If the limit is less than the ideal, try to increase it to the ideal.
If that doesn't work, try to increase the limit as high as possible.
If the limit is still less than the minimum, panic.
Some systems have a very small /dev/shm, for example, see:
https://github.com/docker-library/postgres/issues/416
So we should just use the temporary directory on all operating systems.
Also:
* use TempDir to generate the temporary path
* delete the code that we copied from sled
* prefix the temporary path with the state version and network
## Motivation
Prior to this PR we've been using `sled` as our database for storing persistent chain data on the disk between boots. We picked sled over rocksdb to minimize our c++ dependencies despite it being a less mature codebase. The theory was if it worked well enough we'd prefer to have a pure rust codebase, but if we ever ran into problems we knew we could easily swap it out with rocksdb.
Well, we ran into problems. Sled's memory usage was particularly high, and it seemed to be leaking memory. On top of all that, the performance for writes was pretty poor, causing us to become bottle-necked on sled instead of the network.
## Solution
This PR replaces `sled` with `rocksdb`. We've seen a 10x improvement in memory usage out of the box, no more leaking, and much better write performance. With this change writing chain data to disk is no longer a limiting factor in how quickly we can sync the chain.
The code in this pull request has:
- [x] Documentation Comments
- [x] Unit Tests and Property Tests
## Review
@hdevalence
Closes#1026
Because of the way that sled uses this parameter, the actual in-memory
size may be much larger. Dialing this down should help avoid high
memory usage.
* Run large checkpoint sync tests in CI
* Improve test child output match error context
* Add a debug_stop_at_height config
* Use stop at height in acceptance tests
And add some restart acceptance tests, to make sure the stop at
height feature works correctly.
teor
Jane Lusby
Henry de Valence
Jane Lusby