FailoverHeartbeatTTL is the amount of time to wait after a server leader failure
before considering reallocating client tasks. This TTL should be fairly long as
the new server leader needs to rebuild the entire heartbeat map for the
cluster. In deployments with a small number of machines, the default TTL (5m)
may be unnecessary long. Let's allow operators to configure this value in their
config files.
Suppress stats streaming error log messages when task finishes.
Streaming errors are expected when a task finishes and they aren't
actionable to users.
Also, note that the task runner Stats hook retries collecting stats
after a delay. If the connection terminates prematurely, it will be
retried, and closing the stats stream is not very disruptive.
Ideally, executor terminates cleanly when task exits, but that's a more
substantial change that may require changing the executor/drivers interface.
Fixes#10814
Fix a logmon leak causing high goroutine and memory usage when a task
restarts.
Logmon `FileRotator` buffers the task stdout/stderr streams and
periodically flushing them to log files. Logmon creates a new
FileRotator for each stream for each task run. However, the
`flushPeriodically` goroutine is leaked when a task restarts,
holding a reference to a no-longer-needed `FileRotator` instance
along with its 64kb buffer.
The cause is that the code assumed `time.Ticker.Stop()` closes the
ticker channel, thereby terminating the goroutine, but the documentation
says otherwise:
> Stop turns off a ticker. After Stop, no more ticks will be sent. Stop does not close the channel, to prevent a concurrent goroutine reading from the channel from seeing an erroneous "tick".
https://pkg.go.dev/time#Ticker.Stop
The fix seems to be related to the pointer comparison and swapping we
did around killing a non-leader. I actually can't quite explain it, but
when comparing against Consul's version of this test I noticed they used
the slice index to track the killed server instead of pointer swapping.
As soon as I switched to slice index tracking I could no longer
reproduce the failure.
In addition:
- Tested membership counts on all servers instead of just 1 for added
correctness.
- Stopped testing raft v1 because it is unsupported.
