Reduce memory usage

[ringsaturn]

• The DefaultFinder will not use probuf timezone data, so just not save it when necessary
• After NewFinder from bin data, the allocs/heap will increase to a large number, but after GC, heap will reduce to far less. Maybe it’s possible to use sync.Pool to reduce init memory usage.

TODO

• Not save probuf timezone in memory for DefaultFinder add finder opt to reduce mem when not need #60
• Add sync.Pool for init

[ringsaturn]

2022-11-12 update

Using sync.Pool seems not work since most memory cost came from Unmarshall bytes from tzf-rel’s large bytes var.

Need check other data formats which don’t require load all data to memory at 1 time when unmarshall, or change the init way with a for loop over lots smaller bytes to use sync.Poll

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#64 will force run GC after init, at least memory seems smaller than before, but still require 150MB for init.