Michael: I don't see any comments on Bug 17432 ( https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=17432) later than June 1, 2018. Would you please supply a link pointing to the followup to this discussion on bugzilla?
Thanks. Jen. > On Thu Sep 13 14:14:46 CEST 2018 Michael Lawrence wrote: > > Thanks, I responded to this on bugzilla. > On Wed, Sep 12, 2018 at 9:04 AM Chris Culnane > <christopher.culnane using unimelb.edu.au> wrote: > > > > Bug 17432 (https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=17432) is still a problem when using pipes for IPC. > > > > The bug is evident when calling R from another process and trying to communicate via StdIn. R will buffer the input and not read lines until the buffer is exceeded or StdIn is closed by the sending process. This prevents interactive communication between a calling process and a child R process. > > > > From a quick look at the source code, it looks like the bug is caused by only disabling buffering when isatty() returns true for a file descriptor (connections.c). This fixes the original bug when the script is run in a terminal, but doesn't help for pipes, which will return false for isatty(). > > > > An example R script and python script are provided to demonstrate the problem: > > > > R script (example.r): > > ================ > > f <- file("stdin") > > open(f) > > while(length(line <- readLines(f,n=1)) > 0) { > > write(line, stderr()) > > } > > > > Python3 script: > > ============ > > import sys, os, subprocess > > process = subprocess.Popen(['Rscript', 'example.r'], stdin=subprocess.PIPE, stdout=subprocess.PIPE) > > for line in sys.stdin: > > process.stdin.write((line + '\n').encode('utf-8')) > > process.stdin.flush() > > > > > > Expected Behaviour: > > Run python script, each line entered is echoed back immediately by the R script - which is what happens on 3.4.4 > > > > Observed Behaviiour on >=3.5.0 (include devel): > > The R script does not process lines as they are sent, it only receives them when StdIn is closed. > > > > > > Best Regards > > > > Chris [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
