CodeWorld outage, now resolved

[Chris Smith]

We had a CodeWorld outage for a few hours this evening, from 7:45 pm to 11:17 pm, PST.  Sorry for any inconvenience this may have caused.  The outage prevented new code from being compiled, though all other functions remained in effect.

Details, in case you're curious:

Causes:

- Usage of CodeWorld has increased by about 50x starting Feb 27th.  Reason is unclear.

- The storage volume for compiled code exceeded its capacity at 7:45 this evening.

- Alerts did not fire; they were broken while increasing the size of the volume earlier in the week.

Solutions:

- Cleared the cache of compiled code, reducing volume usage to about 12% temporarily.

- Fixed the alert so that it will fire in the future.

In the near future, I will fix the problem by any/all of: resizing the disk to be substantially larger, compressing code on disk, or moving away from local disk for caching compiled code (https://github.com/google/codeworld/issues/84).

I don't know why there's suddenly about 50 times the steady state usage of CodeWorld.  That's great, if people are finding it useful!  But it's definitely got me curious.  Most of the traffic appears to be coming from Australia.