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https://issues.apache.org/jira/browse/IGNITE-29222?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Egor Baranov updated IGNITE-29222:
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Description:
Add a new metric io.discovery.JoinedClientNodes that tracks the number of
client nodes that have joined the topology. The metric is registered in both
TcpDiscoveryStatistics and
ZookeeperDiscoveryStatistics, and is incremented on EVT_NODE_JOINED when
the joining node is a client.
was:
*Summary:* Add ClientsAddedToTopology monitoring metric to track client node
topology join events
h2.Problem Statement
Currently, Apache Ignite does not provide a built-in monitoring metric that
tracks the cumulative number of client nodes added to the cluster topology.
Operators who need to monitor client connection activity (e.g., for capacity
planning, detecting unexpected churn, or correlating application-level issues
with topology changes) must rely on log parsing of the
{code}GridDiscoveryManager{code} output, which is unreliable at scale and not
amenable to automated alerting.
h2.Proposed Solution
Introduce a new thread-safe counter metric, {code}ClientsAddedToTopology{code},
registered in the existing discovery metrics registry
({code}io.discovery{code}). The metric is incremented on each of the following
topology events:
# A new client node joins the topology ({code}EVT_NODE_JOINED{code} where the
joining node is a client).
# A disconnected client node reconnects to the topology
({code}EVT_CLIENT_NODE_RECONNECTED{code}).
The counter is implemented using {code}LongAdderMetric{code} (backed by
{code}java.util.concurrent.atomic.LongAdder{code}), ensuring lock-free,
thread-independent increments even under high-frequency client
connection/disconnection workloads.
h2.Metric Details
{table}
|*Property*|*Value*
|Registry|{code}io.discovery{code}
|Metric Name|{code}ClientsAddedToTopology{code}
|Type|Long (counter, monotonically increasing)
|Description|Count of client nodes added to topology
|JMX Access|Via {code}JmxMetricExporterSpi{code} (default)
{table}
h2.Acceptance Criteria
# The metric is exposed via the standard Ignite metrics API
({code}Ignite.context().metric().registry("io.discovery"){code}).
# The metric is accessible via JMX (MBean) without additional configuration.
# The counter is thread-safe and does not introduce measurable contention under
concurrent client join/reconnect events.
# Unit tests verify:
## The metric starts at 0 on a fresh node.
## The metric increments by 1 per client node join.
## The metric name and description are correctly registered.
# The test class is registered in the {code}IgniteKernalSelfTestSuite{code}.
# The implementation follows the existing project style and conventions for
metric registration.
h2.Affected Components
# {code}GridDiscoveryManager{code} (core) — metric initialization and increment
logic
# {code}IgniteKernalSelfTestSuite{code} (test) — new test class registration
# {code}GridDiscoveryManagerClientMetricTest{code} (test) — new test class
h2.Performance Impact
None. The counter uses {code}LongAdder{code} which provides O(1) amortized
increments with no global lock. The metric is created during node startup and
adds one additional entry to the existing {code}io.discovery{code} metric
registry.
> Add ClientsAddedToTopology monitoring metric to track client node topology
> join events
> --------------------------------------------------------------------------------------
>
> Key: IGNITE-29222
> URL: https://issues.apache.org/jira/browse/IGNITE-29222
> Project: Ignite
> Issue Type: New Feature
> Affects Versions: 2.19
> Reporter: Egor Baranov
> Assignee: Egor Baranov
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Add a new metric io.discovery.JoinedClientNodes that tracks the number of
> client nodes that have joined the topology. The metric is registered in both
> TcpDiscoveryStatistics and
> ZookeeperDiscoveryStatistics, and is incremented on EVT_NODE_JOINED when
> the joining node is a client.
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