Mahmud Ridwan

I built Toph with Go, MongoDB, Redis, RabbitMQ, and S3-like object storage. The platform was built with scalability and resilience in mind. The code submitted by users is processed in a custom-built sandbox and in Go that uses Linux namespaces and cgroups to isolate the process and limit resources.

By May 2021, Toph already had 30,000 users, processed 700,000 submissions, and hosted 400+ programming contests, most of which were organized by 50+ academic institutions collaborating with Toph.

Redsync provides a Redis-based distributed mutual exclusion lock implementation for Go, as described in the following post: https://redis.io/topics/distlock.

The locking algorithm is safer than using a single instance of Redis.

Brdgd, pronounced "bridged," is a straightforward P2P file transfer web app. It depends on PeerJS to manage the P2P connections. The web app, in rare cases, uses a turn server to relay the connection in cases where the peers cannot reach each other due to certain obvious reasons.

Dots is a networking utility web application built with Node.js. It supports DNS (A, AAAA, CNAME, MX, among others), rDNS, WHOIS, and geolocation lookups on domains and IP addresses. It uses my WHOIS package for Node.js.

CodeMarshal is a programming contest hosting platform. It was built on Node.js and Python. The platform successfully hosted the preliminary mock, preliminary, and semi-live contests of the ACM ICPC 2013 Dhaka Regional.

Scanlib is a meta parser than can be used to validate text files. Scanlib is also able to emit C++, Go, and Python code that can read contents of similarly structured text files into variables.

This is useful in validating input files while designing programming challenges for competitive programming contests.

Arturia is a sandbox software and process orchestrator for Linux. It uses Linux namespaces, cgroups, and seccomp BPF to isolate resources from untrusted processes.

I wrote about Linux namespaces on the Toptal Engineering Blog: https://www.toptal.com/linux/separation-anxiety-isolating-your-system-with-linux-namespaces.