RFR: 8368124: Show useful thread names in ASAN reports [v2]

[Thomas Stuefe]

On Mon, 22 Sep 2025 06:15:20 GMT, David Holmes <dholmes at openjdk.org> wrote:

> I see now in JBS that you say you don't know why what we have doesn't work for ASAN, but I think we need to determine that.

Hmm, I see in glibc that they also do prctl;


int
__pthread_setname_np (pthread_t th, const char *name)
{
  const struct pthread *pd = (const struct pthread *) th;

  /* Unfortunately the kernel headers do not export the TASK_COMM_LEN
     macro.  So we have to define it here.  */
#define TASK_COMM_LEN 16
  size_t name_len = strlen (name);
  if (name_len >= TASK_COMM_LEN)
    return ERANGE;

  if (pd == THREAD_SELF)
    return __prctl (PR_SET_NAME, name) ? errno : 0;

#define FMT "/proc/self/task/%u/comm"
  char fname[sizeof (FMT) + 8];
  sprintf (fname, FMT, (unsigned int) pd->tid);

  int fd = __open64_nocancel (fname, O_RDWR);
  if (fd == -1)
    return errno;

  int res = 0;
  ssize_t n = TEMP_FAILURE_RETRY (__write_nocancel (fd, name, name_len));
  if (n < 0)
    res = errno;
  else if (n != name_len)
    res = EIO;

  __close_nocancel_nostatus (fd);

  return res;
}


No idea why this doesn't work on my machines. I run Fedora 42 and Debian 12. Will look a bit deeper.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27395#discussion_r2371223381