class_docstr: Parallel processing base class.
  
  Base class for parallel processing engines.
  
  Parameters
  ----------
  backend: str, optional
      Type of backend. One of ``'threading'``, ``'multiprocessing'``,
      ``'sequential'``.
  
  n_jobs : int, optional
      Degree of concurrency.
  
  verbose: bool, int, optional
      Level of verbosity of the
      :class:`~mlens.externals.joblib.parallel.Parallel` instance.
class_docstr_tok: ["Parallel","processing","base","class",".","Base","class","for","parallel","processing","engines",".","Parameters","--","--","--","--","--","backend",":","str",",","optional","Type","of","backend",".","One","of","``","'threading","'","``",",","``","'multiprocessing","'","``",",","``","'sequential","'","``",".","n_jobs",":","int",",","optional","Degree","of","concurrency",".","verbose",":","bool",",","int",",","optional","Level","of","verbosity","of","the",":","class",":","`","~mlens.externals.joblib.parallel.Parallel","`","instance","."]
docstr: Destroy cache and reset instance job parameters.
docstr_tok: ["Destroy","cache","and","reset","instance","job","parameters","."]
code: def clear(self):
      """Destroy cache and reset instance job parameters."""
      # Detach Job instance
      job = self.job
      self.job = None
      self.__initialized__ = 0
  
      if job:
          path = job.dir
          path_handle = job.tmp
  
          # Release shared memory references
          del job
          gc.collect()
  
          # Destroy cache
          try:
              # If the cache has been persisted to disk, remove it
              if isinstance(path, str):
                  path_handle.cleanup()
          except (AttributeError, OSError):
              # Python 2 has no handler, can also fail on windows
              # Use explicit shutil process, or fall back on subprocess
              try:
                  shutil.rmtree(path)
              except OSError:
                  # Can fail on windows, need to use the shell
                  try:
                      subprocess.Popen(
                          "rmdir /S /Q %s" % path,
                          shell=True,
                          stdout=subprocess.PIPE,
                          stderr=subprocess.PIPE,
                      ).kill()
                  except OSError:
                      warnings.warn(
                          "Failed to delete cache at %s."
                          "If created with default settings, will be "
                          "removed on reboot. For immediate "
                          "removal, manual removal is required." % path,
                          ParallelProcessingWarning,
                      )
          finally:
              del path, path_handle
              gc.collect()
              if gc.garbage:
                  warnings.warn(
                      "Clearing cache failed, uncollected:\n%r"
                      % gc.garbage,
                      ParallelProcessingWarning,
                  )
  
imports: from __future__ import with_statement, division
  import gc
  import os
  import shutil
  import subprocess
  import tempfile
  import warnings
  from abc import ABCMeta, abstractmethod
  import numpy
  from scipy.sparse import issparse, hstack
  from ..None import config
  from ..externals.joblib import Parallel, dump, load
  from ..utils import check_initialized
  from ..utils.exceptions import ParallelProcessingError, ParallelProcessingWarning
  from ..externals.sklearn.validation import check_random_state
label_desc: Use image node_id 6 for calling the BaseProcessor obj's underlying member method code with example usage: obj.clear() without return types