Valgrind没有显示任何分配

Question

我正在学习Rust而且我正在玩Box,所以我尝试检查泄漏,valgrind但它表明堆上没有分配:

$ rustc -C opt-level=0 raii.rs
$ valgrind ./raii
==3850== Memcheck, a memory error detector
==3850== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==3850== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==3850== Command: ./raii
==3850== 
5
Changed:10
==3850== 
==3850== HEAP SUMMARY:
==3850==     in use at exit: 0 bytes in 0 blocks
==3850==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==3850== 
==3850== All heap blocks were freed -- no leaks are possible
==3850== 
==3850== For counts of detected and suppressed errors, rerun with: -v
==3850== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

valgrind --leak-check=full ./raii 显示exaclty相同的结果.

这是Rust代码:

fn main() {
    let mut _box2 = Box::new(5i32);

    println!("{}", _box2);
    *_box2 = 10i32;
    println!("Changed:{}", _box2);

    {
        let _box3 = Box::new(4i32);
    }
}

其他一些信息:

$ rustc -V
rustc 1.8.0 (db2939409 2016-04-11)

$ valgrind --version
valgrind-3.10.1

$ uname -a
Linux 3.19.0-59-generic #65~14.04.1-Ubuntu SMP Tue Apr 19 18:57:09 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

这是为什么？我以为Box在堆上分配变量.此外,此示例显示几乎相同的代码,valgrind显示那里的分配.

如果我添加以下代码:

let _stack = (1u64, 2u64, 3u64);
let _heap = Box::new((4u64, 5u64, 6u64));
println!("Memory used by stack: {} bytes", std::mem::size_of_val(&_stack));
println!("Memory used by heap: {} bytes", std::mem::size_of_val(&_heap));

它打印完全符合预期:

$ ./raii 
Memory used by stack: 24 bytes
Memory used by heap: 8 bytes

- 在第二种情况下,元组被放置在堆上,指针(8个字节)被推入堆栈,而在第一种情况下,元组被放置在堆栈上,因此需要24个字节.

Valgrind似乎能够计算其他程序的堆分配:

$ valgrind echo "test"
==4575== Memcheck, a memory error detector
==4575== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==4575== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==4575== Command: echo test
==4575== 
test
==4575== 
==4575== HEAP SUMMARY:
==4575==     in use at exit: 0 bytes in 0 blocks
==4575==   total heap usage: 30 allocs, 30 frees, 3,681 bytes allocated
==4575== 
==4575== All heap blocks were freed -- no leaks are possible
==4575== 
==4575== For counts of detected and suppressed errors, rerun with: -v
==4575== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Answer 1

在构建二进制文件时,Rust使用jemalloc作为分配器.目前编译jemalloc的方式不包含所需的valgrind挂钩.

如果您需要能够使用valgrind跟踪分配,那么如果您每晚使用Rust ,则可以切换到系统分配器:

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