Server is running, but doesn't work and no response OR errors.

[fabdrol]

Server is running, but doesn't work and no response OR errors.

[squaremo]

Do you have the management UI available for the production rabbit? If so, you could check, while the listener and send are running,

1. there's at least two connections
2. there's an exchange called "foobar"
3. there's at least one anonymous queue (i.e., called amq-gen.)
4. the queue is bound to the exchange -- there's a little diagram which says the bindings

or since you have rabbitmqctl, you could try

rabbitmqctl list_connections
rabbitmqctl list_exchanges
rabbitmqctl list_queues
rabbitmqctl list_bindings

to get the same information.

[fabdrol]

@squaremo Thanks for your quick reply.
Here's the result. Seems like all connections are okay, exept maybe the "blocking" thing?
Listen.js still isn't receiving data... :(

root@vps20841:~/node# rabbitmqctl list_connections
Listing connections ...
guest   127.0.0.1   48329   blocked
guest   127.0.0.1   56268   blocked
guest   127.0.0.1   44985   blocked
guest   127.0.0.1   48339   blocked
guest   127.0.0.1   48335   blocked
guest   127.0.0.1   59207   blocked
guest   127.0.0.1   49693   blocked
guest   127.0.0.1   38669   blocked
guest   127.0.0.1   42090   blocked
guest   127.0.0.1   59367   blocked
guest   127.0.0.1   55873   blocked
guest   127.0.0.1   48338   blocked
guest   127.0.0.1   39871   blocked
guest   127.0.0.1   56802   blocked
guest   127.0.0.1   51745   blocked
guest   127.0.0.1   32970   blocked
guest   127.0.0.1   52902   blocked
guest   127.0.0.1   44522   blocked
guest   127.0.0.1   48351   blocked
guest   127.0.0.1   45223   blocked
guest   127.0.0.1   36377   blocked
guest   127.0.0.1   41351   blocked
guest   127.0.0.1   39465   blocked
guest   127.0.0.1   48512   blocked
guest   127.0.0.1   46911   blocked
guest   127.0.0.1   43706   blocked
guest   127.0.0.1   60939   blocked
guest   127.0.0.1   44780   blocked
guest   127.0.0.1   47939   blocked
guest   127.0.0.1   48350   blocking
guest   127.0.0.1   48330   blocked
guest   127.0.0.1   58946   blocked
guest   127.0.0.1   39132   blocked
guest   127.0.0.1   57959   blocked
guest   127.0.0.1   55610   blocked
guest   127.0.0.1   44325   blocked
guest   127.0.0.1   60704   blocked
guest   127.0.0.1   39505   blocked
guest   127.0.0.1   39560   blocked
guest   127.0.0.1   59698   blocked
guest   127.0.0.1   54807   blocked
guest   127.0.0.1   53337   blocked
guest   127.0.0.1   43231   blocked
guest   127.0.0.1   58111   blocked
guest   127.0.0.1   48336   blocked
guest   127.0.0.1   56431   blocked
guest   127.0.0.1   47084   blocked
guest   127.0.0.1   38705   blocked
guest   127.0.0.1   50742   blocked
guest   127.0.0.1   50534   blocked
guest   127.0.0.1   44785   blocked
guest   127.0.0.1   48332   blocked
guest   127.0.0.1   43799   blocked
guest   127.0.0.1   52334   blocked
guest   127.0.0.1   49425   blocked
guest   127.0.0.1   45581   blocked
guest   127.0.0.1   37266   blocked
guest   127.0.0.1   35015   blocked
guest   127.0.0.1   48204   blocked
guest   127.0.0.1   54950   blocked
guest   127.0.0.1   42833   blocked
guest   127.0.0.1   41091   blocked
guest   127.0.0.1   57612   blocked
guest   127.0.0.1   39818   blocked
guest   127.0.0.1   34384   blocked
guest   127.0.0.1   44064   blocked
guest   127.0.0.1   34022   blocked
guest   127.0.0.1   47832   blocked
...done.
root@vps20841:~/node# rabbitmqctl list_exchanges
Listing exchanges ...
foobar  fanout
amq.rabbitmq.trace  topic
amq.rabbitmq.log    topic
amq.match   headers
amq.headers headers
amq.topic   topic
amq.direct  direct
amq.fanout  fanout
    direct
app:events  fanout
...done.
root@vps20841:~/node# rabbitmqctl list_queues
Listing queues ...
amq.gen-A8zGHUad-iEEOFhlbqAkcS  0
...done.
root@vps20841:~/node# rabbitmqctl list_bindings
Listing bindings ...
    exchange    amq.gen-A8zGHUad-iEEOFhlbqAkcS  queue   amq.gen-A8zGHUad-iEEOFhlbqAkcS  []
foobar  exchange    amq.gen-A8zGHUad-iEEOFhlbqAkcS  queue       []
...done.
root@vps20841:~/node# 

[squaremo]

The exchanges, queues, and bindings all look fine from rabbit.js's point of view.

All those blocked connections though -- not sure what's going on there. RabbitMQ will block connections when it thinks it's going to run out of space to put messages; but, you have only one queue, and it has no messages. So it can hardly have run out. Do you mind if I post this to the rabbitmq mailing list to see what people make of it? Also not sure why so many connections -- are there other vhosts set up?

In the meantime, one way to check that it's the blocked connection that's keeping messages from getting through is to look at whether Node has to buffer things itself; an increasing context._connection.bufferSize will tell you that.

[squaremo]

Ah, looking at the rabbitmqctl status, it appears that RabbitMQ thinks there is about 200MB memory available to it. Does that sound right for the host you're using? I don't think RabbitMQ will handle running in that little memory gracefully; the memory alarm would constantly trigger, which would explain the blocked connections.

[squaremo]

You'll be able to tell if that's the case by looking at the logs (default locations given in http://www.rabbitmq.com/relocate.html).

The memory limit will appear in a line similar to

=INFO REPORT==== 29-Oct-2009::15:43:27 ===
Memory limit set to 2048MB.

and the alarm triggering will look like

=INFO REPORT==== 15-Sep-2010::14:53:44 ===
vm_memory_high_watermark set.
Memory used:53650536 allowed:52556595
=INFO REPORT==== 15-Sep-2010::14:53:44 ===
alarm_handler: {set,{vm_memory_high_watermark,[]}} 

[fabdrol]

hmm what would be a minimum of memory to run at? If RabbitMQ's memory footprint's too large, it might be wise to find another solution. My app is quite memory intensive...

[fabdrol]

I've moved to Redis pub/sub and increased my memory size. Thanks a lot for your help anyway. Even if I'd be able to get RabbitMQ working, I guess it's still overhead! (I'm already using Redis, and guaranteed delivery isn't necessery anyway)

[squaremo]

OK no worries -- sounds like the right thing to do. Hey do you think I should make rabbit.js work with Redis too? I'd have to change the name I guess ...

[fabdrol]

Haha, I don't know, maybe guaranteed delivery and stuff? Redis is blazingly fast, but it is also rather memory intensive if used on large scale... I wrote this really simple messenger based on redis: https://github.com/fabdrol/simplemessenger
btw, I suppose RabbitMQ also operates exclusively in memory.. the main benefit would be when you already use Redis, so there's less overhead

[squaremo]

RabbitMQ will put messages on disk if they are marked persistent (for recovery purposes), and it'll page queues out to disk when it starts running out of memory. The message index is in memory though, so there is a hard limit, unless you use the tokyo cabinet plugin to page the index out too. Mostly it likes to have things in memory, for sure.

I might try a redis context just to see what it's like.