无法打开设备：打开的文件太多错误

Posted 2023-02-22

【中文标题】无法打开设备：打开的文件太多错误

【英文标题】：can't open device: Too many open files Error

【发布时间】：2017-10-24 07:54:20

【问题描述】：

嗨，我在 Raspberry Pi 3 中有糟糕的代码。我正在尝试阅读 4 RC522 模块，我可以做到。但几分钟后，我得到“无法打开设备：打开的文件太多”错误，我的 while 循环终止了。

我没有共享所有功能。我想重要的部分是while循环。我在每个循环中创建实例。我想这是一个很大的错误。我不能添加延迟。我尝试将 null 分配给我的对象，但我仍然遇到同样的错误。我的代码在下面

注意：我有 4 个 SPI 地址，我用它们创建实例。

#!/usr/bin/env python
# -*- coding: utf8 -*-
import time
import sys
import os
import RPi.GPIO as GPIO
import MFRC522
import signal
from time import gmtime, strftime
from time import sleep
import requests
#import xml.etree.ElementTree as ET
#import xmltodict, json
from lxml import objectify
from bs4 import BeautifulSoup
continue_reading = True

GPIO.setmode(GPIO.BOARD)
GPIO.setup(7, GPIO.OUT)
GPIO.setup(37, GPIO.OUT)
GPIO.setup(13, GPIO.OUT)
GPIO.setup(15, GPIO.OUT)

# Capture SIGINT for cleanup when the script is aborted
def end_read(signal,frame):
    global continue_reading
    print "Ctrl+C captured, ending read."
    continue_reading = False
    GPIO.cleanup()

kullanici = "xxxx"
sifre = "xxxx"
birim = "xxxx"
ogrKEY = " "


def end_read(signal,frame):
    global continue_reading
    print "Ctrl+C captured, ending read."
    continue_reading = False
    GPIO.cleanup()


# Hook the SIGINT
signal.signal(signal.SIGINT, end_read)

# Create an object of the class MFRC522
#
adresler = ["/dev/spidev0.0", "/dev/spidev0.1", "/dev/spidev1.0","/dev/spidev1.1"]

# Welcome message
print "Welcome to the MFRC522 data read example"
print "Press Ctrl-C to stop."
j = 0
# This loop keeps checking for chips. If one is near it will get the UID and authenticate
while continue_reading:
    MIFAREReader = None
    pin = 0
    if j == 100:
       j = 0
    i = j % 4

    if i == 0:
    MIFAREReader =  MFRC522.MFRC522(adresler[0], 16)
        pin = 15
    elif i == 1:
    MIFAREReader =  MFRC522.MFRC522(adresler[1], 18)
        pin = 13
    elif i == 2:
        MIFAREReader = MFRC522.MFRC522(adresler[2], 33)
        pin = 7
    else:
        MIFAREReader = MFRC522.MFRC522(adresler[3], 31)
        pin = 37


    # Scan for cards 
    (status,TagType) = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL)

    # If a card is found
    if status == MIFAREReader.MI_OK:
       print "Card detected"

       # Get the UID of the card
       (status,uid) = MIFAREReader.MFRC522_Anticoll()

       # If we have the UID, continue
       if status == MIFAREReader.MI_OK:
              # print "su okuyucudan okundu" % i
           # Print UID
           print "Card read UID: "+str(uid[0])+","+str(uid[1])+","+str(uid[2])+","+str(uid[3])

           # This is the default key for authentication
           key = [0xFF,0xFF,0xFF,0xFF,0xFF,0xFF]
           # Select the scanned tag
           MIFAREReader.MFRC522_SelectTag(uid)

           # Authenticate
           status = MIFAREReader.MFRC522_Auth(MIFAREReader.PICC_AUTHENT1A, 10, key, uid)

           # Check if authenticated
           if status == MIFAREReader.MI_OK:
               MIFAREReader.MFRC522_Read(10)
           ogrKEY = MIFAREReader.returnOGR()
                   sonuc =  parser(ogrKEY)
                   if sonuc == True:
            openTurnsTile(pin)
                   else:
            sonuc = personelKontrol(ogrKey)
                        if sonuc == True:
                openTurnsTile(pin)
               MIFAREReader.MFRC522_StopCrypto1()
           else:
               print "Authentication error"
    j = j + 1

【参考方案1】：

当您创建 MFRC522 对象时，它实际上调用了spi.openSPI()，但从不关闭它。这个 python 库适用于单实例，但现在您正在处理打开 FD 的多个实例，也需要使用 spi.closeSPI() 关闭，否则您将收到错误“打开的 FD 太多”。

检查您的 PID 中有多少 open FDs。

【讨论】：

没有closeSPI函数:(

对不起，我找到了，closeSPI 函数自然在 spi 库中，很抱歉 :) 谢谢。

如果这有帮助，你能放弃投票吗？谢谢:)