'Shrink worker\'s pool
**Example request**:
.. sourcecode:: http
POST /api/worker/pool/shrink/celery@worker2 HTTP/1.1
Content-Length: 0
Host: localhost:5555
**Example response**:
.. sourcecode:: http
HTTP/1.1 200 OK
Content-Length: 60
Content-Type: application/json; charset=UTF-8
"message": "Shrinking \'celery@worker2\' worker\'s pool by 1"
:query n: number of pool processes to shrink, default is 1
:reqheader Authorization: optional OAuth token to authenticate
:statuscode 200: no error
:statuscode 401: unauthorized request
:statuscode 403: failed to shrink
:statuscode 404: unknown worker'

@web.authenticated
def post(self, workername):

    if (not self.is_worker(workername)):
        raise web.HTTPError(404, ("Unknown    worker    '%s'" % workername))
    n = self.get_argument('n', default=1, type=int)
    logger.info("Shrinking    '%s'    worker's    pool    by    '%s'", workername, n)
    response = self.capp.control.pool_shrink(n=n, reply=True, destination=[workername])
    if (response and ('ok' in response[0][workername])):
        self.write(dict(message=("Shrinking    '%s'    worker's    pool    by    %s" % (workername, n))))
    else:
        logger.error(response)
        self.set_status(403)
        self.write(("Failed    to    shrink    '%s'    worker's    pool:    %s" % (workername, self.error_reason(workername, response))))
