Add a multiprocess mode to the object replicator. Setting the
"replicator_workers" setting to a positive value N will result in the
replicator using up to N worker processes to perform replication
tasks.
At most one worker per disk will be spawned, so one can set
replicator_workers=99999999 to always get one worker per disk
regardless of the number of disks in each node. This is the same
behavior that the object reconstructor has.
Worker process logs will have a bit of information prepended so
operators can tell which messages came from which worker. It looks
like this:
 [worker 1/2 pid=16529] 154/154 (100.00%) partitions replicated in 1.02s (150.87/sec, 0s remaining)
The prefix is "[worker M/N pid=P] ", where M is the worker's index, N
is the total number of workers, and P is the process ID. Every message
from the replicator's logger will have the prefix; this includes
messages from down in diskfile, but does not include things printed to
stdout or stderr.
Drive-by fix: don't dump recon stats when replicating only certain
policies. When running the object replicator with replicator_workers >
0 and "--policies=X,Y,Z", the replicator would update recon stats
after running. Since it only ran on a subset of objects, it should not
update recon, much like it doesn't update recon when run with
--devices or --partitions.
Change-Id: I6802a9ad9f1f9b9dafb99d8b095af0fdbf174dc5