sizeOfMempool - Cardano

Example code for the sizeOfMempool WebSocket method. Complete guide on how to use sizeOfMempool WebSocket in GetBlock Web3 documentation.

This method returns the current size and capacity of the acquired mempool snapshot, including the number of transactions and the used and maximum byte and execution-unit budgets. This protocol requires a WebSocket connection.

Parameters

This method does not require parameters.

Request

JavaScript

example.js

import WebSocket from 'ws';

const client = new WebSocket('wss://go.getblock.io/<ACCESS-TOKEN>/');

client.once('open', () => {
    client.send(JSON.stringify({"jsonrpc": "2.0", "method": "sizeOfMempool", "id": "getblock.io"}));
});

client.on('message', (msg) => {
    console.log(JSON.parse(msg.toString()));
    client.close();
});

Python

example.py

import asyncio
import json
import websockets

async def main():
    async with websockets.connect('wss://go.getblock.io/<ACCESS-TOKEN>/') as ws:
        await ws.send(json.dumps({"jsonrpc": "2.0", "method": "sizeOfMempool", "id": "getblock.io"}))
        print(json.loads(await ws.recv()))

asyncio.run(main())

Response

{
    "jsonrpc": "2.0",
    "method": "sizeOfMempool",
    "result": {
        "maxCapacity": {
            "bytes": 4194304
        },
        "currentSize": {
            "bytes": 892014
        },
        "transactions": {
            "count": 43
        }
    },
    "id": "getblock.io"
}

Response Parameters

Field	Type	Description
maxCapacity	object	Maximum mempool capacity in bytes
currentSize	object	Current used size in bytes
transactions	object	Number of transactions in the snapshot

Use Cases

• Congestion Signals: Gauge how full the mempool is

• Backpressure: Delay submission when the mempool is near capacity

• Dashboards: Display mempool depth and capacity

• Capacity Planning: Track mempool pressure over time

Error Handling

Error Code	Message	Description
-32602	Invalid params	The request is malformed for the current protocol state
4000	Must acquire mempool	A snapshot must be acquired before this request
-32603	Internal error	The node failed to answer the mempool request