为什么Valgrind在夜间使用1.29.0时没有检测到Rust程序中的内存泄漏？

Question

我正在尝试使用Valgrind在此博客文章后检测Rust程序中的内存泄漏.我的源代码很简单:

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

use std::mem;

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

fn main() {
    allocate();
}

我希望调用mem::forget()生成一个Valgrind可以接收的内存泄漏.但是,当我运行Valgrind时,它报告没有泄漏是可能的:

[memtest]> cargo run
   Compiling memtest v0.1.0 (file:///home/icarruthers/memtest)
    Finished dev [unoptimized + debuginfo] target(s) in 0.28s
     Running `target/debug/memtest`
[memtest]> valgrind target/debug/memtest
==18808== Memcheck, a memory error detector
==18808== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==18808== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==18808== Command: target/debug/memtest
==18808== 
==18808== 
==18808== HEAP SUMMARY:
==18808==     in use at exit: 0 bytes in 0 blocks
==18808==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==18808== 
==18808== All heap blocks were freed -- no leaks are possible
==18808== 
==18808== For counts of detected and suppressed errors, rerun with: -v
==18808== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

我升级到最晚每晚(1.29.0-夜间(6a1c0637c 2018-07-23)).

我错过了什么？

Answer 1

Rust 1.32

从Rust 1.32开始,可执行文件的默认分配器现在是系统分配器,因此默认情况下不需要设置任何内容.

之前的版本

您没有正确使用全局分配器设置.这是一个夜间功能,这意味着它随时都可能发生变化.您的博客文章已过期.

检查模块文档std::alloc以查看正确的用法:

#![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)