Eli Zaretskii writes: >> From: Joseph Mingrone >> Date: Fri, 24 Aug 2018 21:59:48 -0300 >> Here is a recipe to make Emacs (nearly) hang indefinitely. >> 1. emacs -Q >> 2. Visit the file found https://ftfl.ca/misc/big_file_hangs_emacs.txt >> 3. M-x toggle-truncate-lines >> 4. Use rectangle-mark-mode (C-x SPC) to mark the rectangle that starts >> at the top left of the file (point 1), and includes the leading white >> space, the line numbers, and the space after the line numbers (point >> 468848). >> 5. Kill the rectangle with C-x r k. >> For me, the Emacs process will continue to use 100% CPU and Emacs is >> almost completely unresponsive and has to be killed. Some actions such >> as saving the file may complete, but only after a few minutes. > It doesn't hang, it just takes very long to finish that operation (3 > min on my machine with an unoptimized build; should be something like > 1 to 1.5 min in an optimized build). > This belongs to the "Emacs is very slow with long lines" class of > problems: the file has 2900-character lines. If this file will never > include any text, I suggest to visit it with > "M-x find-file-literally", then the problem of slowness will go away. Thanks for the `find-file-literally' tip. The rectangle does eventually get cut for me as well. Ignoring speed, the problem is that Emacs is unusable afterwards. For example, if I go away for an hour or so, then return, the Emacs process will still be using something close to 100% CPU and trying to doing something simple, like moving the point forward, may take minutes.