Malloc supplies threadsafe concurrent memory allocator useful for MVCC friendly storage data structures.
- Work best when memory behaviour is known apriori.
- Memory is allocated in pools, of several Megabytes, where each pool manages several memory-chunks of same size.
- Once a pool block is allocated from OS, it is not automatically given back to OS. Pools are freed only when the entire arena is released.
- There is no pointer re-write, if copying garbage collector is necessary it can be implemented on top of this implementation.
- Memory-chunks allocated by this package will always be 8-byte aligned.
Arena is a bucket space of memory, with a maximum capacity, that is empty to begin with and starts filling up as and when new allocations are requested by application.
Slabs are created from 0 to 1TB of memory. Between 0 bytes and
1Terabyte, sizes are rounded off to discrete slabs. For example,
when memory-chunk of size 67 is requested, it will be allocated
from a slab of size 72. Organizing chunk sizes in slabs can help
reduce the overhead cost and improve performance.
Memory for each slab-size will be managed in pools. A pool of memory
can contain several memory-chunks of same size. Memory is obtained
from OS in pool-size, which is calculated using a fair-model on
the assumption that there will be equal number of allocations required
from each slab. This issue is tracked under #30. Number of chunks in
a pool cannot exceed Maxpools and a slab cannot contain more than
Maxpools.
Memory-chunk is the basic unit of allocation in a pool and it is always greater than or equal to the requested memory by application.
Panics are to expected when APIs are misused. Programmers might choose to ignore the errors, but not panics. For example:
- When arena's requested capacity exceeds Maxarenasize, which is typically 1TB.
- When Free() is called on arena, call Free on the pool.
- When Arena runs Out-Of-Memory.
- When trying to free a nil pointer.