php extension with pthreads

hi i am new to php and am building my first php extension. i have a code in cpp that uses pthreads for carrying out the job. i tried to convert this into a php extension but was unable to do so despite a number of tries. i am able to compile the extension that i build but am unable to load it. the error that i get is :: PHP Warning: Unknown(): Unable to load dynamic library '/home/y/lib/php/20020429/perfext.so' - /home/y/lib/php/20020429/perfext.so: Undefined symbol "pthread_exit" in Unknown on line 0 i have used the line PHP_ADD_LIBRARY_WITH PATH to include pthread library and also used -pthread in the cppflags. do i need to do anything else for creating such an extension.