Diamond is a python daemon that collects system metrics and publishes them to Graphite (and others). It is capable of collecting cpu, memory, network, i/o, load and disk metrics. Additionally, it features an API for implementing custom collectors for gathering metrics from almost any source.
I ran a test with the vanilla agent installed on Ubuntu 16.04 on Aug 31st and found that logs are getting rotated, but the original rotated log file is kept open.
It appears TimedRotatingFileHandler is not handling multiple writer threads well. http://thinlight.org/2011/08/10/python-logging-from-multiple-processes/ is an article highlighting the issue.
I ran a test with the vanilla agent installed on Ubuntu 16.04 on Aug 31st and found that logs are getting rotated, but the original rotated log file is kept open.