WebSocketProvider vs HttpProvider: Real‑Time Events vs Stateless Stability

Answer first

No. Unsubscribing and disconnecting after each subscription does not fully prevent memory growth in long-running services, and it defeats the purpose of a persistent WebSocket. Disconnecting per subscription forces reconnect churn, latency spikes, and event loss. A single WebSocketProvider can be kept open for all components, but only with strict centralized lifecycle ownership. Without central tracking, listener accumulation will continue in web3.js v1.5.x.

Confirmed facts

• HttpProvider is stateless HTTP JSON-RPC. It has no persistent connection and no subscriptions. Real-time events require polling, which increases network load but avoids client-side listener accumulation.
• WebSocketProvider in web3.js v1.5.x maintains a persistent WebSocket connection and an internal EventEmitter for subscriptions such as newBlockHeaders. Subscription lifecycle is tied to provider instance lifetime.
• provider.disconnect() closes the socket and releases listeners for that provider instance. subscription.unsubscribe() removes the server-side subscription.

Likely explanation for the leak

In v1.5.x unsubscribe() removes the server-side subscription, but client-side emitter references can persist if the provider instance stays alive and subscriptions are recreated repeatedly without full cleanup. When components create newBlockHeaders subscriptions on mount and call unsubscribe on unmount without a central manager, orphaned emitter references can accumulate, producing incremental memory growth.

Steps needed for this case

1. Use one WebSocketProvider singleton for the process. Do not create a provider per component.
2. Create a single subscription manager that owns all newBlockHeaders subscriptions. Track subscription objects and ids centrally.
3. Subscribe once per logical need. On component unmount, call the stored subscription.unsubscribe() and remove the local listener via provider.removeListener or emitter.removeAllListeners for that handler. Do not recreate listeners on every mount.
4. Never call provider.disconnect() in the hot path. Disconnect only on process shutdown. Reconnect cost and event gaps outweigh any listener release benefit.
5. Monitor emitter.listenerCount for the relevant events and heap usage over cycles to verify cleanup.

HttpProvider remains the safe stateless choice when real-time push is not required. It avoids listener leaks by design at the cost of polling latency and higher request volume.

One diagnostic detail that changes the recommendation: confirm the exact web3.js minor version in use and whether components recreate subscription handlers on every mount without reusing the same subscription object. Behavior is version-specific to v1.5.x and does not generalize to later majors without verification.