Well @vinay_2003 thank you for mentioning my name as this question and the 503 error is annoying me too. So i did a little checkup everywhere.The site respond time zaps every time one opens too many tabs of it . Also i found a question on quora about this answered by Anup Kalbalia ,Codechef organizing team,he said and i quote -
“503 should be Service Unavailable. It happens when there is a lot of load on the servers. Or also when there too many requests from the same IP. If you get this at any time other than at the start of the contest, it is likely that your request has hit a rate limiter.”…
Also then in comment he said-“Well I was clarifying the 503 is not an Internal Error. If you have seen a message of Internal Error with 503 status then we are worried. It will be helpful to send us a snapshot and you IP.
Coming to your question of scaling up, well it was an issue that we tried to fix today, and it got backfired. It was resolved when we re-started the contest. Hopefully things will be better now.”
so dont open too many tabs in once…or try this snapshot thing and if it works comment here so that i can do the same too…dont forget to tell me if you do it.