Evalda's claim to being "battle-tested" isn't a vibe — it's two production events, both run against a live clock with no retry window, both finished with the leaderboard standing. This page is the receipts.
Evalda's first outing, judging the annual data science competition of the DataOverflow event.
| Metric | Value |
|---|---|
| Duration | 7 continuous hours |
| Participants | 164 across 41 teams |
| Total submissions | 1,452 (435 accepted, 1,017 rejected) |
| Peak throughput | 400 submissions in one hour |
| DDoS attacks absorbed | 3 |
| Total downtime | < 1 minute (two config-only maintenance windows) |
The lessons from this event (the preprocess() latency bypass, the trust-boundary redesign, the pre-event penetration audit) are written up honestly in architecture.md — Known Limitations and Lessons Learned.
The second deployment ran both tracks simultaneously through an overnight event (21:00 → 05:00 UTC) — the data science track judging file submissions while the MLOps track provisioned and graded live cloud VMs.
| Metric | Value |
|---|---|
| Submissions | 349 (253 accepted, 96 rejected) |
| Teams | 16 active of 27 registered, 61 users |
| Peak hour | 67 submissions |
| Peak 10 minutes | 18 submissions (at 4:50 AM, naturally) |
| Best accuracy reached | 95.5% |
| Downtime | 0 |
Submission pressure never let up — the hourly histogram is essentially flat from 1 AM to 5 AM (67, 64, 57, 66), meaning the judging pipeline ran at a sustained load all night rather than surviving one spike.
| Metric | Value |
|---|---|
| Grade runs | 92 (64 graded, 28 rejected by the grader's gates) |
| VMs provisioned | 15, across 2 AWS accounts (9 + 6) |
| Provisioning failures | 0 |
| Orphaned VMs after the event | 0 (every VM reached terminated) |
| Challenges | 3, opened sequentially (2h / 3h / 3h windows) |
| Teams | 5 active of 7 registered |
Every one of the three challenges was fully cracked — at least one team hit the maximum score of 1000 on each. The 28 non-graded runs were the grader's gates doing their job (VM unreachable, correctness gate failed, reset contract broken), not platform errors: each returned a precise verdict to the team instead of a silent failure.
Across both events: ~1,800 submissions, 48 active teams, 15 hours of live competition, zero unplanned downtime.
One footnote for the readers who made it this far. At 4 AM the night before the event, a sanity call to Ossama Ferjani ended with a sentence you never want to hear at that hour: "You know free-trial AWS accounts cap your concurrent vCPUs, right?" With every team's VM running at once, the event needed more vCPUs than the account was allowed to have.
So the single-account provisioning layer became a multi-account load balancer overnight: a borrowed second account, a per-account vCPU budget in the atomic slot claim, per-account credentials and networks in Terraform, account-aware watchers and teardown. (The backend itself sat on an m6i.2xlarge in a separate paid account, unbothered.) Hours later it placed 15 VMs across the two accounts with zero failures.
Lesson: quotas are architecture — and the best pre-event engineering tool is a friend who's been burned before you.