Database snapshot can be as large as 5GB. It is reasonable
to log before receiving it. Or the user might not know what
is happening and why etcd starts to use IO intensively.
The raft loop would block on the applier's done channel after
persisting the raft messages; the latency could cause dropped network
messages. Instead, asynchronously notify the applier with a buffered
channel when the raft writes complete.
raft's applyc writes block on the server loop's database IO since
the next applyc read must wait on the db operation to finish.
Instead, stream applyc to a run queue outside the server loop.
etcd might generate incomplete proxy config file after a power failure.
It is because we use ioutil.WriteFile. And iotuile.WriteFile does
not call Sync before closing the file.
deadlock if no leader; node selects on propc=nil and writes to Ready,
client blocks on propC in same select as Ready reader, and so progress
of raft state machine deadlocks.
For CoreOS users, they will get a updated version of etcdctl without updating
the etcd server version. And the users cannot really control this behavior.
We do not want to suddenly break them without enough communication.
So we still want the most basic opeartions like get, set, watch of etcdctl2 work
with etcd 0.4. This patches solve the incompability issue.
Mutex is a variable, which means there needs to be only one mutex
value per scope. We don't need a separate mutex inside store struct,
**if we assume that `TxnPut` and `TxnRange` are called ONLY ONCE
per transaction (between `TxnBegin` and `TxnEnd`)**, as documented.
Go 1.4 landed a new testing.M type [1][1] which allows for start-up and
shutdown hooks when running tests. The standard library now uses this
for checking for leaked goroutines in net/http [2][2].
This patch essentially re-ports the updated code from the net/http test
(we were using an older version of it) - in detail:
- updates the test to use `TestMain` instead of relying on
`TestGoroutinesRunning` to be implicitly run after all other tests
- adds a few new goroutines to the list of exceptions (the test itself,
as well as the golang/glog package and pkg/log.MergeLogger, both of
which spin off goroutines to handle log flushing/merging respectively)
- removes a couple of TODOs in the test for extra goroutines that's run
after individual tests (one of these re-enables the http package's
`.readLoop` and the other was an out-of-date TODO)
- re-enables the test
[1]: https://golang.org/pkg/testing/#M
[2]: https://github.com/golang/go/blob/release-branch.go1.4/src/net/http/main_test.go#L18
