utafrali commented on code in PR #3852:
URL: https://github.com/apache/celeborn/pull/3852#discussion_r4033459834
##########
service/src/main/scala/org/apache/celeborn/common/metrics/sink/PrometheusServlet.scala:
##########
@@ -37,4 +37,23 @@ class PrometheusServlet(
servletPath,
new ServletParams(_ => getMetricsSnapshot, "text/plain"))
}
+
+ override def getMetricsSnapshot: String = {
+ val raw = super.getMetricsSnapshot
+ val seen = scala.collection.mutable.HashSet[String]()
+ val header = "^#\\s+(TYPE|HELP)\\s+(\\S+)\\b.*$".r
Review Comment:
The regex is compiled fresh on every call to `getMetricsSnapshot`. Under
high scrape frequency this adds unnecessary overhead. Move it to the companion
object:
```scala
object PrometheusServlet {
private val headerLine = "^#\\s+(TYPE|HELP)\\s+(\\S+)\\b.*$".r
}
```
Then reference it as `PrometheusServlet.headerLine` (or just `headerLine`)
inside the class.
##########
service/src/test/scala/org/apache/celeborn/common/metrics/sink/PrometheusServletSuite.scala:
##########
@@ -0,0 +1,69 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.celeborn.common.metrics.sink
+
+import java.util.Properties
+
+import com.codahale.metrics.MetricRegistry
+
+import org.apache.celeborn.CelebornFunSuite
+import org.apache.celeborn.common.CelebornConf
+import org.apache.celeborn.common.metrics.source.{AbstractSource, Role}
+
+class PrometheusServletSuite extends CelebornFunSuite {
+
+ private def newServlet(source: AbstractSource): PrometheusServlet = {
+ new PrometheusServlet(
+ new Properties(),
+ new MetricRegistry(),
+ Seq(source),
+ "/metrics/prometheus")
+ }
+
+ test("getMetricsSnapshot deduplicates # HELP and # TYPE lines per metric
family") {
+ val conf = new CelebornConf()
+ val source = new AbstractSource(conf, Role.WORKER) {
+ override def sourceName: String = "mockSource"
+ }
+
+ val user1 = Map("user" -> "user1")
+ val user2 = Map("user" -> "user2")
+ source.addCounter("Counter", user1)
+ source.addCounter("Counter", user2)
+ source.incCounter("Counter", 1, user1)
+ source.incCounter("Counter", 2, user2)
+
+ source.addGauge("Gauge1") { () => 1000 }
+
+ val snapshot = newServlet(source).getMetricsSnapshot
+ val lines = scala.io.Source.fromString(snapshot).getLines().toList
+
+ val counterName = "metrics_Counter_Count"
+ val gaugeName = "metrics_Gauge1_Value"
+
+ assert(lines.count(_ == s"# HELP $counterName") == 1)
+ assert(lines.count(_ == s"# TYPE $counterName counter") == 1)
+ assert(lines.exists(_ == s"# TYPE $counterName counter"))
Review Comment:
This assertion is redundant. Line 60 already verifies `count == 1`, which
implies `exists` is true. Remove line 61:
```scala
// remove: assert(lines.exists(_ == s"# TYPE $counterName counter"))
```
##########
service/src/test/scala/org/apache/celeborn/common/metrics/sink/PrometheusServletSuite.scala:
##########
@@ -0,0 +1,69 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.celeborn.common.metrics.sink
+
+import java.util.Properties
+
+import com.codahale.metrics.MetricRegistry
+
+import org.apache.celeborn.CelebornFunSuite
+import org.apache.celeborn.common.CelebornConf
+import org.apache.celeborn.common.metrics.source.{AbstractSource, Role}
+
+class PrometheusServletSuite extends CelebornFunSuite {
+
+ private def newServlet(source: AbstractSource): PrometheusServlet = {
+ new PrometheusServlet(
+ new Properties(),
+ new MetricRegistry(),
+ Seq(source),
+ "/metrics/prometheus")
+ }
+
+ test("getMetricsSnapshot deduplicates # HELP and # TYPE lines per metric
family") {
+ val conf = new CelebornConf()
+ val source = new AbstractSource(conf, Role.WORKER) {
+ override def sourceName: String = "mockSource"
+ }
+
+ val user1 = Map("user" -> "user1")
+ val user2 = Map("user" -> "user2")
+ source.addCounter("Counter", user1)
+ source.addCounter("Counter", user2)
+ source.incCounter("Counter", 1, user1)
+ source.incCounter("Counter", 2, user2)
+
+ source.addGauge("Gauge1") { () => 1000 }
+
+ val snapshot = newServlet(source).getMetricsSnapshot
+ val lines = scala.io.Source.fromString(snapshot).getLines().toList
+
+ val counterName = "metrics_Counter_Count"
+ val gaugeName = "metrics_Gauge1_Value"
+
+ assert(lines.count(_ == s"# HELP $counterName") == 1)
+ assert(lines.count(_ == s"# TYPE $counterName counter") == 1)
+ assert(lines.exists(_ == s"# TYPE $counterName counter"))
+ assert(lines.count(_.startsWith(s"$counterName{")) == 2)
+ assert(snapshot.contains("""user="user1""""))
+ assert(snapshot.contains("""user="user2""""))
+ assert(lines.count(_ == s"# HELP $gaugeName") == 1)
+ assert(lines.count(_ == s"# TYPE $gaugeName gauge") == 1)
+ assert(lines.exists(_.startsWith(s"$gaugeName")) &&
snapshot.contains("1000"))
Review Comment:
The gauge sample assertion is weaker than the counter assertions. The test
verifies that a line starting with `gaugeName` exists and that `"1000"` appears
somewhere in the snapshot, but it does not verify there is exactly one sample
line for the gauge. For consistency with the counter checks above, prefer:
```scala
assert(lines.count(_.startsWith(s"$gaugeName")) == 1)
assert(lines.exists(_.contains("1000")))
```
##########
service/src/main/scala/org/apache/celeborn/common/metrics/sink/PrometheusServlet.scala:
##########
@@ -37,4 +37,23 @@ class PrometheusServlet(
servletPath,
new ServletParams(_ => getMetricsSnapshot, "text/plain"))
}
+
+ override def getMetricsSnapshot: String = {
+ val raw = super.getMetricsSnapshot
+ val seen = scala.collection.mutable.HashSet[String]()
+ val header = "^#\\s+(TYPE|HELP)\\s+(\\S+)\\b.*$".r
+ val out = new StringBuilder(raw.length)
+
+ scala.io.Source.fromString(raw).getLines().foreach {
Review Comment:
`scala.io.Source.fromString(raw).getLines()` is a roundabout way to iterate
over the lines of an in-memory string. It wraps a `StringReader` inside a
`BufferedSource` and is not closed here (no `finally` / `using`). Although a
`StringReader` won't leak file handles, the pattern is still surprising. Use
the simpler, no-allocation alternative:
```scala
raw.linesIterator.foreach { ... }
```
(`linesIterator` is available since Scala 2.13; if the project still targets
2.12, `raw.split("\n", -1).iterator` is equivalent.)
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