QUERY · ISSUE

constrained

openby peterhinchopened 2017-06-11updated 2017-07-02

docs

This has

gc.threshold((gc.mem_free() + gc.mem_alloc()) // 4)

which sets the threshold to 1/4 of the total RAM regardless of the amount allocated. Shouldn't this read

gc.threshold(gc.mem_free() // 4 + gc.mem_alloc())

to account for RAM already allocated?

CANDIDATE · ISSUE

ESP32: no default gc threshold

openby miketeachmanopened 2018-06-05updated 2024-09-29

enhancementport-esp32

Latest stable firmware (esp32-20180511-v1.9.4.bin) does not appear to have a garbage collection threshold. running gc.threshold() in the REPL returns -1. gc.isenabled() returns True. Running in a loop will take the free heap space to zero, with no automatic gc.

Is there a reason for this default configuration? The esp8266 has an out-of-the-box gc threshold of 8992.

Assessment

Q Qwen · high

Both issues concern garbage collection threshold behavior in MicroPython, but they address different problems. Issue #3138 is a documentation question about the correctness of a formula in the constrained systems documentation (whether the threshold calculation should account for already-allocated RAM). Issue #3840 is a feature request/bug report about ESP32 firmware lacking a default GC threshold configuration (gc.threshold() returns -1). While both involve gc.threshold(), the root causes and solutions are different: one is about documentation accuracy for a formula, the other is about missing default configuration in a specific port.

Suggested action

Keep both issues open as they address distinct problems. Issue #3138 should be reviewed for documentation accuracy, while #3840 needs investigation into why ESP32 lacks a default GC threshold compared to ESP8266.

gc threshold calculation in docs/reference/constrained

ESP32: no default gc threshold

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