This simple batch file in relatively short order consumes all available memory on Windows 7 (x64). What's going on? and what precautions can be taken to ward against it?

any-invalid-command-you-like-here ^

Apparently necessary preconditions to exhibit the effect:

  • the caret ^ is the very last thing in the file, and the script is not terminated with a newline
  • the caret is preceded by at least 2 spaces or characters, e.g. if the dots in the following represent spaces the memory leak will not be triggered .^, while this one will ..^ (just slowly)

In this Process Explorer screen shot, the script had been running about 30 seconds, consumed 2.9GB, and was still climbing at a steady rate:

2.9GB memory consumed and still climbing

If you're going to experiment with this, make sure you can get at the Close Window [X] control or have a Task Manager or Process Explorer fired up and ready as Ctrl-C, Ctrl-Break, Alt-F4 have no effect.

It appears multiple carets will cause the memory usage to ramp up much more quickly. The first time I encountered this there wasn't enough memory available in 1 or 2 minutes to do simple things like Alt-Tab and even the 3 finger salute Ctrl-Alt-Del was ineffective. I had to hard power off the machine.

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