarkey:boolean;//局部變量key:=functionleave_region(varlock:booleanlock:=false;進程同實現(xiàn)進程同步的早期方 信號量機制的提出荷蘭計算機科學家EdsgerWybeDijkstra; 第一個Algol60編譯器的設計者 VARS:integer:=1VARS:integer:=1;ProgramP1:criticalsectionremaindersection;untilfalseProgramcriticalsectionremaindersectionuntil信號量機整數(shù)信號量S; P/VfunctionfunctionWait(varS:integerwhile(S<=0)dono_op();S:=S-1;functionSignal(varS:integer)S:=VARS:semaphore:=1;ProgramP1:VARS:semaphore:=1;ProgramP1:criticalsection;remaindersection;untilfalseProgramcriticalsection;remaindersection;untilwait(S兩個原子操作 P/Vtypesemaphore=value:integerL:listofprocess

//阻塞進程隊functionwait(varS：Semaphore)S.value:=S.value-if(S.value<0)thenblock(S.L);functionsignal(varS：SemaphoreS.value:=if(S.value<=0)thenwakeup(S.L);2.3進程同(2)資源，因此描述為S.value:=S.value-1；當S.value＜0時，表源，故S.value:=s.value+1操作表示資源數(shù)目加1。若加1后仍S.value:S.value>=0:資源數(shù)量；S.value<0: |S.value|合肥工業(yè)大學操作系統(tǒng)課程組 2.3進程同信號量的應例1：2

VARtop:integer=-1stack:array[0..n-1]ofmutex:semaphore:=1ProcessProcessP1while(TRUEtop:=(top+1)modstack[top]:=xendsignal(mutex)wait(mutex)ProcessProcessP2while(TRUEtop:=(top+1)modn;stack[top]:=y;endwhilesignal(mutex)wait(mutex)

2.3進程同(1)河河河河 ProcessN2SProcessN2Sgoacrossthebridgeuntilsignal(mutex)wait(mutex)ProcessS2Ngoacrossthebridge;untilfalsesignal(mutex)wait(mutex)VARmutex:semaphore=1ProcessN2Sgoacrossthebridge;untilfalseProcessS2Ngoacrossthebridge 2.3進程同(2)B VARS1,S2:VARS1,S2:semaphore=1,0ProcessPIreadxfromI/OB:=xuntilProcessPOy:=Bprint(y);untilfalsesignal(S1)wait(S2)signal(S2)wait(S1)ProcessPOy:=Bprint(y)untilProcessPIreadxfromI/O;B:=x;until組組 進程同(2)B3：IEBI負責產(chǎn)生隨機數(shù)B中，當B中數(shù)據(jù)為奇數(shù)時由O負責打印，當B中數(shù)B ProcessProcessPEy:=Bprint(y);untilfalseProcessPOz:=Bprint(z);untilfalseProcessPIgeneratexB:=xuntilvarS,SO,SE:semaphoreProcessPEy:=B;signal(S);print(y);ProcessPOz:=Bsignal(S);print(z);untilProcessPIgeneratexB:=xif(xisodd)signal(SO); signal(SE)until組組 經(jīng)典進程同步問生產(chǎn)者-消費者問循環(huán)緩沖

出隊操 VARempty,full:semaphore:=n,0;in,out:integer:=0,0;Buffer:array[0..n-1]ofitemproduceaniteminnextp;wait(empty);Buffer(in):=nextp;in:=(in+1)modn;signal(full)untilwait(full)nextc=out:=(out+1)modn課程組課程組

signal(empty)consumetheitemnextc;untilflasein,out:integerin,out:integer:=0,0Buffer:array[0..n-1]ofitem produceaniteminnextpBuffer(in):=nextp;in:=(in+1)modn;untilnextc=out:=(out+1)modnconsumetheitemnextc;untilflase

VARmutex,VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0Buffer:array[0..n-1]ofitem;produceaniteminnextp;wait(empty);wait(mutex);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilwait(full);wait(mutex);nextc=out:=(out+1)modnsignal(mutex);signal(empty)consumetheitemnextc;untilflase (2)

合肥工業(yè)大學操作

VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(empty)wait(mutex);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(full)wait(mutex);nextc=Buffer(out);out:=(out+1)modnsignal(mutex);signal(empty)consumetheitemnextcuntilflase(2)

VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(empty)wait(mutex);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(full)wait(mutex)nextc=out:=(out+1)modnsignal(mutex);signal(empty)consumetheitemnextcuntil合肥工業(yè)大學操作

(2)

VARmutex,empty,full:semaphore:=1,n,0;in,out:integer:=0,0;Buffer:array[0..n-1]ofitemproduceaniteminnextp;wait(empty);Buffer(in):=nextp;in:=(in+1)modn;

signal(full)untilwait(full)nextc=out:=(out+1)modn合肥工業(yè)大學操作系統(tǒng)

signal(empty);consumetheitemnextc;程組 程組 (2)

同例VARempty,full:VARempty,full:semaphore:=1,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextp;wait(empty);Buffer(in):=nextp;in:=(in+1)modn;signal(full);untilwait(full)nextc=out:=(out+1)modn;signal(empty);consumetheitemnextc;until(2)

VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(empty)wait(mutex);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(full)wait(mutex);nextc=Buffer(out);out:=(out+1)modnsignal(mutex);signal(empty)consumetheitemnextc系統(tǒng)課程組 系統(tǒng)課程組 合肥工業(yè)大學操

(2)

