Benchmark of file and image generation

Benchmark protocol

This is a benchmark designed to test how fast WeeWX generates the files and images of the Seasons skin, using one year of data.

Download and unpack the benchmark:

cd /var/tmp
wget -O weewx-benchmark-master.tar.gz https://github.com/weewx/weewx-benchmark/archive/master.tar.gz
tar xvf weewx-benchmark-master.tar.gz

This benchmark will work as is for Version 5.0.0b13 or later. However, for earlier versions you must make two modifications in the configuration file weewx.conf:
- Set WEEWX_ROOT to the location of the benchmark:
```
WEEWX_ROOT=/var/tmp/weewx-benchmark-master
```
- Set SQLITE_ROOT to the location of the archive directory:
```
SQLITE_ROOT=/var/tmp/weewx-benchmark-master/archive
```
Because this test is of how long it takes to create and populate the subdirectory weewx-benchmark-master/public_html, it must be empty before you start.
```
rm -r weewx-benchmark-master/public_html
```
If you are on a laptop, plug it in!
Run the benchmark. For Version 5, use weectl report. For Version 4, use wee_reports
```
weectl report run --config weewx-benchmark-master/weewx.conf
```
The benchmark will print the generation time for the files and images to standard output. Make sure there are 21 files and 68 images. If not, there may have been something in weewx-benchmark-master/public_html. Go back and do step 3 again.
Add your results to the wiki page Benchmarks of file and image generation