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Logical Bombs for Fun and Benchmarking

Explosive Code

Article from ADMIN 53/2019

By Federico Lucifredi

The admin can generate load a number of ways with shell commands.

In this column, I often make use of the stress [1] utility as a convenient way to generate load on a system's memory, CPU, or storage subsystem. Although not the most sophisticated of tools, load generators like stress are simple to use and effective, because they provide a convenient way to load a certain number of CPU cores or to fill a predefined amount of RAM and do so in a manner that can be reproduced with consistency. However, you can find other minimalist ways to generate load easily with shell commands. For example, with

$ yes > /dev/null &

the yes [2] command repeatedly outputs a string until killed and would normally be bound by the I/O speed of the terminal. Because the output is redirected into the oblivion that is /dev/null before it ever reaches the screen buffers, each such invocation is essentially a pure processor workload that will maximally use up to one CPU core while taking up close to zero I/O or memory resources.

The top [3] command displays a perfect 1.00 load average after one minute (Figure 1). Amazon CloudWatch [4] data for this test instance more slowly converges on 100% CPU, consistent with the single vCPU configuration of a t2.micro instance (Figure 2).

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