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Update write load monitor log-levels #136137

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Merged
merged 3 commits into from
Oct 8, 2025
Merged

Update write load monitor log-levels #136137

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5db5286
Update write load monitor log-levels
DiannaHohensee Oct 7, 2025
b5498c0
Merge branch 'main' into 2025/10/07/ES-13139-change-monitor-logging-l…
DiannaHohensee Oct 8, 2025
14661de
improve log message
DiannaHohensee Oct 8, 2025
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24 changes: 19 additions & 5 deletions ...rc/main/java/org/elasticsearch/cluster/routing/allocation/WriteLoadConstraintMonitor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.settings.ClusterSettings;
import org.elasticsearch.common.util.set.Sets;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.gateway.GatewayService;
import org.elasticsearch.threadpool.ThreadPool;

Expand Down Expand Up @@ -62,12 +63,12 @@ public WriteLoadConstraintMonitor(
public void onNewInfo(ClusterInfo clusterInfo) {
final ClusterState state = clusterStateSupplier.get();
if (state.blocks().hasGlobalBlock(GatewayService.STATE_NOT_RECOVERED_BLOCK)) {
logger.debug("skipping monitor as the cluster state is not recovered yet");
logger.trace("skipping monitor as the cluster state is not recovered yet");
return;
}

if (writeLoadConstraintSettings.getWriteLoadConstraintEnabled().notFullyEnabled()) {
logger.debug("skipping monitor because the write load decider is not fully enabled");
logger.trace("skipping monitor because the write load decider is not fully enabled");
return;
}

Expand All @@ -85,7 +86,7 @@ public void onNewInfo(ClusterInfo clusterInfo) {
});

if (nodeIdsExceedingLatencyThreshold.isEmpty()) {
logger.debug("No hot-spotting nodes detected");
logger.trace("No hot-spotting nodes detected");
return;
}

Expand All @@ -94,12 +95,22 @@ public void onNewInfo(ClusterInfo clusterInfo) {
final boolean haveCalledRerouteRecently = timeSinceLastRerouteMillis < writeLoadConstraintSettings.getMinimumRerouteInterval()
.millis();

// We know that there is at least one hot-spotting node if we've reached this code. Now check whether there are any new hot-spots
// or hot-spots that are persisting and need further balancing work.
if (haveCalledRerouteRecently == false
|| Sets.difference(nodeIdsExceedingLatencyThreshold, lastSetOfHotSpottedNodes).isEmpty() == false) {
if (logger.isDebugEnabled()) {
logger.debug(
"Found {} exceeding the write thread pool queue latency threshold ({} total), triggering reroute",
"""
Nodes [{}] are hot-spotting, of {} total cluster nodes. Reroute for hot-spotting {}. \
Previously hot-spotting nodes are [{}]. The write thread pool queue latency threshold is [{}]. Triggering reroute.
""",
nodeSummary(nodeIdsExceedingLatencyThreshold),
state.nodes().size(),
lastRerouteTimeMillis == 0
? "has never previously been called"
: "was last called [" + TimeValue.timeValueMillis(timeSinceLastRerouteMillis) + "] ago",
nodeSummary(lastSetOfHotSpottedNodes),
state.nodes().size()
);
}
Expand All @@ -115,7 +126,10 @@ public void onNewInfo(ClusterInfo clusterInfo) {
lastRerouteTimeMillis = currentTimeMillisSupplier.getAsLong();
lastSetOfHotSpottedNodes = nodeIdsExceedingLatencyThreshold;
} else {
logger.debug("Not calling reroute because we called reroute recently and there are no new hot spots");
logger.debug(
"Not calling reroute because we called reroute [{}] ago and there are no new hot spots",
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Suggested change
"Not calling reroute because we called reroute [{}] ago and there are no new hot spots",
"Not calling reroute because we called reroute [{}] ago or there are no new hot spots",

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I believe this is and. If either enough time passed or a new hot spot, then the if-statement triggers. So the else-statement is when time has not passed AND there are no new hot-spots.

I tried to make that a bit clearer with the new comment before the if-else statement, but seems still tricky.

