Re: [rust-dev] Debugging rust for a newbie
Hey Huon,
thanks for the help. The problem is really obvious now that you mention it!
Thanks for the debugging tips however. Coming from Ruby all I ever use are
print statements. So it's good to know how to do it!
Urban
On Wed, Jul 23, 2014 at 10:02 AM, Huon Wilson wrote:
> It is unlikely to be a lifetimes thing; far, far more likely to be a
> "normal" infinite recursion. The size of the stack frame of each function
> is fixed at compile time, so the way to blow the stack is by calling a lot
> of functions deeply, e.g. it's not possible to write a loop that places
> more and more objects on the stack (not in safe code, anyway).
>
> You can get a backtrace by running the test in a conventional debugger,
> e.g. `gdb --args ./tester produces_a_move`, then type `run`. When it hits
> the abort, gdb will freeze execution and you can run `backtrace` to see the
> function call stack, to see what is recursing deeply.
>
> You can make rustc emit debug info which makes gdb far more useful, by
> compiling with `-g` or, equivalently, `--debuginfo=2`. (Depending on your
> platform, 'lldb' may be better.)
>
>
> If all else fails, you can fall back to println debugging, e.g.
>
> fn gen_move(&self, ...) -> Move {
> println!("calling gen_move");
>
> // ...
> }
>
> ---
>
> Just glancing over your code, it looks like there's mutual recursion
> between Playout::run and McEngine::gen_move:
>
> - McEngine::gen_move calls Playout::run
> https://github.com/ujh/iomrascalai/blob/88e09fdd/src/engine/mc/mod.rs#L82
> - Playout::run calls Playout::gen_move
> https://github.com/ujh/iomrascalai/blob/88e09fdd/src/playout/mod.rs#L42
> - Playout::gen_move calls McEngine::gen_move
> https://github.com/ujh/iomrascalai/blob/88e09fdd/src/playout/mod.rs#L49
>
>
> Huon
>
>
>
> On 23/07/14 17:42, Urban Hafner wrote:
>
> Hey there,
>
> I'm still quite new to Rust. Until now I was able to fix all my bugs by
> writing tests and/or randomly adding lifetime parameters to keep the
> compiler happy. Now I've hit my first stack overflow. I assume it's due to
> the fact that I've screwed up the lifetimes and the objects live too long
> although I'm not even sure about that. Now my question is: How do I debug
> this? Is there a way to figure out how long objects live? Or how would one
> go about debugging this?
>
> Oh, if you're interested in the failing code:
> https://github.com/ujh/iomrascalai/pull/46
>
> Cheers,
>
> Urban
> --
> Freelancer
>
> Available for hire for Ruby, Ruby on Rails, and JavaScript projects
>
> More at http://urbanhafner.com
>
>
> ___
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Re: [rust-dev] Debugging rust for a newbie
It is unlikely to be a lifetimes thing; far, far more likely to be a
"normal" infinite recursion. The size of the stack frame of each
function is fixed at compile time, so the way to blow the stack is by
calling a lot of functions deeply, e.g. it's not possible to write a
loop that places more and more objects on the stack (not in safe code,
anyway).
You can get a backtrace by running the test in a conventional debugger,
e.g. `gdb --args ./tester produces_a_move`, then type `run`. When it
hits the abort, gdb will freeze execution and you can run `backtrace` to
see the function call stack, to see what is recursing deeply.
You can make rustc emit debug info which makes gdb far more useful, by
compiling with `-g` or, equivalently, `--debuginfo=2`. (Depending on
your platform, 'lldb' may be better.)
If all else fails, you can fall back to println debugging, e.g.
fn gen_move(&self, ...) -> Move {
println!("calling gen_move");
// ...
}
---
Just glancing over your code, it looks like there's mutual recursion
between Playout::run and McEngine::gen_move:
- McEngine::gen_move calls Playout::run
https://github.com/ujh/iomrascalai/blob/88e09fdd/src/engine/mc/mod.rs#L82
- Playout::run calls Playout::gen_move
https://github.com/ujh/iomrascalai/blob/88e09fdd/src/playout/mod.rs#L42
- Playout::gen_move calls McEngine::gen_move
https://github.com/ujh/iomrascalai/blob/88e09fdd/src/playout/mod.rs#L49
Huon
On 23/07/14 17:42, Urban Hafner wrote:
Hey there,
I'm still quite new to Rust. Until now I was able to fix all my bugs
by writing tests and/or randomly adding lifetime parameters to keep
the compiler happy. Now I've hit my first stack overflow. I assume
it's due to the fact that I've screwed up the lifetimes and the
objects live too long although I'm not even sure about that. Now my
question is: How do I debug this? Is there a way to figure out how
long objects live? Or how would one go about debugging this?
Oh, if you're interested in the failing code:
https://github.com/ujh/iomrascalai/pull/46
Cheers,
Urban
--
Freelancer
Available for hire for Ruby, Ruby on Rails, and JavaScript projects
More at http://urbanhafner.com
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[rust-dev] Debugging rust for a newbie
Hey there, I'm still quite new to Rust. Until now I was able to fix all my bugs by writing tests and/or randomly adding lifetime parameters to keep the compiler happy. Now I've hit my first stack overflow. I assume it's due to the fact that I've screwed up the lifetimes and the objects live too long although I'm not even sure about that. Now my question is: How do I debug this? Is there a way to figure out how long objects live? Or how would one go about debugging this? Oh, if you're interested in the failing code: https://github.com/ujh/iomrascalai/pull/46 Cheers, Urban -- Freelancer Available for hire for Ruby, Ruby on Rails, and JavaScript projects More at http://urbanhafner.com ___ Rust-dev mailing list Rust-dev@mozilla.org https://mail.mozilla.org/listinfo/rust-dev
