[R-sig-hpc] snow, socket cluster: problem with path to rscript

[Dirk Eddelbuettel]

On 15 April 2009 at 07:16, Dirk Eddelbuettel wrote:
| On 15 April 2009 at 17:29, Matthieu Stigler wrote:
| | >> So it is now working for the local computer with. However, when trying to
| | >> use the external computer, it seems to be working but nothing happens after
| | >> he asked for the last password...
| | >>     
| | >
| | > This tells you is that "something went wrong".  The basic strategy in this case
| | > is to use the "outfile" option to hopefully capture an error message.  You might
| | > need to set outfile differently for different slaves, particularly if
| | > you're starting
| | > more than one on the same machine, but I suggest just starting one slave
| | > on 210 to avoid the issue.  So do something like:
| | >
| | >   
| | >> host210 <- list(host = "mat at 192.100.100.210", rscript = "/usr/bin/Rscript",
| | >>     
| | > +                       outfile="/tmp/log.txt")
| | >   
| | >> cl2 <- makeCluster(list(host210), type = "SOCK")
| | >>     
| | >
| | >   
| | Ok, thanks for pointing out this methid.
| | 
| |  I tried it and got following error message. This does not seem not be 
| | computer specific (tried to do it to other host 213, and from other host 
| | 213 to 212, always same error message):
| | 
| | starting worker for ubuntu:10187 
| | 
| | Error in socketConnection(master, port = port, blocking = TRUE, open = "a+b") : 
| | 
| |   unable to open connection
| | 
| | Calls: local ... slaveLoop -> recvData -> makeSOCKmaster -> socketConnection
| | 
| | In addition: Warning message:
| | 
| | In socketConnection(master, port = port, blocking = TRUE, open = "a+b") :
| | 
| |   ubuntu:10187 cannot be opened
| | 
| | Execution halted
| | 
| | 
| | Is it related to ssh or snow? I did not find any reference to that prob 
| | googling for it...
| 
| Test for it --- can you actually issue an ssh command for the _script_ on the
| _machine_ you have specified ?  I.e. run
| 
| $ ssh mat at 192.100.100.210 /usr/bin/Rscript --version
| 
| where I added --version to make sure Rscript has something to do.  Unless
| this works 'by itself', you cannot expect to use it. 

That's what I get for posting before the coffee settles in. Thanks to Luke
for correcting the test for socket rather ssh connections.

Yet when I specify "SOCK" as type, I still get noise [1] from ssh:

> cl <- makeSOCKcluster(c("l1", "l2"))
Control socket connect(/home/deddelbuettel/.ssh/master-deddelbuettel at l1:22): Connection refused
ControlSocket /home/deddelbuettel/.ssh/master-deddelbuettel at l1:22 already exists, disabling multiplexing
Control socket connect(/home/deddelbuettel/.ssh/master-deddelbuettel at l2:22): Connection refused
ControlSocket /home/deddelbuettel/.ssh/master-deddelbuettel at l2:22 already exists, disabling multiplexing
> str(cl)
List of 2
 $ :List of 3
  ..$ con :Classes 'sockconn', 'connection'  atomic [1:1] 5
  .. .. ..- attr(*, "conn_id")=<externalptr>
  ..$ host: chr "l1"
  ..$ rank: int 1
  ..- attr(*, "class")= chr "SOCKnode"
 $ :List of 3
  ..$ con :Classes 'sockconn', 'connection'  atomic [1:1] 6
  .. .. ..- attr(*, "conn_id")=<externalptr>
  ..$ host: chr "l2"
  ..$ rank: int 2
  ..- attr(*, "class")= chr "SOCKnode"
 - attr(*, "class")= chr [1:2] "SOCKcluster" "cluster"
>

implying that you'd still want to sort out ssh access to the hosts even when
you use socket connections.

Dirk 
 
[1] I am using the following in ~/.ssh/config which can speed up multiple
connections to the same machines which is my use case at work:
-----------------------------------------------------------------------------
Host *
      ControlPath ~/.ssh/master-%r@%h:%p
      ControlMaster auto
      ForwardAgent yes
      ForwardX11 yes
      ForwardX11Trusted yes
-----------------------------------------------------------------------------


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