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From "Michael Han (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (ZOOKEEPER-3098) Add additional server metrics
Date Mon, 17 Sep 2018 23:01:00 GMT

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-3098?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Michael Han resolved ZOOKEEPER-3098.
       Resolution: Fixed
    Fix Version/s: 3.6.0

Issue resolved by pull request 580

> Add additional server metrics
> -----------------------------
>                 Key: ZOOKEEPER-3098
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3098
>             Project: ZooKeeper
>          Issue Type: Improvement
>          Components: server
>    Affects Versions: 3.6.0
>            Reporter: Joseph Blomstedt
>            Assignee: Joseph Blomstedt
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 3.6.0
>          Time Spent: 5h 50m
>  Remaining Estimate: 0h
> This patch adds several new server-side metrics as well as makes it easier to add new
metrics in the future. This patch also includes a handful of other minor metrics-related changes.
> Here's a high-level summary of the changes.
>  # This patch extends the request latency tracked in {{ServerStats}} to track {{read}}
and {{update}} latency separately. Updates are any request that must be voted on and can change
data, reads are all requests that can be handled locally and don't change data.
>  # This patch adds the {{ServerMetrics}} logic and the related {{AvgMinMaxCounter}} and
{{SimpleCounter}} classes. This code is designed to make it incredibly easy to add new metrics.
To add a new metric you just add one line to {{ServerMetrics}} and then directly reference
that new metric anywhere in the code base. The {{ServerMetrics}} logic handles creating the
metric, properly adding the metric to the JSON output of the {{/monitor}} admin command, and
properly resetting the metric when necessary. The motivation behind {{ServerMetrics}} is to
make things easy enough that it encourages new metrics to be added liberally. Lack of in-depth
metrics/visibility is a long-standing ZooKeeper weakness. At Facebook, most of our internal
changes build on {{ServerMetrics}} and we have nearly 100 internal metrics at this time –
all of which we'll be upstreaming in the coming months as we publish more internal patches.
>  # This patch adds 20 new metrics, 14 which are handled by {{ServerMetrics}}.
>  # This patch replaces some uses of {{synchronized}} in {{ServerStats}} with atomic operations.
> Here's a list of new metrics added in this patch:
>  - {{uptime}}: time that a peer has been in a stable leading/following/observing state
>  - {{leader_uptime}}: uptime for peer in leading state
>  - {{global_sessions}}: count of global sessions
>  - {{local_sessions}}: count of local sessions
>  - {{quorum_size}}: configured ensemble size
>  - {{synced_observers}}: similar to existing `synced_followers` but for observers
>  - {{fsynctime}}: time to fsync transaction log (avg/min/max)
>  - {{snapshottime}}: time to write a snapshot (avg/min/max)
>  - {{dbinittime}}: time to reload database – read snapshot + apply transactions (avg/min/max)
>  - {{readlatency}}: read request latency (avg/min/max)
>  - {{updatelatency}}: update request latency (avg/min/max)
>  - {{propagation_latency}}: end-to-end latency for updates, from proposal on leader to
committed-to-datatree on a given host (avg/min/max)
>  - {{follower_sync_time}}: time for follower to sync with leader (avg/min/max)
>  - {{election_time}}: time between entering and leaving election (avg/min/max)
>  - {{looking_count}}: number of transitions into looking state
>  - {{diff_count}}: number of diff syncs performed
>  - {{snap_count}}: number of snap syncs performed
>  - {{commit_count}}: number of commits performed on leader
>  - {{connection_request_count}}: number of incoming client connection requests
>  - {{bytes_received_count}}: similar to existing `packets_received` but tracks bytes

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