[Rd] reading data from a pipe() uses 99% CPU (PR#7634)

[keith at nissimo.net]

Full_Name: Keith L. Frost
Version: R 2.0.1 (Rgui -- Win32)
OS: Windows XP Pro SP2
Submission from: (NULL) (66.162.141.10)


There seems to be a bug in the Win32 implementation of reading data from another
process
which has been started from the pipe() call.  The other process gets starved for
CPU
time --- it takes well over ten times as long to complete as it would if running
from
the same pipe() call, if only the calling (R) process did not read from the
pipe.  I
have tried using readLines() and scan(), and both have the same effect.

This bug seems to be OS-specific:  I have not observed this behavior under
Linux.