Fix: Startup Delay Due To Unreachable Raw.githubusercontent.com

by Rajiv Sharma 64 views

Hey guys! We've got a tricky bug to tackle today. It seems like some users are experiencing a significant delay during startup, and the culprit appears to be an inability to reach raw.githubusercontent.com. Let's dive into the details and figure out what's going on and how to fix it.

Understanding the Issue

From the logs, we can see a pretty big gap – about 9 minutes – between two messages:

2025-08-03 18:26:25.146 | INFO | src.backend.PageManagement.PageManagerBackend:remove_old_backups:448 - Removed old page backups: 2025-08-03T18:17:42.501906

2025-08-03 18:35:23.231 | ERROR | src.backend.Store.StoreBackend:request_from_url:110 - HTTPSConnectionPool(host='raw.githubusercontent.com', port=443): Max retries exceeded with url: /StreamController/StreamController-Store/1.5.0/OfficialAuthors.json (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7f1945b8aab0>: Failed to establish a new connection: [Errno 101] Network is unreachable'))

This delay happens because the application is trying to fetch OfficialAuthors.json from raw.githubusercontent.com, but it's failing with a Network is unreachable error. This is a critical issue because it directly impacts the user experience, making the application feel slow and unresponsive. Imagine waiting almost ten minutes just for an application to start – not a great first impression!

Why is raw.githubusercontent.com so important? Well, it seems our application relies on it for fetching some essential data, in this case, a list of official authors. This could be for various reasons, such as verifying content sources, displaying author information, or even updating application settings. Understanding why we need this file is crucial for finding the best solution. Is it a one-time fetch during startup, or is it required periodically? This will influence our approach to fixing the problem.

How to reproduce the issue? It's actually pretty straightforward. You can simulate this problem by blocking raw.githubusercontent.com using tools like OpenSnitch, Little Snitch, or Pi-hole. This is a great way to test the fix once we have one. By blocking the domain, we force the application to encounter the same error, allowing us to confirm if our solution works as expected. We can confidently say that the problem lies in the application's inability to handle a failed network connection to raw.githubusercontent.com gracefully.

Affected version: 1.5.0-beta.11 on Arch Linux.

Diving Deeper: Root Cause Analysis

Let's get down to the nitty-gritty of why this is happening. The error message Network is unreachable suggests a fundamental network connectivity issue. This could be due to a few reasons:

  1. Firewall or Network Configuration: As the user pointed out, blocking raw.githubusercontent.com directly causes the issue. This highlights that a firewall rule or network configuration might be preventing the application from accessing the internet. It’s essential to consider that users might have legitimate reasons for blocking certain domains, such as privacy concerns or network policies.

  2. DNS Resolution Problems: The application might be unable to resolve the domain name raw.githubusercontent.com to an IP address. This could be due to a DNS server outage or a misconfigured DNS setting on the user's machine. While less likely, it's still a possibility worth investigating. DNS issues can be tricky because they can be intermittent and difficult to diagnose.

  3. Temporary Network Outage: The user's internet connection might have been temporarily down when the application started. While this is a transient issue, we should still handle it gracefully to prevent long startup delays.

  4. Rate Limiting: GitHub might be rate-limiting requests from the application if it's making too many requests in a short period. While less likely for a startup sequence, it's something to keep in mind, especially if the application fetches data frequently from raw.githubusercontent.com. Rate limiting is a common practice for APIs to prevent abuse and ensure fair usage.

  5. SSL/TLS Issues: There might be problems with the SSL/TLS handshake if the user's system has an outdated or misconfigured certificate store. This could prevent the application from establishing a secure connection to raw.githubusercontent.com.

  6. Application Logic: The most crucial aspect to consider is how the application handles network errors. Does it have proper error handling and retry mechanisms in place? If the connection fails, does it simply give up and block the startup process, or does it try again after a delay? This is where we can make the most significant improvements.

To get a clearer picture, we need to analyze the src.backend.Store.StoreBackend:request_from_url function. This is where the network request is being made, and it's where we'll likely find the source of the problem. We need to understand how it handles exceptions, how many times it retries, and what happens if all retries fail. Let's consider a scenario where a user is on a flaky network. If the application tries to download the file only once and fails, the user has to wait a significant amount of time. But if it implemented a retry mechanism, it might succeed on a subsequent attempt, providing a better user experience.

Potential Solutions: Let's Fix This!

Okay, so we know what's causing the problem. Now, let's brainstorm some solutions to make our application more resilient to network issues.

