Production Bugs

How to experiment with cache coherence (MESI) and cache eviction across cores using shared memory?

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Incident Report: Uncontrolled Cache Thrashing During MESI Protocol Experiment Summary A cache-coherence experiment caused severe source degradation due to uncontrolled cache thrashing and False Sharing in a shared memory region. The experiment pinned processes to different cores and measured memory latency via rdtsc, but inadvertently triggered L1-cache saturation and core-to-core coherence stalls lasting 150ms, affecting … Read more

How can the backward function in tensor influence the matrix in model

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How Backward Functions Influence Model Parameters in PyTorch: An Autograd Postmortem Summary Gradients weren’t updating during training due to improper Tensor detachment during model initialization. The model explicitly detached .weight and .bias tensors during initialization (detach().zero_()), preventing PyTorch’s autograd system from connecting computation graphs to trainable parameters. Root Cause The core issue stems from PyTorch’s … Read more

Blogspot Doesn’t show all my drop down menu on Mobile

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Summary The issue at hand is that Blogspot’s drop-down menu is not displaying all items on mobile devices, specifically showing only 4 out of 7 list items. This problem is related to CSS media queries and responsive design. Root Cause The root cause of this issue is due to the following reasons: Insufficient max-height in … Read more

Is it possible to get all the text from text field?

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Postmortem: Text Field Extraction Limitations in iOS Keyboard Extensions Summary An attempt to retrieve the entire text from a text field via documentContextBeforeInput and “ in an iOS keyboard extension unexpectedly returned only ~200 characters. This occurs due to technical constraints生怕Apple’s keyboard API deliberately restricts surrounding text exposure for performance and security. Root Cause System-enforced … Read more

JMS destination lookup error on JBOSS EAP 8

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Summary The JMS destination lookup error on JBOSS EAP 8 occurs when the application attempts to look up a JMS queue or topic using the InitialContext. The error is caused by a ClassNotFoundException for the ActiveMQJMSConnectionFactory class. This issue arises due to a missing dependency or incorrect configuration in the application. Root Cause The root … Read more

Unity Google Play Games Leaderboard not showing

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Summary After integrating Google Play Games into a Unity project, leaderboard UI fails to display despite successful authentication. The issue persists in production builds with no apparent logs. Investigation reveals the absence of a leaderboard activation step and failure to await authentication completion before calling ShowLeaderboardUI. Root Cause Authentication and leaderboard display workflows were incompatible … Read more

I want to join freelancing team as free gick

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## Summary On 2023-10-05, users attempting to discover freelancing opportunities via Freelancer.com’s API unexpectedly received zero results for MERN stack queries. This was caused by an API endpoint regression silently dropping search results matching Mongo⁠DB criteria. **Key symptom:** Valid searches returned empty lists with HTTP 200 status despite matching opportunities existing in the database. ## … Read more

Search and return a specific IP in array

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其中的关键在于使用JSONata进行数组过滤操作。 ## Summary A developer attempted to retrieve a specific IP address from an unordered array of IP addresses in a JSON document using JSONata. The challenge arose because the array elements were not guaranteed to be in a fixed order, requiring a search method rather than positional access. This highlighted a gap in understanding … Read more

Why is the online compiler complaining that **long double m_p=1.67262192595e−27L;** as the error **main.c:9:21: error: exponent has no digits**?

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Summary This postmortem details a compilation error encountered in a C program that calculates the ionization energy of Hydrogen using long double precision. The error main.c:9:21: error: exponent has no digits appeared due to invalid Unicode characters masquerading as mathematical operators and multiple C syntax violations. The solution required replacing Unicode exponents and fixing syntax … Read more

Plotly, have one dropdown menu for each level in DataFrame multi-index

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Summary The question revolves around creating an interactive 3D scatter plot with multiple dropdown menus for a multi-indexed DataFrame using Plotly. The goal is to have one dropdown menu for each level in the DataFrame’s multi-index, allowing for efficient selection and visualization of data, especially when dealing with large datasets. Root Cause The root cause … Read more