Locks

Shaken Fist uses etcd for distributed locking. All locks are written into etcd with the /sflocks key prefix. Locks are effectively leases on a key within etcd, where the key contains metadata about the lock being held. This means its easy to determine who else is holding a lock if you see contention issues within your cluster.

The easiest way to do this is with the sf-client admin lock list command, which will list all locks currently held in the cluster. For example, here's a relatively idle cluster:

$ sf-client admin lock list
+----------------------+-------+------+---------------------+
|         lock         |  pid  | node |      operation      |
+----------------------+-------+------+---------------------+
| /sflocks/sf/cluster/ | 26407 | sf-7 | Cluster maintenance |
+----------------------+-------+------+---------------------+