Get number of active threads spawned by current process on MacOS-CodePudding

I've been searching for the last 3 hours online and through system headers, but can not find a mechanism available to me in C/C for what I'm trying to do on MacOS.

I'm looking to find a way to retrieve for the currently running process the total number of active/alive threads. I acknowledge that this would be trivial if I were counting threads that I myself spawn, but this is not the case. The code base I'm working on uses several threading libraries, and I require this basic information for debugging purposes.

On linux I can just acces /proc/self/stat/ where the 20th element is the total number of alive threads, but this is not available on MacOS. If it helps, this has to work on MacOS 12.0

Does anyone have any ideas?

CodePudding user response：

From a bit of googling around, it seems to me like you should be able to obtain this information using task_threads(), after getting the right mach port from task_for_pid():

int pid = 123; // PID you want to inspect
mach_port_t me = mach_task_self();
mach_port_t task;
kern_return_t res;
thread_array_t threads;
mach_msg_type_number_t n_threads;

res = task_for_pid(me, pid, &task);
if (res != KERN_SUCCESS) {
    // Handle error...
}

res = task_threads(task, &threads, &n_threads);
if (res != KERN_SUCCESS) {
    // Handle error...
}

// You now have `n_threads` as well as the `threads` array
// You can use these to extract info about each thread

res = vm_deallocate(me, (vm_address_t)threads, n_threads * sizeof(*threads));
if (res != KERN_SUCCESS) {
    // Handle error...
}

Note however that the usage of task_for_pid() might be restricted. I don't know much about how entitlements work on macOS, but you can check these other posts: