$2$nd Try at Readers & Writers

monitor readerWriter$\_21$

int numberOfReadera $0$; boolean buay FALSE;

condition oktoRead, okToWrite;

public: atartRead$()($

$1\mathrm{.}2$ okToRead.wait$()$:

$13$ numberOfReaders$++$; $14$ oktoRead.signal$()$;

finishRead$()($

LS numberOfReaders$-$

$16$ if $($numberOfReaders $0)$

$17$ okToWrite.signal$()$;

startWritel$)$

if $($buay $!!($okToWrite$.$queue$()$; if $($numberOfReaders $1-0)$

$11$ busy$)$

L$9$ okToWrite.wait$()$;

$210$ busy TRUE:

finishWrite$()$

L$11$ buay FALSE,

$112$ if $($oktoRead$,$ queue $(1)$ L$13$ okToRead.signal $(1$

else

L$14$ okToWrite.signal$()$

$8.$ The above prograns is one solution to the Reader Writer problem. Suppose that we have the following case as one example execution of the above program:

RI: Reader process $1.$ R$2$: Reader process $2,$ W$1$: Writer process $1.$

R$1$ arrvies and invokes startRead$()$

R$2$ arrives and invokes startRead$()$

W$1$ arrives and invokes startWrite$()$

R$1$ finishes and Invokes finishRead$()$

R$2$ finishes and Invokes finishRead$()$

$0$ to

Questions: $(9$ points$)$

Trace the program execution $($using the format presented in the class$),$ You need indicate when and why a process is blocked.