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bug#18626: 24.3.94; communication with subprocess is slow
From: |
Stephen Leake |
Subject: |
bug#18626: 24.3.94; communication with subprocess is slow |
Date: |
Sun, 05 Oct 2014 08:41:08 -0500 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (windows-nt) |
Stephen Leake <stephen_leake@stephe-leake.org> writes:
> Eli Zaretskii <eliz@gnu.org> writes:
>
>> Can you present similar timings from some Posix platform for
>> comparison?
>
> On Debian wheezy, with emacs 24.3.94:
>
> $ cd /tmp
> $ time cat < /home/Projects/emacs/emacs-24.3.94/src/xdisp.c > xdisp.c
> real 0m0.007s
> user 0m0.000s
> sys 0m0.004s
>
>
> (find-file "emacs-24.3.94/src/xdisp.c")
> (pipe-torture "cat.exe")
> 1.556597
>
> much faster than Windows, but still slow relative to plain file IO.
>
> (pipe-torture "debug.exe" "4096")
>
> This dies, because "debug.exe" exits early. It turns out that Emacs is
> sending one line of the buffer at a time. I have not yet tried to figure
> out why that doesn't happen on Windows.
I rewrote debug.adb to handle this case by exiting when the total bytes
read equals the file size:
with Ada.Command_Line;
with Ada.Text_IO; use Ada.Text_IO;
with GNAT.OS_Lib;
procedure Debug_Counted
is
use GNAT.OS_Lib;
Chunk : constant Integer := Integer'Value (Ada.Command_Line.Argument
(1));
File_Size : constant Integer := Integer'Value (Ada.Command_Line.Argument
(2));
File : constant File_Descriptor := GNAT.OS_Lib.Standin;
Read_Bytes : Integer;
Total_Read_Bytes : Integer := 0;
Text : aliased String (1 .. Chunk);
Short_Count : Integer := 0;
Count : Integer := 0;
begin
loop
Read_Bytes := Read (File, Text'Address, Chunk);
Total_Read_Bytes := Total_Read_Bytes + Read_Bytes;
if Read_Bytes < Chunk then
Short_Count := Short_Count + 1;
else
Count := Count + 1;
end if;
exit when Total_Read_Bytes >= File_Size;
end loop;
Put_Line ("Short_Count => " & Integer'Image (Short_Count) & " Count => " &
Integer'Image (Count));
end Debug_Counted;
(find-file "xdisp.c")
(pipe-torture
"/home/Projects/org.emacs.ada-mode.stephe-1/build/wisi/debug_counted"
"4096" "974230")
0.344027
This is comparable to the time on Windows with a large buffer in the
subprocess. So apparently it is not using the same delay in
send_process. Or the IO system is providing a large buffer.
--
-- Stephe
bug#18626: 24.3.94; communication with subprocess is slow, Stephen Leake, 2014/10/04
- bug#18626: 24.3.94; communication with subprocess is slow, Eli Zaretskii, 2014/10/04
- bug#18626: 24.3.94; communication with subprocess is slow, Stephen Leake, 2014/10/05
- bug#18626: 24.3.94; communication with subprocess is slow, Eli Zaretskii, 2014/10/05
- bug#18626: 24.3.94; communication with subprocess is slow, Stephen Leake, 2014/10/05
- bug#18626: 24.3.94; communication with subprocess is slow, Eli Zaretskii, 2014/10/05