Crate allocative
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Allocative
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:
FlameGraphBuilderto build a flame graph of object treesize_of_unique_allocated_dataprovides estimation of how much allocated memory the value holds
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
Allocativetrait 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)
Structs
- 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).
Traits
- This trait allows traversal of object graph.
Functions
- Register global root which can be later traversed by profiler.
- Size of a piece of data and data allocated in unique pointers in the struct.
- Size of data allocated in unique pointers in the struct.