circuitpython/docs/library/gc.rst

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2014-10-31 18:21:37 -04:00
:mod:`gc` -- control the garbage collector
==========================================
.. include:: ../templates/unsupported_in_circuitpython.inc
.. module:: gc
:synopsis: control the garbage collector
|see_cpython_module| :mod:`cpython:gc`.
Functions
---------
.. function:: enable()
Enable automatic garbage collection.
.. function:: disable()
Disable automatic garbage collection. Heap memory can still be allocated,
and garbage collection can still be initiated manually using :meth:`gc.collect`.
.. function:: collect()
Run a garbage collection.
.. function:: mem_alloc()
Return the number of bytes of heap RAM that are allocated.
.. admonition:: Difference to CPython
:class: attention
This function is MicroPython extension.
.. function:: mem_free()
Return the number of bytes of available heap RAM, or -1 if this amount
is not known.
.. admonition:: Difference to CPython
:class: attention
This function is MicroPython extension.
.. function:: threshold([amount])
Set or query the additional GC allocation threshold. Normally, a collection
is triggered only when a new allocation cannot be satisfied, i.e. on an
out-of-memory (OOM) condition. If this function is called, in addition to
OOM, a collection will be triggered each time after *amount* bytes have been
allocated (in total, since the previous time such an amount of bytes
have been allocated). *amount* is usually specified as less than the
full heap size, with the intention to trigger a collection earlier than when the
heap becomes exhausted, and in the hope that an early collection will prevent
excessive memory fragmentation. This is a heuristic measure, the effect
of which will vary from application to application, as well as
the optimal value of the *amount* parameter.
Calling the function without argument will return the current value of
the threshold. A value of -1 means a disabled allocation threshold.
.. admonition:: Difference to CPython
:class: attention
This function is a MicroPython extension. CPython has a similar
function - ``set_threshold()``, but due to different GC
implementations, its signature and semantics are different.