From e8be8239709a06e58fb603f9c53a7af7c67b1d71 Mon Sep 17 00:00:00 2001
From: Sairam Cherupally <sairamc@uber.com>
Date: Sat, 15 Feb 2020 07:22:33 +0530
Subject: [PATCH] remove global lock for subscope computation

---
 .../java/com/uber/m3/tally/ScopeImpl.java     | 31 ++++++-------------
 1 file changed, 10 insertions(+), 21 deletions(-)

diff --git a/core/src/main/java/com/uber/m3/tally/ScopeImpl.java b/core/src/main/java/com/uber/m3/tally/ScopeImpl.java
index 86fb667..c943a7b 100644
--- a/core/src/main/java/com/uber/m3/tally/ScopeImpl.java
+++ b/core/src/main/java/com/uber/m3/tally/ScopeImpl.java
@@ -331,26 +331,16 @@ private Scope subScopeHelper(String prefix, Map<String, String> tags) {
 
         String key = keyForPrefixedStringMap(prefix, mergedTags);
 
-        Scope subscope;
-
-        synchronized (registry.allocationLock) {
-            if (!registry.subscopes.containsKey(key)) {
-                registry.subscopes.put(
-                    key,
-                    new ScopeBuilder(scheduler, registry)
-                        .reporter(reporter)
-                        .prefix(prefix)
-                        .separator(separator)
-                        .tags(mergedTags)
-                        .defaultBuckets(defaultBuckets)
-                        .build()
-                );
-            }
-
-            subscope = registry.subscopes.get(key);
-        }
-
-        return subscope;
+        return registry.subscopes.computeIfAbsent(
+            key,
+            (k) -> new ScopeBuilder(scheduler, registry)
+                .reporter(reporter)
+                .prefix(prefix)
+                .separator(separator)
+                .tags(mergedTags)
+                .defaultBuckets(defaultBuckets)
+                .build()
+        );
     }
 
     // One iteration of reporting this scope and all its subscopes
@@ -391,7 +381,6 @@ private void reportUncaughtException(Exception uncaughtException) {
     }
 
     static class Registry {
-        final Object allocationLock = new Object();
         Map<String, ScopeImpl> subscopes = new ConcurrentHashMap<>();
     }
 }