Very Computer

In response to my previoud posted problem on rw_lock in multi-threading program,
I discovered that by using thr_yield after completion of one unit of work for
both Writer and Reader would prevent the seeminly deadlock situation.  
Can this approach solve th problem ?

However, I suspect that context switching on threads will be significant.
Is it true for this case?

Terence

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#include <stdio.h>
#include <thread.h>
#include <synch.h>
#include <errno.h>

rwlock_t RWLock;
long g;

void* writer();
void* reader();

void main()
{
        thread_t tid1,tid2;
        int thrResult1,thrResult2;
        int pri;

        g = 0;  

        rwlock_init ( &RWLock, USYNC_THREAD, 0 );

        thrResult1 = thr_create(NULL,0,writer,NULL,THR_NEW_LWP|THR_BOUND|THR_SUSPENDED,&tid1);
        thrResult2 = thr_create(NULL,0,reader,NULL,THR_NEW_LWP|THR_BOUND|THR_SUSPENDED,&tid2);

        thr_continue(tid1);
        thr_continue(tid2);

        for (;;);

Quote:}

void* writer()
{

        int i,k,cnt=0;

        for  ( ;; ) {
            for ( ; rw_trywrlock( &RWLock ) != 0; ) {};                                    
            g++;
            if  ( cnt++ > 1000000 ) {
                cnt = 0;
            };
            rw_unlock ( &RWLock );
            thr_yield();
        };

Quote:}

void* reader()
{
        int cnt;

        for ( ;; ) {
            rw_rdlock ( &RWLock );
            if  ( cnt++ > 1000000 ) {
                cnt = 0;
                printf("Reader 1 : %d  \n",g);
            };
            rw_unlock ( &RWLock );
            thr_yield();
        };

Quote:}

Terence,

  Did you see my reply?  (I'm not sure it showed up here.)  Basically I see
no particular problems (a few nits) with your program, and it works as
expected for me.

-Bil
--
Det ?r den som g?r vilse, som finner de nya v?garna

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