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engineyard-visualvm is a command-line utility for use with JRuby and Engine Yard Cloud that makes it easy to connect Visual VM on a desktop to a running JRuby or Java process in EY Cloud.


To start Visual VM on your local machine to an already-running process:

# Connect by EY Cloud environment and account
$ ey-visualvm start --environment=jruby --account=example

(If you need to see a list of available environments and their associated accounts, use the ey environments command from the engineyard gem.)

You can also use the engineyard-visualvm gem to connect Visual VM to any host where you have an available ssh connection.

# Connect by hostname:
$ ey-visualvm start      

To connect to a server, the server must be booted with some additional JVM arguments. These can be generated on the server side with:

$ ey-visualvm jvmargs
-Dorg.jruby.ext.jmx.agent.port=5900 -javaagent:/path/to/engineyard-visualvm/agent.jar

The server JVM binds to the loopback interface and listens on port 5900 by default. If you want to use a different interface and/or port than the default, pass --host=<host-or-ip> or --port=<port> to ey-visualvm jvmargs.

Acceptance Test

To verify that a JMX connection to a server can be established, we can use Vagrant and Chef to bootstrap a VM, start a JRuby process with JMX enabled, create an ssh tunnel to the Vagrant box, and use the jmx gem to connect to it from Ruby code. The code for this looks like this:

require 'childprocess'
require 'jmx'

sh "vagrant ssh_config > ssh_config.tmp"
sh "vagrant up"
at_exit { sh "vagrant halt"; rm_f "ssh_config.tmp" }

@host, @port = 'localhost', 5900

ssh ="ssh", "-NL", "#{@port}:#{@host}:#{@port}", "-F", "ssh_config.tmp", "default")
at_exit { ssh.stop }

require 'engineyard-visualvm'
include EngineYard::VisualVM::Helpers
server = jmx_service_url

runtime_config_name = server.query_names('org.jruby:type=Runtime,name=*,service=Config').to_a.first
puts "Found runtime #{runtime_config_name}"
runtime_config = server[runtime_config_name]
puts "Runtime version: #{runtime_config['VersionString']}"
puts "OK"

To try it yourself, do the following:

# Ensure you have vagrant and jmx installed
$ bundle install

# Run the acceptance test
$ rake acceptance
vagrant ssh_config > ssh_config.tmp
vagrant up
# ... bunch of output as the VM boots and Chef runs...
[default] [Tue, 22 Nov 2011 19:52:41 -0800] INFO: execute[start server] ran successfully
[Tue, 22 Nov 2011 19:52:41 -0800] INFO: Chef Run complete in 35.157236 seconds
[Tue, 22 Nov 2011 19:52:41 -0800] INFO: Running report handlers
[Tue, 22 Nov 2011 19:52:41 -0800] INFO: Report handlers complete
: stdout
Found runtime org.jruby:type=Runtime,name=25292276,service=Config
Runtime version: jruby 1.6.5 (ruby-1.8.7-p330) (2011-10-25 9dcd388) (Java HotSpot(TM) Client VM 1.6.0_26) [linux-i386-java]
vagrant halt
[default] Attempting graceful shutdown of linux...
rm -f ssh_config.tmp

Bits and Pieces


  • Prompt for a JVM to connect to if more than one JVM process is running on the server
  • Prompt for an instance to connect to if the environment has multiple instances
  • Data collected by jstatd is not yet supported, so things like the Visual GC tab are not supported yet.
  • Additional utilities to make use of the JMX connection remotely