Add more pipeline processing stats

This adds the number of zk objects, nodes, and bytes read and written
during each pipeline processing run.  This can help Zuul developers
ascertain where to optimize performance.

Change-Id: Ic2592faeb08d6c2a72b99000864c41ada665cd3b

1 files changed, 36 insertions, 0 deletions

diff --git a/doc/source/monitoring.rst b/doc/source/monitoring.rst
index 3c0b2a1ff..10e358e49 100644
--- a/doc/source/monitoring.rst
+++ b/doc/source/monitoring.rst
@@ -235,6 +235,24 @@ These metrics are emitted by the Zuul :ref:`scheduler`:
          The time spent reading data from ZooKeeper during a single
          pipeline processing run.
 
+      .. stat:: read_znodes
+         :type: gauge
+
+         The number of ZNodes read from ZooKeeper during a single
+         pipeline processing run.
+
+      .. stat:: read_objects
+         :type: gauge
+
+         The number of Zuul data model objects read from ZooKeeper
+         during a single pipeline processing run.
+
+      .. stat:: read_bytes
+         :type: gauge
+
+         The amount of data read from ZooKeeper during a single
+         pipeline processing run.
+
       .. stat:: refresh
          :type: timer
 
@@ -273,6 +291,24 @@ These metrics are emitted by the Zuul :ref:`scheduler`:
          The time spent writing data to ZooKeeper during a single
          pipeline processing run.
 
+      .. stat:: write_znodes
+         :type: gauge
+
+         The number of ZNodes written to ZooKeeper during a single
+         pipeline processing run.
+
+      .. stat:: write_objects
+         :type: gauge
+
+         The number of Zuul data model objects written to ZooKeeper
+         during a single pipeline processing run.
+
+      .. stat:: write_bytes
+         :type: gauge
+
+         The amount of data written to ZooKeeper during a single
+         pipeline processing run.
+
 .. stat:: zuul.executor.<executor>
 
    Holds metrics emitted by individual executors.  The ``<executor>``