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gc – Memory Management API Manual

This module implements a subset of the functionality of the CPython memory management module. For detailed information, please refer to the original CPython documentation: gc.

On K230, the following interfaces have been added to retrieve memory information of the RT-Smart system:

• sys_totoal: System memory size

• sys_heap: Used for memory management of kernel applications.

• sys_page: Used for memory management of user applications.

• sys_mmz: Used for multimedia driver memory management, applicable to modules such as Sensor and Display.

Functions

enable

gc.enable()

Enables automatic garbage collection.

disable

gc.disable()

Disables automatic garbage collection. When disabled, heap memory allocation is still possible, and garbage collection can be performed by manually calling gc.collect().

collect

gc.collect()

Manually runs the garbage collection process to reclaim memory that is no longer in use.

mem_alloc

gc.mem_alloc()

Returns the number of bytes of heap memory currently allocated.

Difference from CPython

This feature is an extension of MicroPython and is not included in CPython.

mem_free

gc.mem_free()

Returns the number of bytes of heap memory currently available. If the amount of remaining heap memory cannot be determined, it returns -1.

Difference from CPython

This feature is an extension of MicroPython and is not included in CPython.

threshold

gc.threshold([amount])

Sets or queries the allocation threshold for garbage collection. Garbage collection is typically triggered when heap memory is low. If a threshold is set, garbage collection will also be triggered after a total of more than the specified number of bytes have been allocated. The amount parameter is typically smaller than the entire heap size, with the purpose of triggering collection before the heap is exhausted to reduce memory fragmentation. The effect of this value varies by application, and the optimal value needs to be adjusted based on the application scenario.

When called without arguments, this function returns the current threshold setting. A return value of -1 indicates that the allocation threshold is disabled.

Difference from CPython

This function is a MicroPython extension. CPython has a similar set_threshold() function, but due to differences in garbage collection mechanisms, its signature and semantics differ.

sys_total

gc.sys_total()

Queries the system memory size, in bytes.

sys_heap

gc.sys_heap()

Queries the usage of the system heap memory, returning a tuple containing 3 elements representing total (total memory), used (used memory), and free (available memory), in bytes (Byte).

sys_page

gc.sys_page()

Queries the usage of the system page memory, returning a tuple containing 3 elements representing total (total memory), used (used memory), and free (available memory), in bytes (Byte).

sys_mmz

gc.sys_mmz()

Queries the usage of the system mmz memory, returning a tuple containing 3 elements representing total (total memory), used (used memory), and free (available memory), in bytes (Byte).