Recommended debugging techniques

[czechboy0]

I was wondering how you approach debugging Curassow (with lldb), since it forks off worker processes at the beginning and lldb doesn't support automatic following of forks.

I found a very tedious way:

• run your server in terminal window 1
• in another window launch lldb for your binary
• run attach WORKER_PID, which is visible when the server starts
• continue as usual in the lldb instance, allowing to inspect the incoming requests in the debugger

This will obviously get untenable as a codebase grows, so I'm wondering what your thoughts on this are.

[kylef]

I try to limit debugging via Curassow, I'd usually try and write a test that has the same behaviour and attach lldb to the test runner.

As for problems in your application, you can just hit the Nest callback directly, I was planning to write some convenience testing functions to make that easier.

[czechboy0]

If you could just add two lines on how one can do that in the readme I'd consider that enough for what I was going for here :)

[kylef]

You can use make run-tests to build the test runner, which can be run with ./run-tests. So to attach that to lldb:

$ make run-tests
$ lldb ./run-tests
< add all your breakpoints etc here>
(lldb) r
Process 50884 launched: './run-tests' (x86_64)
-> HTTPParser
  -> can parse a HTTP request body
  -> reads the message body when Content-Length is present
  -> throws an error when the client uses bad HTTP syntax
  -> throws an error when the client uses a bad HTTP version
  -> throws an error when the client disconnects before sending an HTTP request
  -> throws an error when the client disconnects before sending the entire message body

6 passes and 0 failures
Process 50884 exited with status = 0 (0x00000000) 

[czechboy0]

Yeah that's pretty much what I'm doing, thanks!

[kylef]

Are you trying to debug an issue with Curassow specifically or your application? If there is a bug with Curassow please open an issue and I can take a look. If it's with your application, I'd suggest removing Curassow from the mix completely and testing your application directly [example].

[czechboy0]

No bug in Currasow, I was just debugging my server running on it. Ok thanks