|+ **Support `Redis`, `PDO`, `MySQLi`**, use `Swoole\Runtime::enableCoroutine()` to make them become Async IO by coroutine scheduler
+ **Coroutine tracking**: `Coroutine::listCoroutines()` can list all current coroutines, `Coroutine::getBackTrace($cid)` gets the function call stack of a coroutine
+ Refactoring `Co\Channel` C code to C++, solving unintended consequences of complex scenes and achieving high stability
+ Refactoring `Co\Http\Client` C code to C++ coroutine mode, solving asynchronous timing problems and achieving high stability
+ Support for using `exit` in coroutines and Servers, which will throw a catchable `\Swoole\ExitException` exception.
+ Remove PCRE dependency limits for all iterators (table/connection/coroutine_list)
+ Add the `open_websocket_close_frame` configuration to receive close frames in the onMessage event
+ Remove the `Http\Response->gzip()` method and use the `http_compression` configuration item instead. The bottom layer will automatically determine the client's incoming `Accept-Encoding` to select the appropriate compression method, add Google BR compression support
+ Add `Co\Http\Client->addData()` method to send the data in the memory as the content of the uploaded file.
+ `Solaris` system support
+ Http2 supports `MAX_FRAME_SIZE` framing transmission and `MAX_HEADER_LIST_SIZE` processing. The client adds `isStreamExist` method to detect whether there is a corresponding stream.
+ `swoole_http_response->status` increases the `reason` parameter
* Fixed an issue where unsigned arguments in MySQL prepare used signed values ??to cause numeric overflows
* Fixed an issue with no coroutine in the `onRequest` callback for HTTP2
* Fixed the problem that `tasking_num` became `-1` in some special cases
* Fixed HTTP2-server window-update frame construction error
* Fix all levels of compile warning under all PHP versions
* Compile error will occur when GCC version is less than 4.8
* Fixed MySQL's memory allocation caused by the use of prepare statement without parameter binding
* Fixed old stream memory loss leak when HTTP2 client reconnect
* Fixed wrong package info by version 4.1.0