Yeah because all the other exchanges are running perfect code.
If you're such the stud programmer and know all the trix offer to fix it for him, or PM him references to someone reputable that would do it for a modest fee. ..but no, both your answers have to be the most negative option possible.
He has a plan for recovery, and to continue on. He should do just that. His honesty in the face of a big crime is refreshing in the age of implausible deniability.
busoni, you need to shut down Poloniex now and try to make your users whole from your own funds and debt. Do not continue trying to run an exchange. Your post mortem indicates that you do not have sufficient programming ability to handle other peoples money - no mention was even made of database transactions, which are a basic "database programming 101" topic. Your proposed fix of checking for negative balances is wrong and indicates that your code is almost certainly riddled with other exploitable bugs.
Please do the right thing and refund everyones outstanding balances, then wind up your operation.
I agree with Mike. Attempting to patch this issue with something called a "negative balance watcher" is a
huge red flag.