nodejs
Does Node.js Buffer.alloc not occupy memory space when it is not filled
Node.js Version
v17.4.0
NPM Version
v8.3.1
Operating System
Darwin Kernel Version 21.6.0
Subsystem
buffer
Description
const format = function (bytes) {
return (bytes / 1024 / 1024).toFixed(2) + ' MB';
};
const memoryUsage = function() {
const memoryUsage = process.memoryUsage();
return JSON.stringify({
rss: format(memoryUsage.rss),
heapTotal: format(memoryUsage.heapTotal),
heapUsed: format(memoryUsage.heapUsed),
external: format(memoryUsage.external),
arrayBuffers: format(memoryUsage.arrayBuffers),
})
}
async function main() {
const arr = []
setInterval(() => {
arr.push(Buffer.alloc(100 * 1024 * 1024))
console.log(arr.length, memoryUsage())
}, 100)
}
main()
The memoryUsage.external memory size has exceeded the limit, but the program is normal. In the monitor, the node process does not occupy a high amount of memory; What's going on here?
Minimal Reproduction
No response
Output
115 {"rss":"26.31 MB","heapTotal":"5.27 MB","heapUsed":"3.43 MB","external":"11500.41 MB","arrayBuffers":"11500.01 MB"} 116 {"rss":"26.31 MB","heapTotal":"5.27 MB","heapUsed":"3.43 MB","external":"11600.41 MB","arrayBuffers":"11600.01 MB"} 117 {"rss":"26.31 MB","heapTotal":"5.27 MB","heapUsed":"3.43 MB","external":"11700.41 MB","arrayBuffers":"11700.01 MB"} 118 {"rss":"26.31 MB","heapTotal":"5.27 MB","heapUsed":"3.43 MB","external":"11800.41 MB","arrayBuffers":"11800.01 MB"} 119 {"rss":"26.31 MB","heapTotal":"5.27 MB","heapUsed":"3.43 MB","external":"11900.41 MB","arrayBuffers":"11900.01 MB"} 120 {"rss":"26.31 MB","heapTotal":"5.27 MB","heapUsed":"3.43 MB","external":"12000.41 MB","arrayBuffers":"12000.01 MB"} 121 {"rss":"26.31 MB","heapTotal":"5.27 MB","heapUsed":"3.43 MB","external":"12100.41 MB","arrayBuffers":"12100.01 MB"}
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