We started migrating from Amazon Linux 2 (AL2) to Amazon Linux 2023 (AL2023) a month ago. While testing workloads on AL2023 in the pre-production environment, I noticed slightly higher disk utilization compared to the same workload on AL2. In this post, I'll share my investigation. AL2023 has less free disk space with …

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Our Go programs recently triggered an alarm due to excessive panics. Panic is a Go runtime mechanism that halts execution. It got me thinking about different ways a Go program can die. I don't expect many - not like A Million Ways to Die in the West. In this post, we'll go through the various ways Go programs die. …

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As the Amazon Linux 2 (AL2) approaches its End of Life on 2025-06-30, we have started migrating our container platform from AL2 to Amazon Linux 2023 (AL2023). The migration encountered a few speed bumps. In this post, we'll look at one of them: missing container disk I/O stats. Why are container I/O dashboards blank? …

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I've been building a service for a month and the day finally arrived when I had the artifact - an EC2 AMI. The AMI passed my "rigourous" manual tests, and I felt confident on a Ruby Tuesday, so I launched 100 EC2 instances using the AMI. Surprise! around 28 instances failed to launch. What is going on? All …

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Given an array of numbers A, find out whether it contains a 1-3-2 pattern. An 1-3-2 pattern is a subsequence of three numbers, A[i], A[j] and A[k] such that i<j<k and A[i] < A[k] < A[j]. For clarity, let's call the 1-3-2 pattern the Bronze-Gold-Silver pattern. If A[j] is Gold, then we should consider the …

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Tony Hoare invented QuickSort in 1961. At the time of its publication, the best comparison-based sorting algorithm was merge sort. Merge sort divides an unordered array into two equally sized subarrays, sorts each subarray, and then merge the two subarrays to produce a sorted array. Merge sort is simple to understand. …

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I often find myself confused by "upstream" and "downstream", in the context of software development. They bother me so much that I avoid using them in my own writing and I have to pause whenever I see them. In this post, I'll show a simple rule that helps you remember the difference: downstream adds …

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Modern CPUs operate significantly faster than memories. For instance, a 4.5 GHz x64 CPU operates 30 times faster than a 6000 MHz DDR5 memory of CAS Latency 36. Adding latencies incurred by the bus and memory coherency protocols, CPU access to memory could be 100 times slower than CPU access to registers. To mitigate …

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Given a non-decreasing array and a target value, we can find the target in logarithmic time using binary search. My first programming language is C++ and the C++ Standard Template Library (STL) provides two functions for this task. iterator lower_bound(first, last, value) returns the smallest index with a value larger …

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Problem Given an integer array A, in one step, remove all elements A[i] where A[i-1] > A[i]. Return the number of steps performed until A becomes a non-decreasing array. See examples at LeetCode 2289. Solution The naive approach executes steps one by one. Store integers in a Linked List. At each step, find all …

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