Thread config tests not stable as it should

[duke8253]

This exception shows up sometimes.

Traceback (most recent call last):
  File "/usr/local/lib64/python3.6/site-packages/psutil/_common.py", line 340, in wrapper
    ret = self._cache[fun]
AttributeError: _cache

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib64/python3.6/site-packages/psutil/_pslinux.py", line 1517, in wrapper
    return fun(self, *args, **kwargs)
  File "/usr/local/lib64/python3.6/site-packages/psutil/_common.py", line 343, in wrapper
    return fun(self)
  File "/usr/local/lib64/python3.6/site-packages/psutil/_pslinux.py", line 1559, in _parse_stat_file
    with open_binary("%s/%s/stat" % (self._procfs_path, self.pid)) as f:
  File "/usr/local/lib64/python3.6/site-packages/psutil/_common.py", line 604, in open_binary
    return open(fname, "rb", **kwargs)
FileNotFoundError: [Errno 2] No such file or directory: '/proc/19527/stat'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib64/python3.6/site-packages/psutil/__init__.py", line 474, in _init
    self.create_time()
  File "/usr/local/lib64/python3.6/site-packages/psutil/__init__.py", line 824, in create_time
    self._create_time = self._proc.create_time()
  File "/usr/local/lib64/python3.6/site-packages/psutil/_pslinux.py", line 1517, in wrapper
    return fun(self, *args, **kwargs)
  File "/usr/local/lib64/python3.6/site-packages/psutil/_pslinux.py", line 1729, in create_time
    ctime = float(self._parse_stat_file()['create_time'])
  File "/usr/local/lib64/python3.6/site-packages/psutil/_pslinux.py", line 1524, in wrapper
    raise NoSuchProcess(self.pid, self._name)
psutil.NoSuchProcess: psutil.NoSuchProcess process no longer exists (pid=19527)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "check_threads.py", line 126, in <module>
    main()
  File "check_threads.py", line 122, in main
    exit(count_threads(args.ts_path, args.etnet_threads, args.accept_threads, args.task_threads, args.aio_threads))
  File "check_threads.py", line 31, in count_threads
    p = psutil.Process(pid)
  File "/usr/local/lib64/python3.6/site-packages/psutil/__init__.py", line 447, in __init__
    self._init(pid)
  File "/usr/local/lib64/python3.6/site-packages/psutil/__init__.py", line 487, in _init
    raise NoSuchProcess(pid, None, msg)
psutil.NoSuchProcess: psutil.NoSuchProcess no process found with pid 19527