VARmutexC,mutexP,empty,full:semaphore:=1,1,n,0;in,out:integer:=0,0;Buffer:array[0..n-1]ofitemproduceaniteminnextp;wait(empty);wait(mutexP);Buffer(in):=nextp;in:=(in+1)modn;signal(mutexP);signal(full);untilwait(full)wait(mutexC);nextc=Buffer(out);out:=(out+1)modnsignal(mutexC);signal(empty);consumetheitemnextc;操作系統(tǒng)課程組 操作系統(tǒng)課程組 合肥工業(yè)大

(2)

VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(empty)wait(mutex);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(full)wait(mutex);nextc=Buffer(out);out:=(out+1)modnsignal(mutex);signal(empty)consumetheitemnextc作系統(tǒng)課程組 作系統(tǒng)課程組 合肥工業(yè)大學

(2)

合肥工業(yè)大學

VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(mutex);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(full)wait(mutex);nextc=Buffer(out);out:=(out+1)modnsignal(mutex)consumetheitemnextc;untilflase作系統(tǒng)課程組作系統(tǒng)課程組 (2)

合肥工業(yè)大學

VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(mutex)wait(empty);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(full)wait(mutex);nextc=Buffer(out);out:=(out+1)modnsignal(mutex);signal(empty)consumetheitemnextcuntil作系統(tǒng)課程組作系統(tǒng)課程組 (2)

合肥工業(yè)大學

VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(empty)wait(mutex);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(mutex)wait(full)nextc=out:=(out+1)modnsignal(mutex)signal(empty);consumetheitemnextc;until作系統(tǒng)課程組作系統(tǒng)課程組 (2)

VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(mutex)wait(empty);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(mutex)wait(full)nextc=out:=(out+1)modnsignal(mutex);signal(empty)consumetheitemnextcuntil合肥工業(yè)大學4操作系統(tǒng)end組(2)VARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(empty);wait(mutex)Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(full)wait(mutex);nextc=Buffer(out);out:=(out+1)modnsignal(empty);signal(mutex)consumetheitemnextcuntil合肥工業(yè)大學4操作系統(tǒng)end組(2)

VARVARmutex,empty,full:semaphore:=1,n,0in,out:integer:=0,0;Buffer:array[0..n-1]ofitem;produceaniteminnextpwait(empty)wait(mutex);Buffer(in):=nextp;in:=(in+1)modn;signal(mutex);signal(full);untilflasewait(full)wait(mutex);nextc=Buffer(out);out:=(out+1)modnsignal(mutex);signal(empty)consumetheitemnextcuntil 合肥工業(yè)大學2.4經(jīng)典進程同步問讀者-寫者問

讀寫讀寫 VARVARwmutex:semaphore:=1wait(wmutex);performreadoperation;signal(wmutex);untilflasewait(wmutex);performwriteoperation;signal(wmutex);untilflase VARVARwmutex:semaphore:=1readcount:integer:=0if(readcount=0)wait(wmutex);readcount:=readcount+1;performreadoperation;readcount:=readcount-1if(readcount=0)signal(wmutex);untilflasewait(wmutex);performwriteoperation;signal(wmutex);until

VARVARwmutex:semaphore:=1;readcount:integer:=0;if(readcount=0)wait(wmutex);readcount:=readcount+1;performreadoperation;readcount:=readcount-1if(readcount=0)signal(wmutex);untilflasewait(wmutex);performwriteoperation;signal(wmutex);untilVARrmutex,wmutex:semaphore:=1,1;readcount:integer:=0;wait(rmutex)VARrmutex,wmutex:semaphore:=1,1;readcount:integer:=0;wait(rmutex)if(readcount=0)wait(wmutex);readcount:=readcount+1;signal(rmutex);performreadoperationwait(rmutex)readcount:=readcount-1if(readcount=0)signal(wmutex)signal(rmutex)untilwait(wmutex);performwriteoperation;signal(wmutex);untilflase VARrmutex,wmutex:VARrmutex,wmutex:semaphore:=1,1readcount:integer:=0;wait(rmutex)if(readcount=0)wait(wmutex);readcount:=readcount+1;signal(rmutex);performreadoperationwait(rmutex)readcount:=readcount-1if(readcount=0)signal(wmutex)signal(rmutex)untilwait(wmutex);performwriteoperation;signal(wmutex);untilflase 2.4經(jīng)典進程同步問哲學家進餐問 哲學家進程：互斥（筷子 VARVARchopsticks:array[0..4]ofsemaphore:=1,1,1,1,1wait(chopsticks[i])wait(chopsticks[(i+1)mod5]eatsignal(chopsticks[i])signal(chopsticks[(i+1)mod5]untilflase 0 2

VARVARchopsticks:array[0..4]ofsemaphore:=1,1,1,1,1philosopher0-wait(chopsticks[i])wait(chopsticks[(i+1)mod5]);eat;signal(chopsticks[i])signal(chopsticks[(i+1)mod5]untilflasewait(chopsticks[(i+1)mod5]wait(chopsticks[i]);eat;signal(chopsticks[i])signal(chopsticks[(i+1)mod5]untilflase4 0 2 經(jīng)典進程同步問理發(fā)師問題(課后思考題(1) 2.4經(jīng)典進程同步問信號量集機 2.4.5信號量集機typesemaphore=value:integerL:listofprocess;

//阻塞進程隊functionSwait(varS1,S2,..,Sn：Semaphoreif(S1>=1and…andSn>=1)fori:=1tondoSi:=Si-1PlacetheprocessinthequeueassociatedwiththefirstSifoundwithSi<1,gotothebeginningoffunctionSsignal(varS1,S2,..,Sn：Semaphorefo