v0.47.0

Upgrade Notes

The profiler now automatically sets up uWSGI compatibility in auto mode or with profile_children=True. Make sure that you don't have custom code instrumenting the profiler in those cases.
The Tracer class properties DEFAULT_HOSTNAME, DEFAULT_PORT, DEFAULT_DOGSTATSD_PORT, DEFAULT_DOGSTATSD_URL, DEFAULT_AGENT_URL have been removed.
elasticsearch: removed get_traced_transport method and ddtrace.contrib.elasticsearch.transport module.

cherrypy: introduce TraceMiddleware for the CherryPy web framework.
django: tag root spans as measured.
elasticsearch: add support for version 7.
fastapi: add integration.
Introduce support for the DD_SERVICE_MAPPING environment variable to allow remapping service names on emitted spans.
httplib: distributed tracing is now enabled by default.
The profiler now supports most operation mode from uWSGI without much configuration. It will automatically plug itself in post fork hooks when multiprocess mode is used.
wsgi: add tracing middleware.

Resolves an issue in Django tracing where, if query_string is not present in request.META, a KeyError is raised, causing the request to 500
Deprecate the DD_LOGGING_RATE_LIMIT variable in favor of the standard DD_TRACE_LOGGING_RATE for configuring the logging rate limit.
sampler: removed bug causing sample_rate of 0 to be reset to 1, and raise ValueError instead of logging.
starlette: unpatch calls correctly.
flask: fix memory leak of sampled out traces.
Fix CPU time and wall time profiling not ignoring the profiler tasks with gevent.

The default maximum CPU time used for the stack profiler (CPU time, wall time and exceptions profiling) has been decreased from 2% to 1%.