Ddtrace

This release includes performance improvements in the core library, updates profiling, and configuration changes to several integrations. This release also adds support for installing on Windows.

grpc

* Use `ddtrace.config.grpc["service_name"]` to set service name reported by default for gRPC client instances. The ``DD_GRPC_SERVICE`` environment variable can also be used.

redis

* Use `ddtrace.config.redis["service"]` to set the service name for the `redis` integration. The environment variable `DD_REDIS_SERVICE` can also be used.

httplib

* To enable distributed tracing, use `ddtrace.config.httplib["distributed_tracing"]`. By default, distributed tracing for `httplib` is disabled.

Changes

Improvements

- fix(monkey): use lock on manual patched module add (1479 -- thanks uniq10)
- core: re-enable custom rng (1474)
- core: rewrite queue (1534)
- pin: make service optional (1529)
- feat(ddtrace-run): allow to enable profiling (1537)
- feat(profiling): enable flush on exit by default for Profiler (1524)
- fix(grpc): compute service name dynamically (1530)
- feat(redis): add global service configuration (1515)
- feat(httplib): support distributed tracing (1522 -- thanks jirikuncar)
- refactor(profiling): hide Profiler._schedulers (1523)
- feat(profiling): set Datadog-Container-Id when uploading profiles (1520)
- feat(profiling/http): emit log message when server returns 400 (1477)
- feat(profiling): validate API key format (1459)

Bug fixes

- fix(profiling): fix memory leak in Python 2 stack collector (1568)
- fix(profiling): disable exception profiling on Windows (1538)
- fix(profiling/stack): fix GIL switching (1475)

Full changeset

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.39.0...v0.40.0).

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

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

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Deprecations

- The `decode()` method on our encoders located in `ddtrace.encoders` is scheduled to be removed in 0.40.

Integrations

Django

- Add headers tracing configuration. This will enable headers on requests to be attached as tags on request spans. This can be done by using the `ddtrace.config` API like so: `config.django.http.trace_headers(["my-header-i-want-to-trace"])`. Thanks to JoseKilo for contributing this feature!
- Fix for a bug where we didn't handle all cases for a template name. Thanks sibsibsib!

Elasticsearch

- Fix for a bug that causes the tracer to crash if params is `None`.

grpc

- Fix handling `None` RpcMethodHandlers

Tracer

- core: deprecate encoder decode()

Profiling

- Now included by default with the tracing package
- Support for the `DD_ENV` and `DD_VERSION` environment variable configuration.
- A bunch of gevent fixes. See below for the details.

OpenTracing

- Support for tracer interleaving between the Datadog tracer (used in integrations) and the OpenTracing tracer provided in the library.


Full Change set

Deprecations

- core: deprecate encoder decode() (1496)

Features

- docs: add changelog from github (1503)
- feat(profiling): disable trace tracking in tracer by default (1488)
- feat(profiling): allow to pass version to Profiler (1478)
- feat(profiling): allow to pass env to Profiler (1473)
- feat(profiling): install the profiling extra by default (1463)
- feat(profiling): raise an error on start if endpoint is empty (1460)
- feat(profiling): validate API key format (1459)
- feat(profiling): track gevent greenlets (1456)
- feat(profiling/pprof): export trace id as stack labels (1454)
- feat(django): Implement headers tracing (1443 -- thanks JoseKilo)
- feat(profiling): allow to pass service_name to the Profiler object (1440)
- feat(opentracing): support for tracer interleaving (1394)

Fixes

- fix(profiling): multi-threading/gevent issues with ThreadLinkSpan (1485)
- refactor(profiling/recorder): remove filtering mechanism (1482)
- fix(profiling/stack): lock _WeakSet in ThreadSpanLinks (1469)
- span: changed finished attribute implementation (1467)
- fix(grpc): RpcMethodHandler can be None (1465)
- fix(elasticsearch): ensure params is a dict before urlencoding (1449, 1451)
- fix(profiling): identify Python main thread properly with gevent (1445)
- fix(django) handle different template view name types (1441 -- thanks sibsibsib)
- fix(profiling/periodic): make sure that a service cannot be started twice (1439)
- fix(profiling): use gevent.monkey rather than private _threading module (1438)
- fix(profiling): fix negative CPU time (1437)
- fix(profiling/periodic): PERIODIC_THREAD_IDS race condition (1435)

Tests

- test: show 10 slowest tests (1504)
- test(profiling): fix stress test (1500)
- test(profiling): fix test_truncate random failure (1498)
- test(profiling): fix test_collect_once random failure (1497)
- test(profiling/http): fix fail cases (1493)
- test(profiling): enable verbose + no capture (1490)
- test(profiling): increase error tolerance (1489)
- test(profiling): make stack stress test gevent compatible (1486)
- tests: wait for uds server to start before using it (1472)
- ci: update Python versions (1446)

https://github.com/DataDog/dd-trace-py/compare/v0.38.2...v0.39.0

https://github.com/DataDog/dd-trace-py/milestone/57?closed=1

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

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