diff options
Diffstat (limited to 'doc/gc.txt')
| -rw-r--r-- | doc/gc.txt | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/doc/gc.txt b/doc/gc.txt index 854f9ce2a..18fb03b6d 100644 --- a/doc/gc.txt +++ b/doc/gc.txt @@ -13,7 +13,7 @@ Introduction This document describes how the GC works and how to tune it for (soft) `realtime systems`:idx:. -The basic algorithm is *Deferrent Reference Counting* with cycle detection. +The basic algorithm is *Deferred Reference Counting* with cycle detection. References on the stack are not counted for better performance (and easier C code generation). The GC **never** scans the whole heap but it may scan the delta-subgraph of the heap that changed since its last run. @@ -107,3 +107,20 @@ that up to 100 objects are traversed and freed before it checks again. Thus ``workPackage`` affects the timing granularity and may need to be tweaked in highly specialized environments or for older hardware. + +Keeping track of memory +----------------------- + +If you need to pass around memory allocated by Nimrod to C, you can use the +procs ``GC_ref`` and ``GC_unref`` to mark objects as referenced to avoid them +being freed by the GC. Other useful procs from `system <system.html>`_ you can +use to keep track of memory are: + +* getTotalMem(): returns the amount of total memory managed by the GC. +* getOccupiedMem(): bytes reserved by the GC and used by objects. +* getFreeMem(): bytes reserved by the GC and not in use. + +In addition to ``GC_ref`` and ``GC_unref`` you can avoid the GC by manually +allocating memory with procs like ``alloc``, ``allocShared``, or +``allocCStringArray``. The GC won't try to free them, you need to call their +respective *dealloc* pairs when you are done with them or they will leak. |