document metrics changes

CHANGES.rst

@@ -2,7 +2,10 @@ Unreleased
 ==========
 
 synctl no longer starts the main synapse when using ``-a`` option with workers.
-A new worker file should be added with ``worker_app: synapse.app.homeserver``
+A new worker file should be added with ``worker_app: synapse.app.homeserver``.
+
+This release also begins the process of renaming a number of the metrics
+reported to prometheus. See `docs/metrics-howto.rst <docs/metrics-howto.rst#block-and-response-metrics-renamed-for-0-27-0>`_.
 
 
 Changes in synapse v0.26.0 (2018-01-05)

docs/metrics-howto.rst

@@ -33,6 +33,53 @@ How to monitor Synapse metrics using Prometheus
 
    Restart prometheus.
 
+
+Block and response metrics renamed for 0.27.0
+---------------------------------------------
+
+Synapse 0.27.0 begins the process of rationalising the duplicate ``*:count``
+metrics reported for the resource tracking for code blocks and HTTP requests.
+
+At the same time, the corresponding ``*:total`` metrics are being renamed, as
+the ``:total`` suffix no longer makes sense in the absence of a corresponding
+``:count`` metric.
+
+To enable a graceful migration path, this release just adds new names for the
+metrics being renamed. A future release will remove the old ones.
+
+The following table shows the new metrics, and the old metrics which they are
+replacing.
+
+==================================================== ===================================================
+New name                                             Old name
+==================================================== ===================================================
+synapse_util_metrics_block_count                     synapse_util_metrics_block_timer:count
+synapse_util_metrics_block_count                     synapse_util_metrics_block_ru_utime:count
+synapse_util_metrics_block_count                     synapse_util_metrics_block_ru_stime:count
+synapse_util_metrics_block_count                     synapse_util_metrics_block_db_txn_count:count
+synapse_util_metrics_block_count                     synapse_util_metrics_block_db_txn_duration:count
+
+synapse_util_metrics_block_time_seconds              synapse_util_metrics_block_timer:total
+synapse_util_metrics_block_ru_utime_seconds          synapse_util_metrics_block_ru_utime:total
+synapse_util_metrics_block_ru_stime_seconds          synapse_util_metrics_block_ru_stime:total
+synapse_util_metrics_block_db_txn_count              synapse_util_metrics_block_db_txn_count:total
+synapse_util_metrics_block_db_txn_duration_seconds   synapse_util_metrics_block_db_txn_duration:total
+
+synapse_http_server_response_count                   synapse_http_server_requests
+synapse_http_server_response_count                   synapse_http_server_response_time:count
+synapse_http_server_response_count                   synapse_http_server_response_ru_utime:count
+synapse_http_server_response_count                   synapse_http_server_response_ru_stime:count
+synapse_http_server_response_count                   synapse_http_server_response_db_txn_count:count
+synapse_http_server_response_count                   synapse_http_server_response_db_txn_duration:count
+
+synapse_http_server_response_time_seconds            synapse_http_server_response_time:total
+synapse_http_server_response_ru_utime_seconds        synapse_http_server_response_ru_utime:total
+synapse_http_server_response_ru_stime_seconds        synapse_http_server_response_ru_stime:total
+synapse_http_server_response_db_txn_count            synapse_http_server_response_db_txn_count:total
+synapse_http_server_response_db_txn_duration_seconds synapse_http_server_response_db_txn_duration:total
+==================================================== ===================================================
+
+
 Standard Metric Names
 ---------------------
 
@@ -42,7 +89,7 @@ have been changed to seconds, from miliseconds.
 
 ================================== =============================
 New name                           Old name
----------------------------------- -----------------------------
+================================== =============================
 process_cpu_user_seconds_total     process_resource_utime / 1000
 process_cpu_system_seconds_total   process_resource_stime / 1000
 process_open_fds (no 'type' label) process_fds
@@ -52,7 +99,7 @@ The python-specific counts of garbage collector performance have been renamed.
 
 =========================== ======================
 New name                    Old name
---------------------------- ----------------------
+=========================== ======================
 python_gc_time              reactor_gc_time
 python_gc_unreachable_total reactor_gc_unreachable
 python_gc_counts            reactor_gc_counts
@@ -62,7 +109,7 @@ The twisted-specific reactor metrics have been renamed.
 
 ==================================== =====================
 New name                             Old name
------------------------------------- ---------------------
+==================================== =====================
 python_twisted_reactor_pending_calls reactor_pending_calls
 python_twisted_reactor_tick_time     reactor_tick_time
 ==================================== =====================