Ddtrace

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

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Changes

- feat: add asgi integration (1567)
- feat(profiling): reduce the default amount of sampling for memory/lock to 2% (1586)
- fix(profiling/line2def): handle empty filename (1585)
- fix(grpc): GRPC Channel Pin (1582 -- thanks munagekar)
- feat(core): make environment variables consistent with other languages (1575)
- fix(profiling,gevent): fix race condition with periodic thread (1569)
- fix(core): disable import hooks (1563)
- feat(core): set tags from DD_TAGS (1561)
- fix(profiling): lock Recorder on reset (1560)
- feat(django): add option for using legacy resource format (1551 -- thanks tredzko, jheld)
- feat(core): add startup logging (1548)
- feat(core): add msgpack encoder (1491)

Full changeset

https://github.com/DataDog/dd-trace-py/compare/v0.40.0...v0.41.0


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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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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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