* test(weed/topology): benchmark the per-heartbeat volume sync
A volume server re-sends its entire volume list every VolumePulsePeriod, so
SyncDataNodeRegistration is the master's steady-state per-server cost. Give it
a benchmark so allocation regressions show up.
* perf(weed/topology): preallocate the heartbeat volume conversion slice
The slice grows to one entry per volume on the data node, so at 100k volumes
the doubling copies allocate 60MB of garbage per heartbeat. The final length is
known up front.
BenchmarkSyncDataNodeRegistration/100000Volumes 199670102 B/op -> 137725872 B/op
Chris Lu
3fce1a938d