读取Arduino时反复出现File Descriptor out of range error求助

Hey there! I totally get how frustrating it is when a critical app stops working due to a weird error—especially when it’s supposed to run non-stop. Let’s tackle this step by step.

First, What’s Causing the File Descriptor Error? #

This error almost always means your program is using up too many system resources (like open files, network connections, or device ports) and not closing them properly. Every time your code opens a resource, the OS assigns a "file descriptor" to it. If you don’t release these descriptors, they pile up until the system runs out, and your app crashes.

Iterators themselves aren’t the problem—but if your iterator is part of a loop that keeps opening resources without closing them, that’s probably where the leak is happening.

Your Questions Answered #

1. Can I avoid using iterators entirely? #

Absolutely! Iterators are just a convenient way to loop through data in Python. You can replace them with a while loop or other control structures without any issues. For example, instead of:

for data in power_sensor_iterator:
    count_power(data)

You could do something like:

import time

while True:
    data = read_sensor_data()  # Your custom function to fetch sensor data
    if data is None:
        time.sleep(1)  # Wait before retrying if no data
        continue
    count_power(data)

The key here isn’t ditching iterators—it’s making sure any resources opened during each loop iteration get closed.

2. Do I need to stop the iterator? #

Since your app needs to run 24×7, you don’t want to stop the iterator permanently. But you do need to ensure that each iteration cleans up after itself. If your iterator is designed to run indefinitely (e.g., polling a sensor), the loop should keep going—but every time you open a file, socket, or device in that loop, you must close it when you’re done.

Critical Fixes to Try Right Now #

• Use with statements for all resource handling: This is Python’s built-in way to automatically close resources, even if an error occurs. For example, if you’re writing to a log file:

  with open("power_logs.txt", "a") as log_file:
      log_file.write(f"Power reading: {current_value} | Timestamp: {time.time()}\n")
  

  The with block ensures the file is closed as soon as you exit the block, no exceptions.
• Check your custom iterator (if you wrote one): If you have a custom iterator class, look at its __next__ method. Are you opening a resource there and never closing it? For example, if you’re using a serial port to read sensor data, make sure you either close it after each read or manage it with a with statement.
• Monitor resource usage: On Linux, you can run lsof -p <your_python_process_id> to see all open file descriptors for your app. If you see a growing number of entries, that’s a clear sign of a leak. In Python, you can use the tracemalloc module to track resource usage over time.
• Add small delays if needed: If your loop is running too fast (e.g., polling a sensor every millisecond), it might be opening/closing resources too frequently. Adding a time.sleep(0.1) (adjust the duration to fit your accuracy needs) can reduce the load and give the system time to clean up.

Share Your Code for More Help #

Since you’re self-taught, it’s totally normal to miss small details around resource management. If you can share a snippet of your code—especially the part with the iterator, the counter logic, or any places where you open files/connections—I can point out exactly where the leak might be and how to fix it.

内容的提问来源于stack exchange，提问作者Navjot Singh