[Pkg-xfce-devel] Bug#360533: xfce4-terminal: scrollback on long output without newlines is very slow

[Michael Gilbert]

Package: xfce4-terminal
Version: 0.2.4-7
Severity: normal

if the output of a program is a long list of data that does not consist 
of newlines, xfce terminal will be very slow.  gnome terminal gets 
around this limitation by limiting the scrollback in terms of bytes, 
rather than line numbers.  for example, 1000 lines of scrollback would 
be limited to something like 80*1000 = 80,000 bytes of scrollback 
instead of 1000 newlines.

the following code (which computes the largest known prime and outputs
that number to stdout; http://fabrice.bellard.free.fr/mersenne.html)
is a demonstration of this bug.  the output causes xfce terminal to
practically grind to a halt.  the problem arises because the output
contains no newlines.  the computation itself only takes about 3 minutes
on my 1.6 GHz processor:

#!/bin/bash

echo '''#include <stdio.h>
int 
m=754974721,N,t[1<<24],a,*p,i,e=30611555,j,s,c,U;f(d){for(s=1<<24;s/=2;d=d*
1LL*d%m)if(s<N)for(p=t;p<t+N;p+=s)for(i=s,c=1;i;i--)a=*p+p[s],p[s]=(m+*p-p[s])*1LL
*c%m,*p++=a%m,c=c*1LL*d%m;for(j=0;i<N-1;){for(s=N/2;!((j^=s)&s);s/=2);if(++i<j)
a=t[i],t[i]=t[j],t[j]=a;}}main(){*t=2;U=N=1;while(e/=2){N*=2;U=U*1LL*(m+1)/2%m;f
(362);for(p=t;p<t+N;p++)*p=*p*1LL**p%m*U%m;f(415027540);for(a=0,p=t;p<t+N;)a+=*p
<<(e&1),*p++=a%10,a/=10;}while(!*--p);t[0]--;while(p>=t)printf("%d",*p--);}''' 
> largest-known-prime.c

gcc -o largest-known-prime largest-known-prime.c
../largest-known-prime

-- System Information:
Debian Release: testing/unstable
  APT prefers testing
  APT policy: (600, 'testing'), (500, 'unstable')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.15-1-686
Locale: LANG=en_US, LC_CTYPE=en_US (charmap=ISO-8859-1)

Versions of packages xfce4-terminal depends on:
ii  libatk1.0-0       1.10.3-1               The ATK accessibility toolkit
ii  libc6             2.3.6-3                GNU C Library: Shared libraries an
ii  libcairo2         1.0.2-3                The Cairo 2D vector graphics libra
ii  libdbus-1-2       0.61-5                 simple interprocess messaging syst
ii  libdbus-glib-1-2  0.61-5                 simple interprocess messaging syst
ii  libexo-0.3-0      0.3.1.4alpha2-r20235-1 Library with extensions for Xfce
ii  libfontconfig1    2.3.2-1.1              generic font configuration library
ii  libfreetype6      2.1.10-1               FreeType 2 font engine, shared lib
ii  libglib2.0-0      2.10.1-2               The GLib library of C routines
ii  libgtk2.0-0       2.8.13-1               The GTK+ graphical user interface 
ii  libice6           6.9.0.dfsg.1-4         Inter-Client Exchange library
ii  libncurses5       5.5-1                  Shared libraries for terminal hand
ii  libpango1.0-0     1.12.0-2               Layout and rendering of internatio
ii  libpng12-0        1.2.8rel-5             PNG library - runtime
ii  libsm6            6.9.0.dfsg.1-4         X Window System Session Management
ii  libstartup-notifi 0.8-1                  library for program launch feedbac
ii  libvte4           1:0.11.20-3            Terminal emulator widget for GTK+ 
ii  libx11-6          6.9.0.dfsg.1-4         X Window System protocol client li
ii  libxcursor1       1.1.3-1                X cursor management library
ii  libxext6          6.9.0.dfsg.1-4         X Window System miscellaneous exte
ii  libxfce4util-1    4.2.3.2-1              Utility functions library for Xfce
ii  libxfcegui4-3     4.2.3-1                Basic GUI C functions for Xfce4
ii  libxft2           2.1.8.2-3              FreeType-based font drawing librar
ii  libxi6            6.9.0.dfsg.1-4         X Window System Input extension li
ii  libxinerama1      6.9.0.dfsg.1-4         X Window System multi-head display
ii  libxrandr2        6.9.0.dfsg.1-4         X Window System Resize, Rotate and
ii  libxrender1       1:0.9.0.2-1            X Rendering Extension client libra
ii  zlib1g            1:1.2.3-11             compression library - runtime

Versions of packages xfce4-terminal recommends:
ii  dbus-1-utils                  0.23.4-8   simple interprocess messaging syst

-- no debconf information