The object reconstructor will now fork all available worker processes
when operating on a subset of local devices.
Example:
A system has 24 disks, named "d1" through "d24"
reconstructor_workers = 8
invoked with --override-devices=d1,d2,d3,d4,d5,d6
In this case, the reconstructor will now use 6 worker processes, one
per disk. The old behavior was to use 2 worker processes, one for d1,
d3, and d5 and the other for d2, d4, and d6 (because 24 / 8 = 3, so we
assigned 3 disks per worker before creating another).
I think the new behavior better matches operators' expectations. If I
give a concurrent program six tasks to do and tell it to operate on up
to eight at a time, I'd expect it to do all six tasks at once, not run
two concurrent batches of three tasks apiece.
This has no effect when --override-devices is not specified. When
operating on all local devices instead of a subset, the new and old
code produce the same result.
The reconstructor's behavior now matches the object replicator's
behavior.
Change-Id: Ib308c156c77b9b92541a12dd7e9b1a8ea8307a30
c4751d0d55