Heapster

https://docs.rs/heapster/0.9.0/heapster/
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Heapster is a lightweight wrapper that enhances the global allocator in Rust with useful metrics and...
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### Display Heap Statistics and Histograms

Source: https://docs.rs/crate/heapster

Example output generated by the fmt feature, showing allocation counts, averages, and power-of-two size distribution histograms.

```text
alloc_count: 10,949,628
alloc_avg: 2.45 KiB

dealloc_count: 10,949,372
dealloc_avg: 4.09 KiB

realloc_growth_count: 365,968
realloc_growth_avg: 49.12 KiB

realloc_move_count: 351,933
realloc_move_avg: 7.21 KiB

use_curr: 260.39 KiB
use_max: 25.01 MiB

alloc_histogram:
[    4 B ..     8 B):         2  █
[    8 B ..    16 B):   642,064  ███████████
[   16 B ..    32 B):       155  █
[   32 B ..    64 B): 1,639,279  █████████████████████████████
[   64 B ..   128 B): 1,926,643  ██████████████████████████████████
[  128 B ..   256 B): 1,123,746  ████████████████████
[  256 B ..   512 B): 1,284,154  ██████████████████████
[  512 B ..   1 KiB): 2,246,658  ████████████████████████████████████████
[  1 KiB ..   2 KiB): 1,283,935  ██████████████████████
[  2 KiB ..   4 KiB):   160,612  ██
[  4 KiB ..   8 KiB):       411  █
[  8 KiB ..  16 KiB):   320,985  █████
[ 16 KiB ..  32 KiB):         1  █
[ 32 KiB ..  64 KiB):         1  █
[ 64 KiB .. 128 KiB):   320,982  █████

realloc_growth_histogram:
[    1 B ..     2 B):        16  █
[    2 B ..     4 B):         0  
[    4 B ..     8 B):         0  
[    8 B ..    16 B):         0  
[   16 B ..    32 B):         0  
[   32 B ..    64 B):    25,477  ███
[   64 B ..   128 B):    14,976  █
[  128 B ..   256 B):     4,411  █
[  256 B ..   512 B):       106  █
[  512 B ..   1 KiB):         0  
[  1 KiB ..   2 KiB):         0  
[  2 KiB ..   4 KiB):         0  
[  4 KiB ..   8 KiB):         0  
[  8 KiB ..  16 KiB):         0  
[ 16 KiB ..  32 KiB):         0  
[ 32 KiB ..  64 KiB):   320,982  ████████████████████████████████████████
```

--------------------------------

### Initialize Global Allocator

Source: https://docs.rs/crate/heapster

Wrap the system allocator with Heapster to begin tracking heap metrics.

```rust
use heapster::Heapster;
use std::alloc::System;

#[global_allocator]
static GLOBAL: Heapster<System> = Heapster::new(System);

fn main() {
    // ... do some heavy work ...

    // See what has transpired in the heap
    println!("{}", GLOBAL.stats());
}
```

--------------------------------

### Add Heapster Dependency

Source: https://docs.rs/crate/heapster

Include the heapster crate in your project's Cargo.toml file.

```toml
[dependencies]
heapster = { version = "0.X" }
```

--------------------------------

### Measure Heap Usage

Source: https://docs.rs/crate/heapster

Use the measure method to capture heap statistics for a specific closure execution.

```rust
let (result, heap_diff) = GLOBAL.measure(|| operation_to_measure());
assert!(heap_diff.alloc_count < 10, "Regression: The operation allocated too many times!");
```
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