OSError: [Errno 12] Cannot allocate memory if too manay connect

[focalism]

If too many connections are established，get following trace

    return self.client.info()['commit_revision']
  File "/venv/local/lib/python2.7/site-packages/svn/common.py", line 86, in info
    do_combine=True)
  File "/venv/local/lib/python2.7/site-packages/svn/common.py", line 60, in run_command
    return self.external_command(cmd, environment=self.__env, **kwargs)
  File "/venv/local/lib/python2.7/site-packages/svn/common_base.py", line 29, in external_command
    universal_newlines=decode_text)
  File "/usr/lib/python2.7/subprocess.py", line 212, in check_output
    process = Popen(stdout=PIPE, *popenargs, **kwargs)
  File "/usr/lib/python2.7/subprocess.py", line 390, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 916, in _execute_child
    self.pid = os.fork()
OSError: [Errno 12] Cannot allocate memory

how to close the connections or is there have a close method