Remove callstack sampler util which is not used in any code.

PiperOrigin-RevId: 353526459

official/utils/misc/callstack_sampler.py

-"""A simple Python callstack sampler."""
-
-import contextlib
-import datetime
-import signal
-import traceback
-
-
-class CallstackSampler(object):
-  """A simple signal-based Python callstack sampler.
-  """
-
-  def __init__(self, interval=None):
-    self.stacks = []
-    self.interval = 0.001 if interval is None else interval
-
-  def _sample(self, signum, frame):
-    """Samples the current stack."""
-    del signum
-    stack = traceback.extract_stack(frame)
-    formatted_stack = []
-    formatted_stack.append(datetime.datetime.utcnow())
-    for filename, lineno, function_name, text in stack:
-      formatted_frame = '{}:{}({})({})'.format(filename, lineno, function_name,
-                                               text)
-      formatted_stack.append(formatted_frame)
-    self.stacks.append(formatted_stack)
-    signal.setitimer(signal.ITIMER_VIRTUAL, self.interval, 0)
-
-  @contextlib.contextmanager
-  def profile(self):
-    signal.signal(signal.SIGVTALRM, self._sample)
-    signal.setitimer(signal.ITIMER_VIRTUAL, self.interval, 0)
-    try:
-      yield
-    finally:
-      signal.setitimer(signal.ITIMER_VIRTUAL, 0)
-
-  def save(self, fname):
-    with open(fname, 'w') as f:
-      for s in self.stacks:
-        for l in s:
-          f.write('%s\n' % l)
-        f.write('\n')
-
-
-@contextlib.contextmanager
-def callstack_sampling(filename, interval=None):
-  """Periodically samples the Python callstack.
-
-  Args:
-    filename: the filename
-    interval: the sampling interval, in seconds. Defaults to 0.001.
-
-  Yields:
-   nothing
-  """
-  sampler = CallstackSampler(interval=interval)
-  with sampler.profile():
-    yield
-  sampler.save(filename)
-