Ddtrace

This patch release includes 2 fixes:

- Fix span/trace id generation collisions when forking by reverting the changes we made to speed up id generation. (1470)

- Force rebuilding of Cython files in setup.py. This will ensure that we build for the right Python
version. (1468)
---

Integrations

Celery
- Support for distributed tracing was added in 1194. It is default disabled but is easily enabled via `DD_CELERY_DISTRIBUTED_TRACING=true` or via the config API `ddtrace.config.celery['distributed_tracing'] = True`. Thanks thieman!
- Analyzed span configuration was added to easily configure Celery spans to be analyzed. This can be done via the environment variable `DD_CELERY_ANALYTICS_ENABLED=true` or with the config API `ddtrace.config.celery['analytics_enabled'] = True`.

Django
- A config option was added to allow enabling/disabling instrumenting middleware. It can be set with the environment variable `DD_DJANGO_INSTRUMENT_MIDDLEWARE=true|false` or via the config API `ddtrace.config.django['instrument_middleware'] = False default is True`.


Core
- Runtime ID tag support for traces and profiles. This will allow us to correlate traces and profiles generated by applications.

OpenTracing
- Support for `active_span()` was added to our OpenTracing tracer.

Profiling
- Storing of span id in profiling events which will enable linking between a trace and a profile in the product.

Tracer
- `DD_TAGS` environment variable added to replace `DD_TRACE_GLOBAL_TAGS`.


Changes

New features
- opentracer: implement active_span (1395)
- django: add config for instrumenting middleware (1384)
- celery: Add analyzed span configuration option (1383)
- Add runtime id tag support for traces & profiles (1379)
- profiling: retry on upload error (1376)
- tracer: Add DD_TAGS environment variable support (1315)
- celery: Add distributed tracing (1194 -- thanks thieman)
- profiling: Store span ids in profiling events (1043)


Improvements
- monkey: add better error messages (1430)
- Make hooks settings generic (1428)
- internal: Change trace too large message to debug (1403 -- thanks ZStriker19)
- internal: Ensure queue is at or over max size before dropping (1399)
- performance: improve span id generation (1378)


Bug fixes
- hooks: use log.error to log hook exceptions (1436)
- writer: raise RuntimeError("threads can only be started once") (1425 -- thanks YasuoSasaki)
- settings: pass the `memodict` argument to subcall to deepcopy (1401)
- profiling: correct the scheduler sleep time based on exporter time (1386)
- integration config: copy and deepcopy implementations (1381)
- utils: do not expose deepmerge function (1375)


Documentation
- Updated to pypi advance usage docs (1402)


Testing
- update tests to latest versions of libraries (1434, 1433, 1432, 1424, 1423, 1422, 1421, 1420, 1419, 1418, 1417, 1416, 1412, 1411, 1410, 1409, 1408, 1407, 1406, 1405)
- circleci: remove unused busybox (1426)

---

- Fix for an issue introduced by patching classes in the MRO of a Django View class (1625).

---

- reintroduce wrapt for patching Django view methods. ([1622](https://github.com/DataDog/dd-trace-py/pull/1622))


---

This patch release includes fixes for install problems with Alpine Linux as well as for a bug with tag encoding in the profiler.

Fixes

- fix(profiling/http): make sure tags are UTF-8 encoded (1393)
- fix(profiling): allow to build on Alpine Linux (1391)
- fix: don't allow package version to be `None` (1380)
---

This release introduces mainly bug fixes as well as some new configuration options for the profiling library.

Profiler
New environment variables have been added to allow you to easily configure and describe your application in Datadog.

- `DD_SITE`: Specify which site to use for uploading profiles. Set to ``datadoghq.eu`` to use EU site.
- `DD_API_KEY`: an alias to `DD_PROFILING_API_KEY`.
- `DD_ENV`: the environment in which your application is running. eg: prod, staging
- `DD_VERSION`: the version of your application. eg: 1.2.3, 6c44da20, 2020.02.13
- `DD_SERVICE`: the service which your application represents.


Changes

Bug fixes
- tracer: stop previous writer if a new one is created (1356)
- Fix task context management for asyncio in Python <3.7 (1353)
- fix(profiling): pthread_t is defined as unsigned long, not int (1347)
- span: handle non-string tag keys (1345)
- fix(profiling): use formats.asbool to convert bool from env (1342)
- fix: avoid context deadlock with logs injection enabled (1338 -- thanks zhammer)
- fix: make C extensions mandatory (1333)
- fix(profiling): allow to override options after load (1332)
- fix(profiling): ignore failure on shutdown (1327)
- logging: fix docs typo (1323)

Integrations

- Add config to omit `django.user.name` tag from request root span (1361 -- thanks sebcoetzee)
- Update error event handler name within SQLAlchemy engine (1324 -- thanks RobertTownley)
- docs(opentracing): add celery example (1329)


Core

- refactor(tracer): remove property for Tracer.context_provider (1371)
- writer: allow configuration of queue maxsize via env var (1364)
- feat(profiling): replace http_client by urllib for uploading (1359)
- feat(profiling): allow to pass service_name to HTTP exporter (1358)
- Updates configuration docs (1360 -- thanks sburns)
- feat(profiling): add the pip install when recompilation is needed (1334)
- tracer: support tracing across `fork()` (1331)
- Allow Profiler to finish upload data in the background when stopped (1322)


Tests
- test(profiling): check for thread presence rather than number of threads (1357)
- aiobotocore: pin to <1.0 (1330)
- ci: allow to use latest pytest version (1326)
- fix(tests/profiling): use a string with setenv, not an int (1321)

---