Memory leak on any query

[skokenes]

Running any query in duckdb-node leaks memory. Here is a simple test script that creates a connection and then runs a simple SELECT 42 AS fortytwo SQL statement every 100ms. The script also publishes memory usage to a file every minute. Memory never stops going up.

const duckdb = require("duckdb");
const fs = require("fs");

// Run simple duckdb query on repeat
const db = new duckdb.Database(":memory:");
const con = db.connect();
const stmt = con.prepare("SELECT 42 AS fortytwo");

function test() {
  stmt.all();
}
setInterval(test, 100);

// Capture memory stats over time and write to file
const path = "./data.csv";
fs.writeFileSync(path, "rss,heapTotal,heapUsed\n");
const stream = fs.createWriteStream(path, { flags: "a" });
setInterval(() => {
  const memory = process.memoryUsage();
  const rss = memory.rss / (1024 * 1024);
  const heapTotal = memory.heapTotal / (1024 * 1024);
  const heapUsed = memory.heapUsed / (1024 * 1024);
  console.log(`rss: ${rss} heapTotal: ${heapTotal} heapUsed: ${heapUsed}`);
  stream.write(`${rss},${heapTotal},${heapUsed}\n`);
}, 60000);

Here is a chart of the resulting memory stats, when run for 50 minutes on an MBP M2, node v18.18.2, duckdb 0.10.0

After 2 hours

EDIT: updated script to remove recursive call

[carlopi]

I believe we have a fix in #65, thanks a lot for the reproduction / investigation.

[rrcomtech]

I fear it is not fixed.

[carlopi]

@rrcomtech: can you share a reproduction / some more informations?

Any help in tracking problems down is very welcome

[rrcomtech]

@carlopi Sure, I reduced my code to a minimal example here: Memory Leak Demonstration

It creates 128 workers that create random data and send it to the main thread that puts it into DuckDB. It works fine with SQLite and PostgreSQL, but sadly I see the memory always increasing with DuckDB.