Improve safety for weed shells `ec.encode`.
The current process for `ec.encode` is:
1. EC shards for a volume are generated and added to a single server
2. The original volume is deleted
3. EC shards get re-balanced across the entire topology
It is then possible to lose data between #2 and #3, if the underlying volume storage/server/rack/DC
happens to fail, for whatever reason. As a fix, this MR reworks `ec.encode` so:
* Newly created EC shards are spread across all locations for the source volume.
* Source volumes are deleted only after EC shards are converted and balanced.
Improve parallelization for `ec.encode`.
Instead of processing one volume at at time, perform all EC conversion
steps (mark readonly -> generate EC shards -> delete volume -> remount) in
parallel for all of them.
This should substantially improve performance when EC encoding
entire collections.
* Don't ignore empty (`""`) collection names when computing collections for a given volume ID.
* `ec.encode`: Fix resolution of target collections.
When no `volumeId` parameter is provided, compute volumes
based on the provided collection name, even if it's empty (`""`).
This restores behavior to before recent EC rebalancing rework. See also
ec30a504ba/weed/shell/command_ec_encode.go (L99) .
This logic was originally part of `spreadEcShards()`, which got removed during
the unification effort with `ec.balance` (https://github.com/seaweedfs/seaweedfs/pull/6344),
accidentally breaking functionality in the process.
The commit restores the deletion code for EC'd volumes - with parallelization support.
* Begin implementing EC balancing parallelization support.
Impacts both `ec.encode` and `ec.balance`,
* Nit: improve type naming.
* Make the goroutine workgroup handler for `EcBalance()` a bit smarter/error-proof.
* Nit: unify naming for `ecBalancer` wait group methods with the rest of the module.
* Fix concurrency bug.
* Fix whitespace after Gitlab automerge.
* Delete stray TODO.
Lisandro Pin
Chris Lu
wyang
chrislu
Max Denushev
NyaMisty
Konstantin Lebedev
chrislu