de6ed9ba9f
- Switched from yapf to black - Reconfigure isort for black - Resolve black/pylint idiosyncrasies Note: I used `--experimental-string-processing` because black was producing "implicit string concatenation", similar to what described here: https://github.com/psf/black/issues/1837. While currently this feature is experimental, it will be enabled by default: https://github.com/psf/black/issues/2188. After running black with the new string processing so that the generated code merges these `"hello" " world"` strings concatenations, then I removed `--experimental-string-processing` for stability, and regenerated the code again. To the reviewer: don't even try to open "Files Changed" tab 😄 It's better to review commit-by-commit, and ignore `run black and isort`.
gRPC Python Debug Example
This example demonstrate the usage of Channelz. For a better looking website, the gdebug uses gRPC-Web protocol and will serve all useful information in web pages.
Channelz: Live Channel Tracing
Channelz is a channel tracing feature. It will track statistics like how many messages have been sent, how many of them failed, what are the connected sockets. Since it is implemented in C-Core and has low-overhead, it is recommended to turn on for production services. See Channelz design doc.
How to enable tracing log
The tracing log generation might have larger overhead, especially when you try to trace transport. It would result in replicating the traffic loads. However, it is still the most powerful tool when you need to dive in.
The Most Verbose Tracing Log
Specify environment variables, then run your application:
GRPC_VERBOSITY=debug
GRPC_TRACE=all
For more granularity, please see environment_variables.
Debug Transport Protocol
GRPC_VERBOSITY=debug
GRPC_TRACE=tcp,http,secure_endpoint,transport_security
Debug Connection Behavior
GRPC_VERBOSITY=debug
GRPC_TRACE=call_error,connectivity_state,pick_first,round_robin,glb
How to debug your application?
pdb is a debugging tool that is available for Python interpreters natively.
You can set breakpoint, and execute commands while the application is stopped.
The simplest usage is add a single line in the place you want to inspect:
import pdb; pdb.set_trace(). When interpreter see this line, it would pop out
a interactive command line interface for you to inspect the application state.
For more detailed usage, see https://docs.python.org/3/library/pdb.html.
Caveat: gRPC Python uses C-Extension under-the-hood, so pdb may not be
able to trace through the whole stack.
gRPC Command Line Tool
grpc_cli is a handy tool to interact with gRPC backend easily. Imageine you can
inspect what service does a server provide without writing any code, and make
gRPC calls just like curl.
The installation guide: https://github.com/grpc/grpc/blob/master/doc/command_line_tool.md#code-location The usage guide: https://github.com/grpc/grpc/blob/master/doc/command_line_tool.md#usage The source code: https://github.com/grpc/grpc/blob/master/test/cpp/util/grpc_cli.cc