text: #!/usr/bin/env python3
  # -*- encoding: utf-8 -*-
  
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  #  or more contributor license agreements.  See the NOTICE file
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  #  to you under the Apache License, Version 2.0 (the
  #  "License"); you may not use this file except in compliance
  #  with the License.  You may obtain a copy of the License at
  #
  #    http://www.apache.org/licenses/LICENSE-2.0
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  #  Unless required by applicable law or agreed to in writing,
  #  software distributed under the License is distributed on an
  #  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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  """ jmaphandler.py """
  import json
  import traceback
  import tornado.gen
  import tornado.web
  
  from heron.common.src.python.utils.log import Log
  from heron.tools.tracker.src.python import utils
  from heron.tools.tracker.src.python.handlers import BaseHandler
  from heron.tools.tracker.src.python.handlers.pidhandler import getInstancePid
  
  class JmapHandler(BaseHandler):
    """
    URL - /topologies/jmap?cluster=<cluster>&topology=<topology> \
          &environ=<environment>&instance=<instance>
    Parameters:
     - cluster - Name of cluster.
     - role - (optional) Role used to submit the topology.
     - environ - Running environment.
     - topology - Name of topology (Note: Case sensitive. Can only
                  include [a-zA-Z0-9-_]+)
     - instance - Instance Id
  
    Issue a jmap for instance and save the result in a file like
    /tmp/heap.bin
    The response JSON is a dict with following format:
    {
       'command': Full command executed at server.
       'stdout': Text on stdout of executing the command.
       'stderr': <optional> Text on stderr.
    }
    """
  
    # pylint: disable=attribute-defined-outside-init
    def initialize(self, tracker):
      """ initialize """
      self.tracker = tracker
  
    @tornado.gen.coroutine
    def get(self):
      """ get method """
      try:
        cluster = self.get_argument_cluster()
        role = self.get_argument_role()
        environ = self.get_argument_environ()
        topology_name = self.get_argument_topology()
        instance = self.get_argument_instance()
        topology_info = self.tracker.get_topology_info(topology_name, cluster, role, environ)
        ret = yield self.runInstanceJmap(topology_info, instance)
        self.write_success_response(ret)
      except Exception as e:
        Log.debug(traceback.format_exc())
        self.write_error_response(e)
  
    # pylint: disable=no-self-use
    @tornado.gen.coroutine
    def runInstanceJmap(self, topology_info, instance_id):
      """
      Fetches Instance jstack from heron-shell.
      """
      pid_response = yield getInstancePid(topology_info, instance_id)
      try:
        http_client = tornado.httpclient.AsyncHTTPClient()
        pid_json = json.loads(pid_response)
        pid = pid_json['stdout'].strip()
        if pid == '':
          raise Exception('Failed to get pid')
        endpoint = utils.make_shell_endpoint(topology_info, instance_id)
        url = "%s/jmap/%s" % (endpoint, pid)
        response = yield http_client.fetch(url)
        Log.debug("HTTP call for url: %s", url)
        raise tornado.gen.Return(response.body)
      except tornado.httpclient.HTTPError as e:
        raise Exception(str(e))
  