Calling dlopen then dlclose causes an increase in the amount of memory used by the program. If I create a loop that calls dlopen / dlclose repeatedly on the same dynamic library, memory usage increases continuously. Is this a bug, or am I using dlopen / dlclose incorrectly?
I can reproduce this by modifying the sample code in the Apple Developer docs Creating Dynamic Libraries. If I modify Runtime.c, changing the line void *lib_handle = dlopen(lib_name, RTLD_NOW); to add the infinite loop, as below:
void *lib_handle = dlopen(lib_name, RTLD_NOW);
for (int ii = 0; ; ++ii) {
printf("loop %i\n", ii);
int close_err = dlclose(lib_handle);
printf("close error: %i\n", close_err);
printf("dlopen(%s, RTLD_NOW)\n", lib_name);
lib_handle = dlopen(lib_name, RTLD_NOW);
}
then opening and closing the dynamic library will succeed, but memory usage (as reported by top) will rapidly increase.
I'm running on x86_64 macOS 13.6.6. Full code for the modified Runtime.c is attached, the rest of the code is available in the Apple Developer docs.
Any suggestions?
Many thanks,
Chris
Runtime.c
