Why does Valgrind not detect a memory leak in a Rust program using nightly 1.29.0?

by

Rust 1.32

As of Rust 1.32, the default allocator for an executable is now the system allocator, so you don’t need to set anything by default.

Previous versions

You aren’t using the global allocator setting correctly. This is a nightly feature, which means that it’s prone to change at any time. Your blog post is out of date.

Check the module docs for std::alloc to see the correct usage:

#![feature(alloc_system)]
extern crate alloc_system;

#[global_allocator]
static GLOBAL: alloc_system::System = alloc_system::System;

use std::mem;

fn allocate() {
    let bad_vec = vec![0u8; 1024*1024];
    mem::forget(bad_vec);
}

fn main() {
    allocate();
}

root@3fb431791293:/tmp/vg# valgrind target/debug/vg
==6326== Memcheck, a memory error detector
==6326== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==6326== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==6326== Command: target/debug/vg
==6326==
==6326==
==6326== HEAP SUMMARY:
==6326==     in use at exit: 1,048,576 bytes in 1 blocks
==6326==   total heap usage: 12 allocs, 11 frees, 1,050,753 bytes allocated
==6326==
==6326== LEAK SUMMARY:
==6326==    definitely lost: 1,048,576 bytes in 1 blocks
==6326==    indirectly lost: 0 bytes in 0 blocks
==6326==      possibly lost: 0 bytes in 0 blocks
==6326==    still reachable: 0 bytes in 0 blocks
==6326==         suppressed: 0 bytes in 0 blocks
==6326== Rerun with --leak-check=full to see details of leaked memory
==6326==
==6326== For counts of detected and suppressed errors, rerun with: -v
==6326== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

More Related Contents:

  1. Traits and Rust
  2. Why do try!() and ? not compile when used in a function that doesn’t return Option or Result?
  3. Why do I need to import a trait to use the methods it defines for a type?
  4. Should trait bounds be duplicated in struct and impl?
  5. How do I collect into an array?
  6. Can I do type introspection with trait objects and then downcast it?
  7. Cannot borrow as mutable more than once at a time in one code – but can in another very similar
  8. How can I perform parallel asynchronous HTTP GET requests with reqwest?
  9. Is it considered a bad practice to implement Deref for newtypes?
  10. Implementing a trait for multiple types at once
  11. Convert a String to int?
  12. How do I get an owned value out of a `Box`?
  13. How do I borrow a RefCell, find a key, and return a reference to the result? [duplicate]
  14. Converting from Option to Option
  15. What is the difference between `e1` and `&e2` when used as the for-loop variable?
  16. Why doesn’t println! work in Rust unit tests?
  17. How do you use parent module imports in Rust?
  18. What does ‘let x = x’ do in Rust?
  19. How can I call a raw address from Rust?
  20. Is there a way to perform an index access to an instance of a struct?
  21. How to take ownership of T from Arc?
  22. Is there any trait that specifies numeric functionality?
  23. How to use a local unpublished crate?
  24. Why do I get “type annotations needed” when using Iterator::collect?
  25. Why can I iterate over a slice twice, but not a vector?
  26. When is it necessary to circumvent Rust’s borrow checker?
  27. How to idiomatically alias a crate in Rust 2018?
  28. Why do I get “does not live long enough” in a return value?
  29. How do I cope with lazy iterators?
  30. Can a struct containing a raw pointer implement Send and be FFI safe?

Leave a Comment