running R commands asynchronously
On 06/10/2011 02:29 PM, Richard M. Heiberger wrote:
I am interested in running R commands asynchronously.
My first choice is in the same R session that I am currently in.
Here, the goal would be to run something like
RunAsynchSameSession(myfunction(), "outputname.rda")
Once RunAsynchSameSession had started myfunction(),
RunAsynchSameSession would complete immediately. myfunction would
keep going. It is OK if execution of the myfunction() command
prevents new input to R until it has completed. The important feature
is that RunAsynchSameSession must tell the progam that called it that
it was done.
somewhere in-between, starting a new R session but keeping the
communication within the original.
library(snow)
cl <- makeSOCKcluster("localhost")
sendCall(cl[[1]], function(n) { Sys.sleep(n); n }, list(n=5))
## do other things here...
recvResult(cl[[1]]) ## blocks until result available
I had hoped that I could open a non-blocking connection on the master
(blocking=FALSE in the next-to-last line of newSOCKnode) and then poll
with isIncomplete(cl[[1]]$con) but I couldn't get this to work (the
connection, or more likely my understanding, seemed to be blocking anyway).
sendCall(cl[[1]], function(n) { Sys.sleep(n); n }, list(n=5))
while(isIncomplete(cl[[1]]$con))
cat("tick\n") ## not printed
recvResult(cl[[1]])
This approach might also work with the multicore package.
Martin
Second choice is to start an independent process, BATCH or something
similar, and save the resulting data objects in an .rda file.
RunAsynchBatch("myfile.r", "outputname.rda")
The RunAsynchBatch would start a batch process and complete
immediately after starting the batch file. The batch file would run
independently until it was completed. While I know how to do this,
for example with system(wait=FALSE), I would appreciate seeing a
worked collection of statements, including getting outputname.rda back
to the original R session. I am working on Windows.
Rich
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