water.telemetry

Class JvmTelemetry

java.lang.Object

water.telemetry.JvmTelemetry

public class JvmTelemetry
extends java.lang.Object

Fire-and-forget JVM-side telemetry. Emits a single cluster_started event (with client="jvm") once the cluster has formed (Paxos common knowledge) and its node count has settled. This is the server-side counterpart to the clients' init event. It makes standalone java -jar h2o.jar and hadoop jar h2odriver.jar clusters — which no Python/R client ever attaches to — visible to telemetry. Design constraints:

• Leader-only: only H2O.CLOUD.leader() emits, so an N-node cluster produces exactly one event, not N.
• Fires post cloud-lock: waits for Paxos._commonKnowledge ("Cloud of size N formed"), then waits for the size to stabilize so a staggered multi-node / YARN launch reports its final node count.
• Never blocks or throws: runs on a daemon thread, swallows every exception, hard-caps every wait. Startup and shutdown are never delayed.
• Java 8 compatible: plain HttpURLConnection, no Java 11+ API.
• Opt-in by default-off: telemetry stays off unless it is explicitly enabled by setting the disable flag to false — -Dsys.ai.h2o.telemetry.disabled=false. The DO_NOT_TRACK env var (reacts to 1/0/true/false) and -Dsys.ai.h2o.telemetry.disabled=true force it off. These switches flip isEnabled() / the status row.
• No double-count: a Python/R-spawned local server sets -Dsys.ai.h2o.telemetry.clientLaunched=true; the calling client already reports that session, so the spawned JVM skips its cluster_started. This is dedup, not an opt-out — telemetry stays enabled.

Wire shape mirrors the Python/R clients byte-for-byte (buckets, field names).

Constructor Summary

Constructors

Constructor and Description
JvmTelemetry()

Method Summary

Modifier and Type	Method and Description
static boolean	isEnabled() Whether telemetry would currently emit on this JVM — the inverse of disabled().
static void	scheduleInitEmit() Spawn a daemon thread that waits for cloud formation and then emits one cluster_started event from the leader.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JvmTelemetry

public JvmTelemetry()

Method Detail

scheduleInitEmit

public static void scheduleInitEmit()

Spawn a daemon thread that waits for cloud formation and then emits one cluster_started event from the leader. No-op when telemetry is opted out. Safe to call from any startup path; only the leader actually emits.

isEnabled

public static boolean isEnabled()

Whether telemetry would currently emit on this JVM — the inverse of disabled(). Surfaced on CloudV3.telemetry_enabled so clients can show the server's state.