API调用缓存导致重复执行失败，如何彻底清除缓存并重试？

Got it, let's figure out why your MechanicalSoup-based buy loop is stuck failing repeatedly—caching is a solid suspect here, since MechanicalSoup relies on requests.Session which can hold onto cached responses or stale session data. Here are practical steps to fix this:

1. Disable Caching via Session Headers #

Requests (and by extension MechanicalSoup) will cache responses by default for GET requests, and even POSTs can hit server-side caching. Add headers to your browser session that explicitly tell the server to skip cached content:

import mechanicalsoup

# Initialize browser with anti-cache headers
browser = mechanicalsoup.Browser()
browser.session.headers.update({
    'Cache-Control': 'no-cache, no-store, must-revalidate',
    'Pragma': 'no-cache',
    'Expires': '0'
})

# Then use this browser in your buy function
while True:
    try:
        print("trying to buy a")
        buy(ashr, tickers[0], client, browser)  # Pass the configured browser
    except Exception as e:
        print(f"Retry after error: {str(e)}")  # Log errors to debug!
        continue
    break

2. Reset the Entire Session on Each Retry #

If stale cookies or session state are the problem, creating a fresh browser instance every time you retry ensures you start with a clean slate:

while True:
    try:
        print("trying to buy a")
        # Create a new browser session for each attempt
        fresh_browser = mechanicalsoup.Browser()
        # Reinitialize your client with this fresh browser if needed
        fresh_client = your_client_setup_function(fresh_browser)
        buy(ashr, tickers[0], fresh_client)
    except Exception as e:
        print(f"Error encountered: {str(e)}")
        continue
    break

3. Manually Clear Cookies Between Attempts #

If you don't want to recreate the whole browser, just clear the cookies stored in the session to avoid stale state:

browser = mechanicalsoup.Browser()
while True:
    try:
        print("trying to buy a")
        # Wipe cookies before each request
        browser.session.cookies.clear()
        buy(ashr, tickers[0], client)
    except Exception as e:
        print(f"Retrying: {str(e)}")
        continue
    break

4. Verify You're Not Using Cached Responses #

Add a check in your buy function to confirm if the response is coming from cache—this will help confirm if caching is indeed the issue:

def buy(ashr, ticker, client):
    # ... your existing form-filling code ...
    response = client.submit(form)
    # Check if the response was cached
    if hasattr(response, 'from_cache') and response.from_cache:
        print("WARNING: Got cached response!")
        # Handle this case (e.g., retry immediately)
        raise ValueError("Cached response received")
    # ... rest of your buy logic ...

Pro Tip: Avoid Bare except Clauses #

Your current code uses a bare except, which catches all exceptions (including keyboard interrupts) and hides useful error details. Replace it with specific exceptions to debug what's actually failing:

except (requests.exceptions.RequestException, mechanicalsoup.FormNotFoundError) as e:
    print(f"Request/form error: {str(e)}")
except Exception as e:
    print(f"Unexpected error: {str(e)}")

内容的提问来源于stack exchange，提问作者Carson P