[Python-Dev] Another Proposal: Run GC less often (original) (raw)

none ralfs72 at googlemail.com
Sat Jun 21 23:28:22 CEST 2008

Instead of collecting objects after a fixed number of allocations (700) You could make it dynamic like this:

initial values

min_allocated_memory = 0 max_allocated_memory = 0 next_gc_run = 1024 * 1024

def manage_memory(): allocated_memory = get_allocated_memory() min_allocated_memory = min(min_allocated_memory, allocated_memory) max_allocated_memory = max(max_allocated_memory, allocated_memory)

 if max_allocated_memory - min_allocated_memory > next_gc_run:
     # run the gc
     memory_freed, allocated_memory = run_gc()
     next_gc_run = max(
         allocated_memory * 1.5 - memory_freed, 1024 * 1024
     )
     min_allocated_memory = allocated_memory
     max_allocated_memory = allocated_memory

manage_memory() should be called after every allocation and after a ref count of an object reaches 0 (memory is freed)

Expected behaviours:

=> As less objects contain cyclic references as less often the GC will run (memory_freed is small)

=> As more objects contain cyclic references as more often the GC will run (memory_freed is large)

=> If memory utiliaziation grows fast (burst allocations) GC will run less often: next_gc_run = allocated_memory * 1.5 - memory_freed

... Of course the constants: 1.5 and 1024 * 1024 are only suggestions...

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