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Err you are right.

TimeValue.timeValueMillis(timeSinceLastRerouteMillis)
);
}
}

Expand Down
16 changes: 8 additions & 8 deletions ...st/java/org/elasticsearch/cluster/routing/allocation/WriteLoadConstraintMonitorTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ public void testRerouteIsCalledWhenAHotSpotIsDetected() {
}

@TestLogging(
value = "org.elasticsearch.cluster.routing.allocation.WriteLoadConstraintMonitor:DEBUG",
value = "org.elasticsearch.cluster.routing.allocation.WriteLoadConstraintMonitor:TRACE",
reason = "ensure we're skipping reroute for the right reason"
)
public void testRerouteIsNotCalledWhenStateIsNotRecovered() {
Expand All @@ -81,7 +81,7 @@ public void testRerouteIsNotCalledWhenStateIsNotRecovered() {
new MockLog.SeenEventExpectation(
"don't reroute due to global block",
WriteLoadConstraintMonitor.class.getCanonicalName(),
Level.DEBUG,
Level.TRACE,
"skipping monitor as the cluster state is not recovered yet"
)
);
Expand All @@ -93,7 +93,7 @@ public void testRerouteIsNotCalledWhenStateIsNotRecovered() {
}

@TestLogging(
value = "org.elasticsearch.cluster.routing.allocation.WriteLoadConstraintMonitor:DEBUG",
value = "org.elasticsearch.cluster.routing.allocation.WriteLoadConstraintMonitor:TRACE",
reason = "ensure we're skipping reroute for the right reason"
)
public void testRerouteIsNotCalledWhenDeciderIsNotEnabled() {
Expand All @@ -117,7 +117,7 @@ public void testRerouteIsNotCalledWhenDeciderIsNotEnabled() {
new MockLog.SeenEventExpectation(
"don't reroute due to decider being disabled",
WriteLoadConstraintMonitor.class.getCanonicalName(),
Level.DEBUG,
Level.TRACE,
"skipping monitor because the write load decider is not fully enabled"
)
);
Expand All @@ -129,7 +129,7 @@ public void testRerouteIsNotCalledWhenDeciderIsNotEnabled() {
}

@TestLogging(
value = "org.elasticsearch.cluster.routing.allocation.WriteLoadConstraintMonitor:DEBUG",
value = "org.elasticsearch.cluster.routing.allocation.WriteLoadConstraintMonitor:TRACE",
reason = "ensure we're skipping reroute for the right reason"
)
public void testRerouteIsNotCalledWhenNoNodesAreHotSpotting() {
Expand All @@ -146,7 +146,7 @@ public void testRerouteIsNotCalledWhenNoNodesAreHotSpotting() {
new MockLog.SeenEventExpectation(
"don't reroute due to no nodes hot-spotting",
WriteLoadConstraintMonitor.class.getCanonicalName(),
Level.DEBUG,
Level.TRACE,
"No hot-spotting nodes detected"
)
);
Expand Down Expand Up @@ -196,7 +196,7 @@ public void testRerouteIsNotCalledAgainBeforeMinimumIntervalHasPassed() {
"don't reroute due to reroute being called recently",
WriteLoadConstraintMonitor.class.getCanonicalName(),
Level.DEBUG,
"Not calling reroute because we called reroute recently and there are no new hot spots"
"Not calling reroute because we called reroute * ago and there are no new hot spots"
)
);
writeLoadConstraintMonitor.onNewInfo(testState.clusterInfo);
Expand All @@ -213,7 +213,7 @@ public void testRerouteIsNotCalledAgainBeforeMinimumIntervalHasPassed() {
}

@TestLogging(
value = "org.elasticsearch.cluster.routing.allocation.WriteLoadConstraintMonitor:DEBUG",
value = "org.elasticsearch.cluster.routing.allocation.WriteLoadConstraintMonitor:TRACE",
reason = "ensure we're skipping reroute for the right reason"
)
public void testRerouteIsCalledBeforeMinimumIntervalHasPassedIfNewNodesBecomeHotSpotted() {
Expand Down