emacs communication with subprocess is slow

[Stephen Leake <stephen_leake@stephe-leake.org>]

This may be related to http://debbugs.gnu.org/cgi/bugreport.cgi?bug=18420

I'm using Emacs pretest 24.3.93, with the patch from 18240, on Windows 7.

I've run into another problem with Emacs communication with external
processes; there seems to be a delay on every task switch. This shows up
both when sending data to the subprocess, and when reading from it.

I haven't tested this on Debian yet.

The delay is not present in Emacs 24.3 on Windows 7.

When sending the contents of an Emacs buffer (source code to be parsed)
to the subprocess, if the read buffer in the subprocess is
large enough to hold the entire contents, no delay is apparent. However,
if the buffer is smaller, so that several reads are needed, then a delay
appears. 

Similarly when sending data from the subprocess to Emacs.

I suspect this doesn't show up with the 'cat' test in 18420 because cat
uses multimegabyte buffers; it's designed for copying gigabyte files.

I can use a large buffer in my subprocess for read as a workaround, but
I have no control over the read buffer in Emacs (perhaps that could be
added?).

Should I reopen 18240, or start a new bug?

-- 
-- Stephe