[Bug 97574] High CPU utilization with long lines in backscroll locks gnome-terminal

[Tod Hagan]

Public bug reported:

Binary package hint: gnome-terminal

Version: Edgy, 2.16.1-0ubuntu1

Steps to reproduce:

1. Open new window
2. Maximize it (197 columns, 64 lines)
3. Set scrollback to 1500 lines (955K)
4. Fill the backscroll with a long line by doing perl -e 'print join("",map{sprintf("%020d",$_)}1..$ARGV[0])' 5000

At this point CPU utilization goes to 100% when performing any operation
affecting the window's main client area, such as mousing over the
window, opening a menu,  switching between adjacent menus, and
particularly, selecting a range of text. gnome-terminal is completely
unresponsive while the CPU is pegged. Vary the '5000' argument to the
perl command in step 4 to adjust for CPU speed.

This is on an AMD Athlon(tm) 64 Processor 3200+. 7 gnome-terminal
windows displaying a total of 22 tabs were open before performing the
above steps.

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                                      
 5087 tod       18   0  182m  94m  12m R 97.2  4.6  35:22.07 gnome-terminal

Note that this may become worse with use -- I was motivated to report
this when a buggy script produced a very long single line of output
which hung all gnome-terminal windows for ~20 seconds. This was on a
window with 7 tabs that had been open and in use for several days.

** Affects: gnome-terminal (Ubuntu)
     Importance: Undecided
         Status: Unconfirmed

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High CPU utilization with long lines in backscroll locks gnome-terminal
https://launchpad.net/bugs/97574