[jumpogpo]

Problem

When onOpen throws, PersistentConnection#loop() sets #connection to undefined but never closes the connection. That kind of error doesn't always mean the connection is already closed. A protocol-level error can be thrown while the socket is still open, for example when the server replies with an error but keeps the connection. After that nothing holds a reference to the connection, so it stays open until the peer closes it.

If onError returns 'reconnect', every such error leaks one more socket. In a real deployment this built up to ~10k sockets in ESTABLISHED state in a single process.

The default onError has the same problem. It returns 'close' for anything that isn't a ConnectionClosedError, the loop exits, and the connection is never closed.

Fix

Right after detaching the old connection, close it before calling onClose/onError. Any error from close() is ignored because the connection may already be closed. I also updated the onError doc comment to say it receives an already-closed connection in this case.

Testing

• Added regression tests for the 'reconnect' and 'close' actions. Both fail without the fix ("expected close to be called once, but got 0 times").
• vitest run packages/net: 149 passed. eslint and tsc report no errors.
• With the TCP repro below running for 1 second, the server is left with 8,258 open sockets before the fix and 0 after.

Repro (real TCP sockets)

import net from 'node:net'
import { PersistentConnection } from '@fuman/net'
import { connectTcp } from '@fuman/node'

// a server that replies with an error and keeps the socket open
const open = new Set()
const server = net.createServer((sock) => {
  open.add(sock)
  sock.on('close', () => open.delete(sock))
  sock.on('error', () => {})
  sock.write('ERR\n')
})
await new Promise(resolve => server.listen(0, '127.0.0.1', resolve))

const pc = new PersistentConnection({
  connect: addr => connectTcp(addr),
  strategy: () => 0,
  onOpen: async (conn) => {
    await conn.read(new Uint8Array(4))
    throw new Error('server replied with an error') // the socket is still open at this point
  },
  onError: () => 'reconnect',
})

pc.connect({ address: '127.0.0.1', port: server.address().port })
await new Promise(resolve => setTimeout(resolve, 1000))
await pc.close()
await new Promise(resolve => setTimeout(resolve, 200))

console.log('sockets still open on the server:', open.size) // before: thousands, after: 0
for (const s of open) s.destroy()
server.close()

---

AI-assisted: I investigated this and wrote the fix with help from Claude Opus 5.5 in Claude Code. I have reviewed the change and verified it myself.

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commit: e71a688