Date

2023-03-31

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Authors

Lukas Danek, CPO

Michael Zabka, CTO

Michal Artazov, DevOps Lead

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Summary:

On the 31st of March 2023, our production cluster experienced an issue where box responses were randomly slower than expected. This issue was caused by inefficient caching and was detected by our internal monitoring tool. This report aims to provide a detailed analysis of the impact, trigger, detection, root causes, and the steps taken for remediation.

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Impact:

The slowdown in box responses had a negative impact on the user experience. Users experienced delays and slower response times when interacting with boxes, leading to a degraded user experience. This issue affected the productivity and satisfaction of our customers, potentially resulting in reduced engagement with our platform and a negative perception of our service quality. No content playback was impacted, all devices run as expected.

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Trigger:

The trigger for the issue was the presence of inefficient caching within our system. The caching mechanism in place was not optimized to handle the increased load and varied response times, leading to inconsistent performance. The inefficient caching exacerbated the response time issues, resulting in slower box responses.

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Detection:

The issue was detected by our internal monitoring tool, which continuously collects and analyzes performance metrics from our production cluster. The tool alerted the team when it observed an increase in response times for box requests, exceeding the acceptable thresholds. Through proactive monitoring, we were able to identify the issue and initiate the investigation promptly.

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Root Causes:

After a thorough investigation, the following root causes were identified:

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Inefficient caching mechanism: The caching mechanism in use was not designed to handle the current workload and request patterns. The cache was not adequately tuned, leading to frequent cache misses and subsequent delays in box responses in the production environment.

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Insufficient automated testing on pre-production: The caching mechanism was not thoroughly tested under realistic production scenarios, and the system lacked optimization measures to address performance bottlenecks. This oversight resulted in the underperformance of the caching system during peak hours.

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Remediation:

To address the issue and prevent its recurrence, the following steps were taken:

Cache optimization: The caching mechanism was reevaluated and optimized to better handle the workload and improve response times. The cache sizing was adjusted, and caching algorithms were refined to minimize cache misses and improve overall performance.

Implementation of cache invalidation strategy: A comprehensive cache invalidation strategy was devised and implemented. This strategy ensures that outdated data is promptly removed from the cache, reducing the chances of serving stale responses.

Performance testing and tuning: Rigorous performance testing was conducted to simulate realistic production scenarios and identify performance bottlenecks. Based on the findings, optimizations were applied to various components of the system, including the caching mechanism, to enhance overall performance.

Enhanced monitoring and alerting: Our monitoring tool was enhanced to provide more granular visibility into cache performance metrics. This allows us to proactively detect and address any potential issues related to caching in real-time.

Continuous improvement and review: Regular reviews of the caching mechanism and its performance are now part of our operational practices. We prioritize ongoing optimization efforts and regularly evaluate the caching system to ensure it aligns with the evolving needs of our system and user requirements.

By implementing these remediation steps, we have significantly improved the performance and reliability of box responses, ensuring a better user experience for our customers.

We apologize for any inconvenience caused by this issue and appreciate your patience and understanding as we worked to resolve it promptly. Our team remains committed to continuously improving our system to provide the highest level of service to our users.

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If you have any further questions or concerns, please feel free to reach out to our support team.