Hello wonderful relay operators,
I wanted to let you know about a bug that might affect you if you use the AccountingMax option, in Tor 0.4.0 and later. Here's the ChangeLog entry from the upcoming 0.4.2.3-alpha:
o Major bugfixes (relay): - Relays now respect their AccountingMax bandwidth again. When relays entered "soft" hibernation (which typically starts when we've hit 90% of our AccountingMax), we had stopped checking whether we should enter hard hibernation. Soft hibernation refuses new connections and new circuits, but the existing circuits can continue, meaning that relays could have exceeded their configured AccountingMax. Fixes bug 32108; bugfix on 0.4.0.1-alpha.
That is, when your relay enters "soft" hibernation, you stop accepting new connections and new circuits (good), but you stop checking whether you've hit the hard limit and need to close down the remaining circuits (bad).
The bug has the additional impact that when your Tor has entered soft hibernation, it stops updating the 'state' file in its DataDirectory, which means it doesn't record new bytes spent in the interval after that point.
You can read more details on the trac ticket: https://bugs.torproject.org/32108
We'll have an 0.4.2.3-alpha release out soon with what we hope is a fix. And if it looks good then we'll plan to put out new 0.4.0.6 and 0.4.1.7 stables.
In the meantime, if this bug affects you, you might do some combination of the following:
* Watch your relay's bandwidth use and logs more carefully than usual
* Downgrade to Tor 0.3.5.8 until the newer stables are ready
* Set your RelayBandwidthRate to a lower value so you don't hit soft hibernation as quickly during this interval
* Apply the two-line patch yourself (and let us know whether anything breaks)
Sorry for the troubles, --Roger