@lodestar/beacon-node/lib/util/profile.js

A Typescript implementation of the beacon chain

import { sleep } from "@lodestar/utils";
/**
 * Take 10m profile of the current thread without promise tracking.
 */
export async function profileNodeJS(durationMs) {
    const inspector = await import("node:inspector");
    // due to some typing issues, not able to use promisify here
    return new Promise((resolve, reject) => {
        // Start the inspector and connect to it
        const session = new inspector.Session();
        session.connect();
        session.post("Profiler.enable", () => {
            session.post("Profiler.start", async () => {
                await sleep(durationMs);
                session.post("Profiler.stop", (err, { profile }) => {
                    if (!err) {
                        resolve(JSON.stringify(profile));
                    }
                    else {
                        reject(err);
                    }
                    // Detach from the inspector and close the session
                    session.post("Profiler.disable");
                    session.disconnect();
                });
            });
        });
    });
}
/**
 * Write heap snapshot of the current thread to the specified file.
 */
export async function writeHeapSnapshot(prefix, dirpath) {
    // Lazily import NodeJS only modules
    const fs = await import("node:fs");
    const v8 = await import("node:v8");
    const snapshotStream = v8.getHeapSnapshot();
    const filepath = `${dirpath}/${prefix}_${new Date().toISOString()}.heapsnapshot`;
    const fileStream = fs.createWriteStream(filepath);
    return new Promise((resolve, reject) => {
        fileStream.on("error", (err) => {
            reject(err);
        });
        snapshotStream.pipe(fileStream);
        snapshotStream.on("end", () => {
            resolve(filepath);
        });
    });
}
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