2b:null 2c:["$","title",null,{"children":"Memory Crashes | Chuncheng | Observable"}] 31:[] 2f:{"id":"941b4eb146658b08","slug":"memory-crashes","title":"Memory Crashes","thumbnail":"a3add78c4e89abd68c78e36368e3aa1d2de886fcbb2f611039bb23112ecbb7fa","access_level":"public","create_time":"$D2026-02-27T07:57:49.328Z","update_time":"$D2026-02-28T05:40:53.276Z","view_time":null,"first_public_time":"$D2026-02-27T09:38:04.717Z","fork":false,"stars":0,"starred":false,"owner":{"type":"team","id":"bcd65cef1cb4d2ed","login":"listenzcc","name":"Chuncheng","avatar_url":"https://avatars-next.observableusercontent.com/bb3c68e77a708a587ffc2d663bb83421f20d67991dbe6c1623c6e5d2fb73d15e","tier":"starter_2024"},"version":257,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"16328058352682a8","login":"listenzcc","name":"Chuncheng","avatar_url":"https://avatars-next.observableusercontent.com/bb3c68e77a708a587ffc2d663bb83421f20d67991dbe6c1623c6e5d2fb73d15e","tier":null}],"members":[{"type":"individual","id":"16328058352682a8","login":"listenzcc","name":"Chuncheng","avatar_url":"https://avatars-next.observableusercontent.com/bb3c68e77a708a587ffc2d663bb83421f20d67991dbe6c1623c6e5d2fb73d15e","tier":null,"role":"editor"},{"type":"team","id":"bcd65cef1cb4d2ed","login":"listenzcc","name":"Chuncheng","avatar_url":"https://avatars-next.observableusercontent.com/bb3c68e77a708a587ffc2d663bb83421f20d67991dbe6c1623c6e5d2fb73d15e","tier":"starter_2024","role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"subscribed":null,"forks":0,"collection":null,"type":"notebook","body":{"title":"Memory Crashes","cells":[{"id":0,"value":"# Memory Crashes\n\nIt simulates how the *continous array* crashes on limited memory.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":44,"value":"// Random chunk size\nrndSize = d3.randomUniform(10, 20)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":113,"value":"// Random age milliseconds\nrndAge = d3.randomUniform(2000, 5000)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":205,"value":"idealCapacity = 15 * 3.5 * 60","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":192,"value":"viewof memorySize = Inputs.range([2000, idealCapacity * 3], {\n label: \"memorySize\",\n step: 1,\n value: parseInt(idealCapacity * 1.5)\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":63,"value":"

\n Date:\n \n

\n LatestId:\n \n

\n Jobs:\n \n

\n FailedJobs:\n \n

\n MemoryView:\n

\n ${memory.str}\n

","pinned":true,"hidden":false,"mode":"html","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":251,"value":"(10).toString().padStart(8, \" \")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":55,"value":"{\n let memoryViewSpan = document.getElementById(\"memoryView\"),\n latestIdSpan = document.getElementById(\"latestId\"),\n dateSpan = document.getElementById(\"date\"),\n failedJobsSpan = document.getElementById(\"failedJobs\"),\n jobFreqSpan = document.getElementById(\"jobFreq\"),\n tic = new Date(),\n n = 0,\n latestIdx = -1,\n i,\n t;\n\n function loop() {\n i = startJob();\n n += 1;\n clearJobs();\n t = new Date();\n\n if (i > latestIdx) latestIdx = i;\n\n let ratio = (n / (t - tic)) * 1000,\n ratio1 = (failedJobs.length / (t - tic)) * 1000;\n\n jobFreqSpan.innerHTML =\n \"Total:\" + n + \" | \" + ratio.toFixed(3) + \" jobs per seconds\";\n memoryViewSpan.innerHTML = memory.str;\n latestIdSpan.innerHTML = `(${latestIdx}) | ${i}`;\n dateSpan.innerHTML = t;\n failedJobsSpan.innerHTML =\n failedJobs.length + \" | \" + ratio1.toFixed(3) + \" jobs per seconds\";\n requestAnimationFrame(loop);\n }\n\n loop();\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":79,"value":"jobs = {\n memorySize;\n return []\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":159,"value":"failedJobs = {\n memorySize;\n return [];\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":47,"value":"function startJob() {\n let str, i;\n\n str = mkStr();\n i = insertStr(str);\n\n if (i >= 0) {\n jobs.push({ i, str, expired: Date.now() + rndAge() });\n } else {\n failedJobs.push({ i, n: str.length });\n }\n return i;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":121,"value":"function clearJobs() {\n const now = new Date();\n\n let n;\n\n // To all the expired jobs\n jobs\n .filter(({ expired }) => now > expired)\n .map(({ i, str }) => {\n n = str.length;\n memory.str =\n memory.str.slice(0, i) +\n \"_\".repeat(n) +\n memory.str.slice(i + n, memorySize);\n });\n\n let expiredIdx = jobs\n .map((job, i) => (now > job.expired ? i : -1))\n .filter((i) => i > -1);\n\n expiredIdx.sort().reverse();\n expiredIdx.map((i) => {\n jobs.splice(i, 1);\n });\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":49,"value":"/**\n * Insert str into memory\n **/\nfunction insertStr(str) {\n const n = str.length,\n map = \"_\".repeat(n),\n i = memory.str.indexOf(map);\n\n if (i > -1) {\n // memory.str = memory.str.replace(map, str);\n memory.str =\n memory.str.slice(0, i) + str + memory.str.slice(i + n, memorySize);\n }\n\n return i;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":10,"value":"/**\n * Make random str\n **/\nfunction mkStr() {\n d3.shuffle(candidates);\n return candidates[0].repeat(rndSize());\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":5,"value":"memory = {\n return Object.assign({ str: \"_\".repeat(memorySize) });\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":39,"value":"candidates = {\n let array = [];\n for (let i = 0; i < alphabeta.length; ++i) {\n array.push(alphabeta[i]);\n }\n return array;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":34,"value":"alphabeta = \"abcdefghijklmnopqrstuvwxyz0123456789\"","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":31,"value":"d3 = require(\"d3\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W31","stdlib":"1","titling":"auto"}} 30:"$2f:body"