why the nodejs 16 generate heap dump file size is 0

[jiangxiaoqiang]

I want to generate a dump snapshot of the nodejs(v16.20.2) application. My application was running in docker and mounted the nas path /opt/data. First add the dump function follow this tutorial https://dev.to/bengl/node-js-heap-dumps-in-2021-5akm like this:

const memorySnapshot = () => {
  const snapshotStream = v8.getHeapSnapshot()
  // It's important that the filename end with `.heapsnapshot`,
  // otherwise Chrome DevTools won't open it.
  const fileName = `/opt/data/y-websocket-dump/${Date.now()}.heapsnapshot`
  const fileStream = fs.createWriteStream(fileName)
  snapshotStream.pipe(fileStream)
}

then invoke this function by send a http request. everything works fine, the dump was generated in the path, but now I found the dump file size is 0:

[root@k8smasterone y-websocket-dump]# ls -alh
total 1.0K
drwxr-xr-x 2 root root 4.0K Oct  7 00:15 .
drwxr-xr-x 8 root root 4.0K Oct  7 00:04 ..
-rw-r--r-- 1 root root    0 Oct  7 00:15 1696608905060.heapsnapshot

Am I missing something? What should I do to fixed this issue?

[bnoordhuis]

Most likely explanation is that you terminated the process before it was done writing out the snapshot.