SonarCloud complains this is a dodgy access:

bool JfrCPUSamplerThread::create_timer_for_thread(JavaThread* thread, timer_t& timerid) {
  struct sigevent sev;
  sev.sigev_notify = SIGEV_THREAD_ID;
  sev.sigev_signo = SIG;
  sev.sigev_value.sival_ptr = nullptr;
  ((int*)&sev.sigev_notify)[1] = thread->osthread()->thread_id(); // <--- here

I suspect the intent is to reach for platform-specific _tid field there. The current expression seems to hit the right spot:

typedef struct sigevent {
    __sigval_t sigev_value;
    int sigev_signo;
    int sigev_notify;
    union {
        int _pad[__SIGEV_PAD_SIZE];
        __pid_t _tid;
       struct {
              void (*_function) (__sigval_t); /* Function to start. */
              pthread_attr_t *_attribute; /* Thread attributes. */
        } _sigev_thread;
    } _sigev_un;
} sigevent_t;

...but I do not think it is 100% portable. Maybe it is possible to somehow access `sev._sigev_un._tid` directly without breaking too many builds.