32 lines
1.9 KiB
JavaScript
32 lines
1.9 KiB
JavaScript
import v8 from 'v8';
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import { info, warn } from '../../build/output/log';
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import { italic } from '../picocolors';
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import { startObservingGc } from './gc-observer';
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import { startPeriodicMemoryUsageTracing } from './trace';
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export function enableMemoryDebuggingMode() {
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// This will generate a heap snapshot when the program is close to the
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// memory limit. It does not give any warning to the user though which
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// can be jarring. If memory is large, this may take a long time.
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if ('setHeapSnapshotNearHeapLimit' in v8) {
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v8.setHeapSnapshotNearHeapLimit(1);
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}
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// This flag will kill the process when it starts to GC thrash when it's
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// close to the memory limit rather than continuing to try to collect
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// memory ineffectively.
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v8.setFlagsFromString('--detect-ineffective-gcs-near-heap-limit');
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// This allows users to generate a heap snapshot on demand just by sending
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// a signal to the process.
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process.on('SIGUSR2', ()=>{
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warn(`Received SIGUSR2 signal. Generating heap snapshot. ${italic('Note: this will take some time.')}`);
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v8.writeHeapSnapshot();
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});
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startObservingGc();
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startPeriodicMemoryUsageTracing();
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warn(`Memory debugging mode is enabled. ${italic('Note: This will affect performance.')}`);
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info(' - Heap snapshots will be automatically generated when the process reaches more than 70% of the memory limit and again when the process is just about to run out of memory.');
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info(` - To manually generate a heap snapshot, send the process a SIGUSR2 signal: \`kill -SIGUSR2 ${process.pid}\``);
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info(' - Heap snapshots when there is high memory will take a very long time to complete and may be difficult to analyze in tools.');
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info(' - See https://nextjs.org/docs/app/building-your-application/optimizing/memory-usage for more information.');
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}
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//# sourceMappingURL=startup.js.map
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