  1. Implement a Retry Mechanism with Exponential Backoff: This is a classic solution for dealing with transient network errors. Instead of failing immediately, the application should retry the request a few times, with increasing delays between each attempt. For example, it could try again after 1 second, then 2 seconds, then 4 seconds, and so on. This gives the network time to recover without overwhelming the system with retries. Exponential backoff is a smart strategy because it avoids hammering the server while still giving the connection a chance to succeed.

  2. Cache the OfficialAuthors.json Locally: If the OfficialAuthors.json file doesn't change very often, we can cache it locally on the user's machine. This way, the application can load the data from the cache if it can't reach raw.githubusercontent.com. We'll need to implement a mechanism for refreshing the cache periodically, but this can be done in the background without blocking the startup process. Caching can significantly improve performance and reduce reliance on network connectivity.

  3. Provide a Graceful Fallback: If we can't fetch the OfficialAuthors.json file, the application shouldn't just hang. Instead, it should provide a graceful fallback, such as displaying a default list of authors or showing an error message that informs the user about the issue and suggests possible solutions (e.g., checking their internet connection). A good user experience is key, and a graceful fallback prevents frustration.

  4. Asynchronous Loading: Fetching the OfficialAuthors.json file should be done asynchronously so it doesn't block the main thread and delay the application startup. This means the application can continue starting up while the file is being downloaded in the background. Asynchronous operations are crucial for maintaining responsiveness.

  5. Configuration Option: Consider adding a configuration option that allows users to specify a local path to the OfficialAuthors.json file. This would allow users who are intentionally blocking raw.githubusercontent.com to still use the application by providing their own version of the file. Flexibility is important, especially for advanced users.

  6. Improve Error Logging: Add more detailed error logging to the request_from_url function. This will help us diagnose future network issues more easily. We should log not only the error message but also the URL being requested, the number of retries, and any other relevant information. Good logging is essential for debugging and monitoring.

  7. Timeout: Implement timeout for request, if timeout happens after a certain time, stop trying to connect and use cache file, if exists. Timeouts provide a necessary safety net to prevent indefinite waiting.

  8. Check Network Connectivity: Before attempting to download the JSON, it would be wise to perform a preliminary check for network connectivity. This could involve a simple ping to a reliable external server, such as Google's DNS server (8.8.8.8). If there's no connectivity, the application can immediately resort to using cached data or displaying an appropriate error message, bypassing the lengthy wait for a failed connection attempt to raw.githubusercontent.com.

Implementing the Fix: A Step-by-Step Approach

Okay, we've got a solid plan. Now, let's break down how we can implement these solutions:

  1. Focus on the Retry Mechanism First: This is the most crucial step. We need to modify the request_from_url function in src.backend.Store.StoreBackend to include a retry mechanism with exponential backoff. This will address the immediate issue of long startup delays. Start by wrapping the network request in a try...except block to catch potential exceptions, such as urllib3.exceptions.NewConnectionError and requests.exceptions.RequestException. Then, implement a loop that retries the request a certain number of times, increasing the delay between each attempt using a formula like delay = 2 ** retry_count. Remember to log each retry attempt and the reason for the failure.

  2. Implement Caching: Next, we'll add caching for the OfficialAuthors.json file. We can store the file in a local directory and load it from there if the network request fails. We'll need to add a timestamp to the cached file and refresh it periodically (e.g., every 24 hours) by fetching it from raw.githubusercontent.com. Consider using a library like diskcache to simplify caching.

  3. Add Asynchronous Loading: To prevent blocking the main thread, we'll make the fetching of OfficialAuthors.json asynchronous. We can use Python's asyncio library or a threading pool to run the network request in the background. This will ensure the application remains responsive during startup.

  4. Implement Graceful Fallback: If all retries fail and the cache is empty, we'll display a user-friendly error message and potentially use a default list of authors. This will prevent the application from getting stuck in a loading state.

  5. Add Configuration Option (Optional): If we want to provide maximum flexibility, we can add a configuration option that allows users to specify a local path to the OfficialAuthors.json file. This will be useful for users who intentionally block raw.githubusercontent.com.

  6. Testing, Testing, Testing: After implementing these changes, we need to thoroughly test them. We can use the same method the user described – blocking raw.githubusercontent.com using tools like OpenSnitch or Pi-hole – to simulate network issues. We should also test with different network conditions, such as slow connections and intermittent outages. Testing is crucial to ensure the fix works as expected in real-world scenarios.

Conclusion: A More Resilient Application

By implementing these solutions, we can make our application much more resilient to network issues and provide a better user experience. The key is to handle errors gracefully, retry failed requests, cache data locally, and perform operations asynchronously. This bug, while frustrating for users, is a great opportunity for us to improve the robustness and reliability of our application. Let's get to work and make it happen!