better locking when pruning
better locking when pruning

replay/metrictank,OOM-Killer/metrictank,raintank/metrictank,replay/metrictank,OOM-Killer/metrictank,OOM-Killer/metrictank,replay/metrictank,raintank/metrictank,raintank/raintank-metric,raintank/raintank-metric,raintank/raintank-metric,raintank/metrictank,replay/metrictank,raintank/metrictank