Example 63 Detecting multi-threaded programming issues

#include<PTHREAD.H> #include <STDIO.H> int a; pthread_mutex_t Mutex;

void perform_operation(pthread_mutex_t* mutex1, int increment, int* global)

{

if (increment > 10)

{

int status = pthread_mutex_lock(mutex1);

}

*global = *global + increment;

int status = pthread_mutex_unlock(&Mutex);

}

int main(void)

{

int i; scanf("%d", &i);

perform_operation(&Mutex, i, &a); printf("%d is value\n", a);

}

Running cadvise generates the following error:

"1.c", line 12: warning #20223-D: Trying to unlock a lock held conditionally

With the +wlock option, warnings are generated for potential errors in using lock/unlock calls from pthread library. This is based on cross-module analysis performed by the compiler, which is much more powerful compared to simple scanning and parsing tools. The +wlock option implicitly enables a limited form of cross-module analysis even if -ipoor +O4 options are not specified.

This may lead to a significant increase in the compile time compared to a build without the +wlock option.

The +wlock option requires cross module analysis. Hence, you need to specify the location of the PDB using the -pdboption.

8.7 Detecting potential performance improvement opportunities

The +wperfadvice[=1234] option generates Performance Advisory diagnostics. The performance advisory diagnostics are classified within specific levels. You can specify the level of performance advisory diagnostics to be displayed. The level '1', emits the most important diagnostics and level '4' emits all diagnostics. The default level is '2'.

54 Categories of diagnostics with examples