Mail Archives: cygwin/2011/07/29/13:10:17
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| Date: | Fri, 29 Jul 2011 13:09:47 -0400
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| Message-ID: | <CADqjQ-J34-mayfS-g-RneUe9QbzMauHbZauG5Cq2iOjxr2QW4A@mail.gmail.com>
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| Subject: | Re: Pthread error?
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| From: | Jan Chludzinski <jan DOT chludzinski AT gmail DOT com>
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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 DOT chludzinski AT gmail DOT 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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