Gather consumer channel information from RabbitMQ in order to troubleshoot an issue with unexpected unacknowledged messages

Readme.md

Instructions

1. Copy the provided script (gatherChannelInfo.erl) onto one of the rabbitmq vms
   e.g.

bosh -d <yourDeploymentName> scp gatherChannelInfo.erl rmq/b9b26ca8-6a15-4bf6-9881-68486042f46b:/tmp/gatherChannelInfo.erl

1. Ssh onto the same rabbitmq vms and switch to root (sudo -i)
   e.g.

bosh -d <yourDeploymentName> ssh rmq/b9b26ca8-6a15-4bf6-9881-68486042f46b

2. Make sure erl is on the path

which erl

3. Run the following command to connect to one of the erlang VMs:

erl -sname "remsh-1" -hidden -remsh "$RABBITMQ_NODENAME"

4. Copy and paste this command onto the erl shell:

c("/tmp/gatherChannelInfo", [{outdir, "/tmp"}] ).

5. Copy and paste this command onto the erl shell. Replace VirtualHost(e.g./) and queue name (e.g.test-1) with yours.

gatherChannelInfo:main(<<"/">>, <<"test-1">>).

6. Send us the outcome from the last command

7. To exit from erl shell : ^g q Enter

gatherChannelInfo.erl

-module(gatherChannelInfo).

-export([main/2]).
-import(io, [format/1]).

find(What, List) ->
  hd([ Value || {Key, Value} <- List, Key =:= What]).

main(VirtualHost, QueueName) ->
  %% Get queue information
  Queue = erlang:process_info(rabbit_amqqueue:pid_of(VirtualHost, QueueName), dictionary),
  io:format("Queue ~p on ~p information ~n ~p~n", [QueueName, VirtualHost, Queue]),
  io:format("-----------------------------------~n"),

  ChannelPids = [X || { {ch, X}, _} <- element(2,Queue)],

  %% Print acktags and unsent_message_count from each channel bound to the queue
  ChannelDetails = [ { Pid, AckTags, Unsent } || { {ch, Pid}, {cr, _, _, AckTags, _, _, _, Unsent}} <- element(2,Queue)],
  io:format("Channel consumer details ~n  ~p~n", [ChannelDetails]),
  io:format("-----------------------------------~n"),

  %% Get channel information bound to a queue called test-1
  ChannelInfos = [rabbit_channel:info(X) || X <- ChannelPids],
  Channels = [erlang:process_info(X) || X <- ChannelPids],

  io:format("Channel info ~n  ~p~n", [ChannelInfos]),
  io:format("-----------------------------------~n"),

  io:format("Channel Processes ~n  ~p~n", [Channels]),
  io:format("-----------------------------------~n"),

  %% Get connection information associated to those channels.
  Connections = [ erlang:process_info(X) || X <- sets:to_list(sets:from_list([ find(connection,X) || X <- ChannelInfos])) ],

  io:format("Connection Processes ~n  ~p~n", [Connections]).