From 4ae4f0e76a1fe84371809cc065ec15f0137e72ff Mon Sep 17 00:00:00 2001
From: Andy Zhang <andyzzlms@outlook.com>
Date: Fri, 8 Jan 2021 10:18:49 +0800
Subject: [PATCH] ReadWriteSafeCache concurrency read-write (#6149)

---
 CHANGES.md                                                    | 1 +
 .../oap/server/core/analysis/data/ReadWriteSafeCache.java     | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index 509b50177c..466d45e977 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -52,6 +52,7 @@ Release Notes.
 * Fix the priority setting doesn't work of the ALS analyzers.
 * Fix bug that `endpoint-name-grouping.yml` is not customizable in Dockerized case.
 * Fix bug that istio version metric type on UI template mismatches the otel rule.
+* Improve ReadWriteSafeCache concurrency read-write performance
 
 #### UI
 * Fix un-removed tags in trace query.
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/data/ReadWriteSafeCache.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/data/ReadWriteSafeCache.java
index e73bbfbd80..7fa8ff25db 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/data/ReadWriteSafeCache.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/data/ReadWriteSafeCache.java
@@ -85,10 +85,10 @@ public class ReadWriteSafeCache<T> {
             BufferedData<T> tempPointer = writeBufferPointer;
             writeBufferPointer = readBufferPointer;
             readBufferPointer = tempPointer;
-
-            return readBufferPointer.read();
         } finally {
             lock.unlock();
         }
+        // Call read method outside of write lock for concurrency read-write.
+        return readBufferPointer.read();
     }
 }
-- 
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