ConcurrentModificationException when late meter filters are added

Fixes micrometer-metrics#5489 Signed-off-by: Martin Bartoš <mabartos@redhat.com>
mabartos · Sep 24, 2024 · 84e5423 · 84e5423
1 parent 4b6b761
commit 84e5423
Showing 1 changed file with 7 additions and 2 deletions.
diff --git a/micrometer-core/src/main/java/io/micrometer/core/instrument/MeterRegistry.java b/micrometer-core/src/main/java/io/micrometer/core/instrument/MeterRegistry.java
@@ -108,7 +108,10 @@ public abstract class MeterRegistry {
      */
     private final Map<Id, Meter> preFilterIdToMeterMap = new HashMap<>();
 
-    // not thread safe; only needed when MeterFilter configured after Meters registered
+    /**
+     * Only needed when MeterFilter configured after Meters registered.
+     * Write/remove guarded by meterMapLock, otherwise unguarded
+     */
     private final Set<Id> stalePreFilterIds = new HashSet<>();
 
     /**
@@ -829,7 +832,9 @@ public Config commonTags(String... tags) {
         public synchronized Config meterFilter(MeterFilter filter) {
             if (!meterMap.isEmpty()) {
                 logWarningAboutLateFilter();
-                stalePreFilterIds.addAll(preFilterIdToMeterMap.keySet());
+                synchronized (meterMapLock) {
+                    stalePreFilterIds.addAll(preFilterIdToMeterMap.keySet());
+                }
             }
             MeterFilter[] newFilters = new MeterFilter[filters.length + 1];
             System.arraycopy(filters, 0, newFilters, 0, filters.length);