Do not re-open the SPI handle on every module_init() - #429
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RaspberryPi.module_init() calls self.SPI.open(0, 0) unconditionally. spidev's open() does not close an existing handle, so every call after the first leaks one /dev/spidev0.0 file descriptor. This is reachable from the documented API. Switching a panel between 4Gray and 1Gray requires calling init(mode) again, and the bundled example does exactly that: epd_3in7_test.py calls init(0), init(1), then init(0), with a single module_exit() at the end, leaking two descriptors per run. A long-running program that redraws periodically hits the process NOFILE limit. Measured on a Pi 3B refreshing an epd3in7 once a minute: 1024 descriptors held, 1012 of them spidev, after 16.7 hours. Past that the process cannot open a socket either, so unrelated network calls start failing with EINVAL. Fixed with the same Flag guard SunriseX3.module_init() already uses in this file, and reset in module_exit() so a genuine teardown still re-opens. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Fixes #428.
RaspberryPi.module_init()callsself.SPI.open(0, 0)unconditionally.spidev'sopen()does not close an existing handle, so every call after the first leaks one/dev/spidev0.0file descriptor.This is reachable from the documented API — switching a panel between 4Gray and 1Gray requires calling
init(mode)again, andexamples/epd_3in7_test.pydoes exactly that (init(0),init(1),init(0), with a singlemodule_exit()), leaking two descriptors per run.Measured on a Pi 3B refreshing an
epd3in7once a minute: 1024 descriptors held, 1012 of them spidev, after 16.7 hours. Past theNOFILEceiling the process could no longer open a socket either, so unrelated HTTPS calls began failing with[Errno 22] Invalid argument— which is what makes this awkward to diagnose. Full write-up in #428.The change
Uses the guard
SunriseX3.module_init()already uses a few classes down in this same file, so the two implementations now behave consistently:Flag = 0class attribute onRaspberryPi, matchingSunriseX3module_init()opens SPI only whenFlag == 0module_exit()resetsFlagso a genuine teardown still re-opensOnly the
cleanup=Falsebranch is guarded; thecleanup=Truepath usesDEV_SPIand is untouched.Behaviour
module_init()module_exit()thenmodule_init()No API change, and no change for callers that already do a single
init()/module_exit().Verified on the affected hardware: a Pi 3B driving an
epd3in7at one refresh per minute now holds a steady 13 file descriptors, 1 of them spidev, across sustained operation — previously it gained one per minute until it died.🤖 Generated with Claude Code