And if stuff doesn't get written in Go, then people will criticise Go for not having anything in production. The internet is not going to run out of space through people writing too much software.
groupcache has a couple of differences from memcached that are probably part of why it exists:
- thundering herds suck, so it manages how the cache is filled when a key is missing
- repeatedly retrieving super hot values will eventually exhaust the network pipe of whichever server held, so groupcache replicates hot values to more than one cache server
Since this was built for dl.google.com, the 'value' might be big (say, a chunk of the Chrome binary) and the request rates for the top cache keys probably get pretty high. So, even if memcached is doing good work for lots of folks, the distinct features of groupcache probably address real needs in the app.
And, yeah, groupcache and the dl.google.com rewrite are Go partly because Brad likes Go, but both projects had reasons to exist quite apart from deploying Go for Go's sake.
