The actual bug corresponding to this thread is: https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17470 On Fri, Sep 14, 2018 at 9:22 AM Jennifer Lyon <jennifer.s.l...@gmail.com> wrote: > > 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 > >
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