Simon Willison’s Weblog

lemongraph. An open-source “log-based transactional graph engine”. Written by the NSA. In Python. It runs on top of LMDB, which is the fast memory-mapped transactional key-value store that was developed by the OpenLDAP project as a replacement for BerkeleyDB.

# 9:15 pm / graph, open-source, nsa

The Four Golden Signals. “The four golden signals of monitoring are latency, traffic, errors, and saturation. If you can only measure four metrics of your user-facing system, focus on these four.”—from the excellent (and free) Google Site Reliability Engineering book.

# 9:23 pm / monitoring