Crate allocative

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Crate implements lightweight memory profiler which allows object traversal and size introspection.

An object implementing Allocative trait is introspectable, and this crate provides two utilities to work with such objects:

Allocative overhead

When allocative is used, binary size is slightly increased due to implementations of Allocative trait, but it has no runtime/memory overhead when it is not used.

How it is different from other call-stack malloc profilers like jemalloc heap profiler

Allocative is not a substitute for call stack malloc profiler, it provides a different view on memory usage.

Here are some differences between allocative and call-stack malloc profiler:

  • Allocative requires implementation of Allocative trait for each type which needs to be measured, and some setup in the program to enable it
  • Allocative flamegraph shows object by object tree, not by call stack
  • Allocative shows gaps in allocated memory, e.g. spare capacity of collections or too large padding in structs or enums
  • Allocative allows profiling non-malloc allocations (for example, allocations within bumpalo)
  • Allocative allows profiling of memory for subset of the process data (for example, measure the size of RPC response before serialization)


  • Node in flamegraph tree.
  • Build a flamegraph from given root objects.
  • Hashed string, which is a key while descending into a tree (e.g. type name or field name).


  • This trait allows traversal of object graph.


Attribute Macros

Derive Macros