Forum: Ruby Accessing Ruby Object in Memory

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112b68b29c51d07c738d8f58e38f4d2d?d=identicon&s=25 Bryan Richardson (btrichardson)
on 2008-10-13 19:42
Hello all,

I have a long running Ruby simulation in which data is stored to Ruby
hashes throughout the simulation.  I'd like to be able to access the
hashes in memory from another Ruby script while the simulation is still
running to see what the progress of the simulation is (rather than
printing to the screen, using log4r, etc.  Is this possible?  If so, any
suggestions how to do so?

--
Thanks!
Bryan
Da33a4ac652c1c8900392a8599206640?d=identicon&s=25 Thomas B. (tpreal)
on 2008-10-13 19:50
Bryan Richardson wrote:
> Hello all,
>
> I have a long running Ruby simulation in which data is stored to Ruby
> hashes throughout the simulation.  I'd like to be able to access the
> hashes in memory from another Ruby script while the simulation is still
> running to see what the progress of the simulation is (rather than
> printing to the screen, using log4r, etc.  Is this possible?  If so, any
> suggestions how to do so?

Hello. I guess this is not possible, and even if it is, it is not a good
idea to do this. Probably a much better idea would be to start a TCP
server in the daemon, and connect to it from the other program, and
communicate using some simple protocol. Another idea could be to write
some progress info into a file, and open the file from the other
process, but then you'll have to handle some concurrency problems (not
very hard, I guess, it will be enough to wait a moment and retry on file
opening failure). But still I think the server is a better and more
standard way to do this. Have a look at TCPServer and TCPSocket in
'socket', it is not hard.

TPR.
47b1910084592eb77a032bc7d8d1a84e?d=identicon&s=25 Joel VanderWerf (Guest)
on 2008-10-13 21:22
(Received via mailing list)
Thomas B. wrote:
> Hello. I guess this is not possible, and even if it is, it is not a good
> idea to do this. Probably a much better idea would be to start a TCP
> server in the daemon, and connect to it from the other program, and
> communicate using some simple protocol. Another idea could be to write
> some progress info into a file, and open the file from the other
> process, but then you'll have to handle some concurrency problems (not
> very hard, I guess, it will be enough to wait a moment and retry on file
> opening failure). But still I think the server is a better and more
> standard way to do this. Have a look at TCPServer and TCPSocket in
> 'socket', it is not hard.

DRb is the canonical way of doing this if both processes are ruby
programs. For example:

== server.rb ==
require 'drb'

uri = "drbunix:/tmp/my-simulation.sock" # use "localhost:4444" on win
h = {1=>2, 3=>4}
DRb.start_service(uri, h)
DRb.thread.join

== client.rb ==
require 'drb'

uri = "drbunix:/tmp/my-simulation.sock" # use "localhost:4444" on win
DRb.start_service(nil, nil)
server_object = DRbObject.new(nil, uri)

p server_object.keys
server_object.each do |k, v|
   p [k, v]
end

================
Output:

[1, 3]
[1, 2]
[3, 4]
E0d864d9677f3c1482a20152b7cac0e2?d=identicon&s=25 Robert Klemme (Guest)
on 2008-10-13 21:25
(Received via mailing list)
On 13.10.2008 19:39, Bryan Richardson wrote:
> I have a long running Ruby simulation in which data is stored to Ruby
> hashes throughout the simulation.  I'd like to be able to access the
> hashes in memory from another Ruby script while the simulation is still
> running to see what the progress of the simulation is (rather than
> printing to the screen, using log4r, etc.  Is this possible?  If so, any
> suggestions how to do so?

Please look into DRb.  For pure status updates I would push the current
state to the other process as opposed to pulling it because this does
not need synchronization in the simulation.  You can find a working toy
example attached.

Kind regards

  robert
47b1910084592eb77a032bc7d8d1a84e?d=identicon&s=25 Joel VanderWerf (Guest)
on 2008-10-13 21:35
(Received via mailing list)
Two addenda:

1. if the comm seems slow, try setting

Socket.do_not_reverse_lookup = true

2. the url for windows (and other tcp) should be:

uri = "druby://localhost:4444"


So here's the example again:

== server.rb ==
require 'drb'

Socket.do_not_reverse_lookup = true

uri = "druby://localhost:4444"
h = {1=>2, 3=>4}
DRb.start_service(uri, h)
DRb.thread.join

== client.rb ==
require 'drb'

Socket.do_not_reverse_lookup = true

uri = "druby://localhost:4444"
DRb.start_service(nil, nil)
server_object = DRbObject.new(nil, uri)

p server_object.keys
server_object.each do |k, v|
   p [k, v]
end
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