Lua Debugger that can Attach to Process

Question

My company has a program that uses Lua embedded in its runtime, loading up .lua files from disk and executing functions defined in them repeatedly.

Is there a way to attach to the running process and set breakpoints in my .lua files? (I'd accept either gdb-style command-line debugging as part of the Lua distribution, or perhaps a third-party IDE that provides Visual-Studio-like GUI breakpoints.)

Or is what I'm asking for entirely nonsensical and impossible given the nature of the runtime loading up random files from disk?

Edit: Looks like it's not nonsensical, given that Lua's own debug.getinfo() function can determine the source file for a given function, and debug.sethook() allows a callback for each new line of code entered. So, it's reasonable to load source code from disk and be able to tell when the interpreter is executing a particular line of code from that file. The question remains: how do I latch onto an existing process that has a Lua interpreter and inject my own trace function (which can then watch for file/line number pairs and pause execution)?

Answer 1

If you can modify the .lua files, you can insert the following call just before anything you need to debug:

require 'remdebug.engine'.start()

It starts the RemDebug Lua debugger engine and tries to connect to a controller. If it cannot connect, it will just continue running as normal. I did some fixes to the debugger engine, such as dealing with temporary variables, and my student is working on a debugger GUI (due next year).

In the meantime, you can try if Lua Development Tools works for you. It features a debugger similar to RemDebug, which should be possible to set up as follows:

require("debugger")(host, port, idekey)

Alternatively, you can use SciTE-debug, which is an extension to the SciTE editor, and can serve as a controller to RemDebug. Just make sure you insert the call to remdebug.engine.start somewhere in your Lua code and insert this into the SciTE output window:

:debug.target=remote.lua

When you start your program, SciTE should show the source and current line.

Answer 2

I've been using Decoda editor for that. It allows you to attach to a running C++ application, after that it detects that you're running a Lua Interpreter within your C++ code and show your Lua source code, where you can add beakpoints and inspect variables as usual.

Answer 3

This is an alternative I use after much searching. If you have an external executable that loads lua, I got this working in a few minutes. The op is very responsive, it has an interactive debugger which loads your code you can place debug points interactively. It doesn't have an editor, but I use scite or crimson editor and start the executable, one line in your main lua module enables the debugger.

http://www.cushy-code.com/grld/ - this link seems dead now

I've moved to eclipse.org/ldt it has an ide and integrated debugger, recommended

hth

Answer 4

The Lua plugin for IntelliJ has a working debugger with no special setup required other than pointing to your Lua interpreter.

Here's a screencast of it:

http://www.screencast.com/t/CBWIkoZPg

Answer 5

Similar to what Michal Kottman described, I have implemented a debugger based on RemDebug, but with additional fixes and features (on github: https://github.com/pkulchenko/MobDebug).

You can update your .lua file with require("mobdebug").start("localhost", 8171) at the point where you want the debugging to start. You can then use the command line debugger to execute commands, set breakpoints, evaluate/execute expressions and so on.

As an alternative, you can use ZeroBrane Studio IDE, which integrates with the debugger and gives you a front-end to load your code and execute same debugger commands in a nice GUI. If you want to see the IDE in action, I have a simple demo here: http://notebook.kulchenko.com/zerobrane/live-coding-in-lua-bret-victor-style.

Answer 6

You should probably use Decoda.
Go to Debug -> Processes -> Attach to attach your process. This should work fine.

Answer 7

Well the easiest way is this, thanks to the genius author https://github.com/slembcke/debugger.lua

you don't need to setup a remote debug server ,just require one file,and simplely call dbg() and it will pause,just like gdb

an tutorial is also shipped with it, check it out.