Exponential backoff with jitter on client reconnection, not fixed retry interval

When a server restarts or drops a connection, every client attempts to reconnect. If all clients retry at the same fixed interval — say, 5 seconds — they form a synchronized stampede that hits the server simultaneously on each retry cycle. This thundering-herd effect can prevent the server from recovering under its own load. Jitter randomizes reconnect timing so the server receives a spread of reconnect requests it can absorb incrementally. ISO 25010 reliability includes resistance to self-inflicted load spikes of exactly this type.

Implement exponential backoff with additive jitter on the client, capped at a maximum delay to prevent indefinitely long waits.

const MAX_BACKOFF = 30_000; // 30 s
let attempt = 0;

function scheduleReconnect() {
  const base   = Math.min(1_000 * 2 ** attempt, MAX_BACKOFF);
  const jitter = Math.random() * base;
  setTimeout(() => socket.connect(), base + jitter);
  attempt++;
}

socket.on('disconnect', scheduleReconnect);
socket.on('connect',    () => { attempt = 0; });

If you use Socket.IO's built-in reconnection, set reconnectionDelayMax and randomizationFactor rather than implementing your own loop — the default reconnectionDelay of 1 s without jitter is a partial fix only.

• ID: exponential-backoff-jitter

• Severity: high

• What to look for: Enumerate all reconnection logic in client-side code. Count the retry mechanisms: exponential backoff calculation, jitter randomization, MAX_BACKOFF cap. Quote the actual delay formula if found.

• Pass criteria: The client implements exponential backoff with jitter for reconnection attempts. Delays grow with each attempt but are capped at a maximum of no more than 60 seconds. At least 1 jitter mechanism must be present.

• Fail criteria: The client uses a fixed retry interval (e.g., always 5 seconds), or no jitter is applied.

• Skip (N/A) when: Never — clients should use exponential backoff to avoid thundering herd.

• Detail on fail: "Client uses fixed 5-second retry interval with no jitter. If the server goes down, all clients will reconnect simultaneously."

• Remediation: Implement exponential backoff with jitter on the client:

  const MAX_BACKOFF = 30000; // 30 seconds
  let retryCount = 0;
  
  function reconnect() {
    const backoff = Math.min(1000 * Math.pow(2, retryCount), MAX_BACKOFF);
    const jitter = backoff * Math.random();
    const delay = backoff + jitter;
  
    setTimeout(() => {
      socket.connect();
      retryCount++;
    }, delay);
  }
  
  socket.on('disconnect', () => {
    reconnect();
  });
  
  socket.on('connect', () => {
    retryCount = 0; // Reset on successful connection
  });