leak-detect-allocator

Idea

It's hard to detect memory leak, with a global allocator, we can trace the alloc add dealloc, if we record the call stacks of alloc operation, then we can see where the code lead memory leak. This tool do NOT record ALL allocation, but delete the record when dealloc.

Powerd by global allocator + heapless + backtrace, it's only support nightly toolchain, caused by new_uninit and const_fn features.

Usage

Add this to your cargo.toml:

leak-detect-allocator = {git = "https://github.com/lynnux/leak-detect-allocator.git"}

Example:

#[global_allocator]
static LEAK_TRACER: LeakTracerDefault = LeakTracerDefault::new();

#[tokio::main]
async fn main() -> Result<(), BoxError> {
    let lda_size = LEAK_TRACER.init();
    tokio::spawn(async move {
        loop {
            tokio::signal::ctrl_c().await.ok();
            let mut out = String::new();
            let mut count = 0;
            let mut count_size = 0;
            LEAK_TRACER.now_leaks(|addr, frames| {
                count += 1;
                let mut it = frames.iter();
                // first is the alloc size
                let size = it.next().unwrap_or(&0);
                if *size == lda_size {
                    return true;
                }
                count_size += size;
                out += &format!("leak memory address: {:#x}, size: {}\r\n", addr, size);
                for f in it {
                    // Resolve this instruction pointer to a symbol name
                    unsafe {
                        out += &format!(
                            "\t{}\r\n",
                            LEAK_TRACER.get_symbol_name(*f).unwrap_or("".to_owned())
                        );
                    }
                }
                true // continue until end
            });
            out += &format!("\r\ntotal address:{}, bytes:{}, internal use for leak-detect-allacator:{} bytes\r\n", count, count_size, lda_size*2);
            std::fs::write("foo.txt", out.as_str().as_bytes()).ok();
        }
    });
}

When CTRL+C, it will get a "foo.txt", and the output is like:

leak memory address: 0x44e440, size: 10
	backtrace::backtrace::trace_unsynchronized<closure-0>
	leak_detect_allocator::{{impl}}::alloc<leak_detect_allocator::LeakData<typenum::uint::UInt<typenum::uint::UInt<typenum::uint::UInt<typenum::uint::UInt<typenum::uint::UTerm, typenum::bit::B1>, typenum::bit::B0>, typenum::bit::B1>, typenum::bit::B0>>,typenu
	flashcore::_::__rg_alloc
	alloc::alloc::alloc
	alloc::alloc::{{impl}}::alloc
	alloc::raw_vec::RawVec<u8, alloc::alloc::Global>::allocate_in<u8,alloc::alloc::Global>
	alloc::raw_vec::RawVec<u8, alloc::alloc::Global>::with_capacity<u8>
	alloc::vec::Vec<u8>::with_capacity<u8>
	alloc::slice::hack::to_vec<u8>
leak memory address: 0x4508c0, size: 30
	backtrace::backtrace::trace_unsynchronized<closure-0>
	leak_detect_allocator::{{impl}}::alloc<leak_detect_allocator::LeakData<typenum::uint::UInt<typenum::uint::UInt<typenum::uint::UInt<typenum::uint::UInt<typenum::uint::UTerm, typenum::bit::B1>, typenum::bit::B0>, typenum::bit::B1>, typenum::bit::B0>>,typenu
	flashcore::_::__rg_alloc
	alloc::alloc::alloc
	alloc::alloc::{{impl}}::alloc
	alloc::raw_vec::RawVec<u8, alloc::alloc::Global>::allocate_in<u8,alloc::alloc::Global>
	alloc::raw_vec::RawVec<u8, alloc::alloc::Global>::with_capacity<u8>
	alloc::vec::Vec<u8>::with_capacity<u8>
	alloc::slice::hack::to_vec<u8>
	...
total address:38, bytes:6373, internal use for leak-detect-allacator:7077904 bytes	

Stack calls seems better in debug version.

Customize

	// change the vec size to bigger, so we can save more call stack
        use crate::{
            consts, ArrayLength, FnvIndexMap, HeaplessVec, LeakData, LeakDataTrait, LeakTracer,
        };
        let aa = LeakTracer::<LeakData<consts::U20>, _>::new();
        println!("size: {}", aa.init());
		
		
	// change the whole indexmap size, so we get more space to save
	struct CustomData<VN: ArrayLength<usize>> {
            inner: FnvIndexMap<usize, HeaplessVec<usize, VN>, consts::U16384>, // --> U16384 is customized
        }
        impl<VN: ArrayLength<usize>> LeakDataTrait<VN> for CustomData<VN> {
            fn insert(&mut self, key: usize, value: HeaplessVec<usize, VN>) {
                self.inner.insert(key, value).ok();
            }
            fn contains_key(&self, key: usize) -> bool {
                self.inner.contains_key(&key)
            }
            fn remove(&mut self, key: usize) {
                self.inner.remove(&key);
            }
            fn iter_all<F>(&self, mut f: F)
            where
                F: FnMut(usize, &HeaplessVec<usize, VN>) -> bool,
            {
                for (addr, symbol_address) in self.inner.iter() {
                    if !f(*addr, symbol_address) {
                        break;
                    }
                }
            }
        }
        let bb = LeakTracer::<CustomData<consts::U12>, _>::new();
        println!("size: {}", bb.init());

Known Issues

On Win7 64, if you encounter deadlock, you can try place a newer version of dbghelp.dll to your bin directory.