[R] package Parallel - accessing remote cores on Windows using plink (PuTTY)
Dylan.Tevlin at kochind.com
Fri Sep 19 16:49:36 CEST 2014
My system information:
R 2.14.1 x64
I'm attempting to access cores on other machines in my LAN. As setup, I can ping all the machines successfully and it's a private office network where I have access to all computers, so there really shouldn't be any problems arising from the network itself.
All machines I am connecting to have identical system information.
I issue the following command to make a connection to the remote machine and access one of its cores.
cl<-makePSOCKcluster(c(remoteHostIP), rshcmd="plink", outfile="")
The parallel package, to make remote connections, issues a system command (found in the file snowSOCK.R, function newPSOCKnode of the source) of the following form on the remote machine
ssh -l user otherhost '/usr/lib/R/bin/Rscript' -e 'parallel:::.slaveRSOCK()' MASTER=myhost PORT=10187 OUT=/dev/null TIMEOUT=2592000 METHODS=TRUE XDR=TRUE
Where the specific command (ssh) can be specified by the rshcmd parameter of the command makePSOCKcluster. Given that a command such as ssh must be present on the machine, I installed PuTTY on both the master and host, and added the pertinent path to the system PATH variable so that plink is always accessible from the command line. I'm not set on PuTTY, it's just free and I've used it before.
Here are my two cases. If I issue my above command, the process hangs indefinitely. If I set the manual flag equal to TRUE, as in the following
cl<-makePSOCKcluster(c(remoteHostIP), rshcmd="plink", outfile="", manual=TRUE)
I'm able to make the connection to the remote host just fine. This indicates to me that there is something wrong with the system command that is being issued with manual=FALSE (the default).
Another problem with this is that it is seemingly very hard to test, as the hanging process gives me no information on what is actually occurring. Has anyone had any success with this? Are there any ideas on steps I could take to fix or debug this issue?
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