Pthread error?

Fri Jul 29 17:10:00 GMT 2011

Don't know why all the white space in the code turned intro "?".
Hopefully this is better:
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define checkResults(string, val) { \
 if (val) { \
 printf("Failed with %d at %s", val, string); \
 exit(1); \
 } \
}
#define NUMTHREADS 5
pthread_once_t oneTimeInit = PTHREAD_ONCE_INIT;
int initialized = 0;
int resource = 0;
void initFunction(void)
{
 printf("Thread %.8x %.8x: INITIALIZE RESOURCE\n");
 initialized = 1;
 resource = 42;
 printf("Thread %.8x %.8x: initialized is>>> %d\n",
	 pthread_self(), initialized);
}
void *theThread(void *parm)
{
 int rc;
 printf("Thread %.8x %.8x: Entered\n", pthread_self());
 //if (!initialized) {
 rc = pthread_once(&oneTimeInit, initFunction);
 checkResults("pthread_once()\n", rc);
 //}
 printf("Thread %.8x %.8x: The resource is %d\n",
	 pthread_self(), resource);
 return NULL;
}
int main(int argc, char **argv)
{
 pthread_t thread[NUMTHREADS];
 int rc=0;
 int i;
 printf("Enter Testcase - %s\n", argv[0]);
 printf("Create/start threads\n");
 for (i=0; i <NUMTHREADS; ++i) {
 rc = pthread_create(&thread[i], NULL, theThread, NULL);
 checkResults("pthread_create()\n", rc);
 }
 printf("Wait for the threads to complete, and release their resources\n");
 for (i=0; i <NUMTHREADS; ++i) {
 rc = pthread_join(thread[i], NULL);
 checkResults("pthread_join()\n", rc);
 }
 printf("Main completed\n");
 return 0;
}
On Fri, Jul 29, 2011 at 12:59 PM, Jan Chludzinski
<jan.chludzinski@gmail.com> wrote:
>> The code below appears to have incorrect behavior.  The output is:
>> $ ./a.exe
> Enter Testcase - ./a
> Create/start threads
> Thread 009e0290 00000000: Entered
> Thread 009f0320 00000000: Entered
> Thread 009f03a8 00000000: Entered
> Thread 18dbce64 00000000: INITIALIZE RESOURCE
> Wait for the threads to complete, and release their resources
> Thread 009f0430 00000000: Entered
> Thread 00a104f8 00000000: Entered
> Thread 009e0290 00000001: resource is>>> 0
> Thread 009e0290 0000002a: The resource is 0
> Thread 009f0320 0000002a: The resource is 0
> Thread 009f03a8 0000002a: The resource is 0
> Thread 009f0430 0000002a: The resource is 0
> Thread 00a104f8 0000002a: The resource is 0
> Main completed
>> If I understand pthread_once(...) correctly, the output should be:
>> Thread ... ...: The resource is 42
>> for all threads.  The really strange thing is the printf(...) in
> initFunction().  This should print "resource is>>> 42" but I get:
> "resource is>>> 0".
>> What's up?
>> I'm using Cygwin 1.7 on Windows 7 with gcc (GCC) 4.3.4 20090804 (release) 1.
>> ---John
>>> ////////////////////////////////////////////////////////////////////////////////////////////////////////
>> #include <pthread.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
>> #define checkResults(string, val) {             \
>  if (val) {                                     \
>    printf("Failed with %d at %s", val, string); \
>    exit(1);                                     \
>  }                                              \
> }
>> #define                 NUMTHREADS   5
> pthread_once_t          oneTimeInit = PTHREAD_ONCE_INIT;
> int                     initialized = 0;
> int                     resource    = 0;
>> void initFunction(void)
> {
>    printf("Thread %.8x %.8x: INITIALIZE RESOURCE\n");
>    initialized = 1;
>    resource = 42;
>    printf("Thread %.8x %.8x: resource is>>> %d\n",
>      pthread_self(), resource);
> }
>> void *theThread(void *parm)
> {
>   int   rc;
>   printf("Thread %.8x %.8x: Entered\n", pthread_self());
>   //if (!initialized) {
>     rc = pthread_once(&oneTimeInit, initFunction);
>     checkResults("pthread_once()\n", rc);
>     //}
>   printf("Thread %.8x %.8x: The resource is %d\n",
>      pthread_self(), resource);
>   return NULL;
> }
>> int main(int argc, char **argv)
> {
>   pthread_t             thread[NUMTHREADS];
>   int                   rc=0;
>   int                   i;
>>   printf("Enter Testcase - %s\n", argv[0]);
>>   printf("Create/start threads\n");
>   for (i=0; i <NUMTHREADS; ++i) {
>     rc = pthread_create(&thread[i], NULL, theThread, NULL);
>     checkResults("pthread_create()\n", rc);
>   }
>>   printf("Wait for the threads to complete, and release their resources\n");
>   for (i=0; i <NUMTHREADS; ++i) {
>     rc = pthread_join(thread[i], NULL);
>     checkResults("pthread_join()\n", rc);
>   }
>>   printf("Main completed\n");
>   return 0;
> }

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