Concurrency count is not updated immediately after closing a sandbox.

[jamesmurdza]

Describe the bug When closing and creating sandboxes quickly, the concurrency limit will be reached, the count is not updated right away.

To Reproduce

import { Sandbox } from "@e2b/sdk";
import { config } from "dotenv";
config();

// Map over an array with a fixed number of threads
// https://stackoverflow.com/a/71239408/8784402
const asyncMap = async <T, Q>(
  x: T[],
  threads: number,
  fn: (v: T, i: number, a: T[]) => Promise<Q>
) => {
  let k = 0;
  const result = Array(x.length) as Q[];
  await Promise.all(
    [...Array(threads)].map(async () => {
      while (k < x.length) result[k] = await fn(x[k], k++, x);
    })
  );
  return result;
};

// Run a given number of sandboxes concurrently
async function runTasks(count: number, concurrency: number) {
  let concurrentTasks = 0;
  await asyncMap(Array(count), concurrency, async () => {
    concurrentTasks++;
    console.log(`Number of running tasks: ${concurrentTasks}`);
    let sandbox = await Sandbox.create();
    await sandbox.close();
    concurrentTasks--;
  });
}

runTasks(40, 15);

Expected behavior This should not give an error, because only 15 sandboxes are run concurrently.

Terminal commands & output

Number of running tasks: 1
Number of running tasks: 2
Number of running tasks: 3
Number of running tasks: 4
Number of running tasks: 5
Number of running tasks: 6
Number of running tasks: 7
Number of running tasks: 8
Number of running tasks: 9
Number of running tasks: 10
Number of running tasks: 11
Number of running tasks: 12
Number of running tasks: 13
Number of running tasks: 14
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
Number of running tasks: 15
/Users/james/code/project/node_modules/openapi-typescript-fetch/dist/cjs/fetcher.js:6
        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
                                                                ^
ApiError: Forbidden
    at /Users/james/code/project/node_modules/openapi-typescript-fetch/dist/cjs/fetcher.js:154:23
    at Generator.throw (<anonymous>)
    at rejected (/Users/james/code/project/node_modules/openapi-typescript-fetch/dist/cjs/fetcher.js:6:65)
    at processTicksAndRejections (node:internal/process/task_queues:95:5) {
  headers: Headers {
    [Symbol(headers list)]: HeadersList {
      cookies: null,
      [Symbol(headers map)]: [Map],
      [Symbol(headers map sorted)]: null
    },
    [Symbol(guard)]: 'immutable',
    [Symbol(realm)]: null
  },
  url: 'https://api.e2b.dev/instances',
  status: 403,
  statusText: 'Forbidden',
  data: {
    code: 403,
    message: "You have reached the maximum number of concurrent sandboxes (20). If you need more, please contact us at 'https://e2b.dev/docs/getting-help'"
  }
}

[linear[bot]]

E2B-462 Concurrency count is not updated immediately after closing a sandbox.

[jamesmurdza]

Also, adding a delay after sandbox.close helps, but only a long one. For this example, ten seconds seems to work.

[mlejva]

Thank you for submitting the issue @jamesmurdza, this looks like a bug related to the fact that when you call sandbox.close() we internally keep the sandbox running for 15 seconds to finish any I/O (especially if any logs need to be send to the client).

I think we'll need to rethink how we're handling the close() process.

[jamesmurdza]

Agreed. For now, I’ll have to add a delay of 15 seconds before starting the next task.

[jamesmurdza]

How we're handling this currently:

Code: https://github.com/gitwitorg/react-eval/commit/f2fb246d692b1c402258e913d9403c138f445521

[mlejva]

Hey @jamesmurdza, we have an experimental stateless SDK in the works that has a kill method https://github.com/e2b-dev/E2B/pull/313

It’s stateless in a sense that you don’t need to manage Sandbox’s lifecycle in your code. Would love to learn if it would be helpful to you and any other feedback.

[ValentaTomas]

The .close() method is removed in the new beta SDK (https://e2b.dev/docs/guide/beta-migration). After the sandbox expires or when you call .kill() the concurrency count should be updated almost immediately.