From 073048abf2e67161457c33a7403149db025bc14d Mon Sep 17 00:00:00 2001
From: John Verwolf <JVerwolf@users.noreply.github.com>
Date: Mon, 8 Apr 2024 09:28:34 -0700
Subject: [PATCH] Track ongoing search tasks (#107129)

---
 docs/changelog/107129.yaml                     |  5 +++++
 .../elasticsearch/threadpool/ThreadPool.java   | 18 ++++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 docs/changelog/107129.yaml

diff --git a/docs/changelog/107129.yaml b/docs/changelog/107129.yaml
new file mode 100644
index 0000000000000..6c9b9094962c1
--- /dev/null
+++ b/docs/changelog/107129.yaml
@@ -0,0 +1,5 @@
+pr: 107129
+summary: Track ongoing search tasks
+area: Search
+type: enhancement
+issues: []
diff --git a/server/src/main/java/org/elasticsearch/threadpool/ThreadPool.java b/server/src/main/java/org/elasticsearch/threadpool/ThreadPool.java
index cf554fe81d4a3..507eff05780b8 100644
--- a/server/src/main/java/org/elasticsearch/threadpool/ThreadPool.java
+++ b/server/src/main/java/org/elasticsearch/threadpool/ThreadPool.java
@@ -151,6 +151,8 @@ public static ThreadPoolType fromType(String type) {
         entry(Names.SYSTEM_CRITICAL_WRITE, ThreadPoolType.FIXED)
     );
 
+    public static final double searchAutoscalingEWMA = 0.1;
+
     private final Map<String, ExecutorHolder> executors;
 
     private final ThreadPoolInfo threadPoolInfo;
@@ -222,7 +224,13 @@ public ThreadPool(final Settings settings, MeterRegistry meterRegistry, final Ex
         builders.put(Names.ANALYZE, new FixedExecutorBuilder(settings, Names.ANALYZE, 1, 16, TaskTrackingConfig.DO_NOT_TRACK));
         builders.put(
             Names.SEARCH,
-            new FixedExecutorBuilder(settings, Names.SEARCH, searchOrGetThreadPoolSize, 1000, TaskTrackingConfig.DEFAULT)
+            new FixedExecutorBuilder(
+                settings,
+                Names.SEARCH,
+                searchOrGetThreadPoolSize,
+                1000,
+                new TaskTrackingConfig(true, searchAutoscalingEWMA)
+            )
         );
         builders.put(
             Names.SEARCH_WORKER,
@@ -230,7 +238,13 @@ public ThreadPool(final Settings settings, MeterRegistry meterRegistry, final Ex
         );
         builders.put(
             Names.SEARCH_COORDINATION,
-            new FixedExecutorBuilder(settings, Names.SEARCH_COORDINATION, halfProc, 1000, TaskTrackingConfig.DEFAULT)
+            new FixedExecutorBuilder(
+                settings,
+                Names.SEARCH_COORDINATION,
+                halfProc,
+                1000,
+                new TaskTrackingConfig(true, searchAutoscalingEWMA)
+            )
         );
         builders.put(
             Names.AUTO_COMPLETE,