Fix JVM <clinit> deadlock by removing static final accessor fields

Remove all 49 'private static final XxxAccessor' fields from consuming
classes and replace with inline calls to the getter. These fields
triggered initializeAllAccessors() during <clinit>, creating circular
class initialization dependencies that permanently deadlocked the JVM
when multiple threads concurrently loaded Cosmos classes.

The accessor is already cached inside ImplementationBridgeHelpers via
AtomicReference — the static fields were a redundant cache. Inline
calls add one volatile read (~1ns) per access, negligible vs the
actual Cosmos operations.

Also includes:
- Missing static { initialize(); } blocks for 3 classes
- CosmosItemSerializer <clinit> ordering fix
- Renamed misnamed accessor in CosmosDiagnosticsThresholdsHelper
- Forked-JVM deadlock regression test (invocationCount=5, 12 threads)
- Behavioral enforcement test for static { initialize(); } blocks

Fixes: #48622
Fixes: #48585

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jeet1995

sdk/cosmos/azure-cosmos-tests/src/test/java/com/azure/cosmos/implementation/ImplementationBridgeHelpersTest.java

@@ -7,7 +7,8 @@
 #### Breaking Changes
 
 #### Bugs Fixed
-Fixing an NPE caused due to boxed Boolean conversion. - See [PR 48656](https://github.com/Azure/azure-sdk-for-java/pull/48656/)
+* Fixing an NPE caused due to boxed Boolean conversion. - See [PR 48656](https://github.com/Azure/azure-sdk-for-java/pull/48656/)
+* Fixed JVM `<clinit>` deadlock when multiple threads concurrently trigger Cosmos SDK class loading for the first time. - See [PR 48667](https://github.com/Azure/azure-sdk-for-java/pull/48667)
 
 #### Other Changes
 

sdk/cosmos/azure-cosmos/CHANGELOG.md

@@ -82,19 +82,6 @@ public final class CosmosAsyncClient implements Closeable {
     private static final Logger logger = LoggerFactory.getLogger(CosmosAsyncClient.class);
 
     private static final CosmosClientTelemetryConfig DEFAULT_TELEMETRY_CONFIG = new CosmosClientTelemetryConfig();
-    private static final ImplementationBridgeHelpers.CosmosQueryRequestOptionsHelper.CosmosQueryRequestOptionsAccessor queryOptionsAccessor =
-        ImplementationBridgeHelpers.CosmosQueryRequestOptionsHelper.getCosmosQueryRequestOptionsAccessor();
-    private static final ImplementationBridgeHelpers.FeedResponseHelper.FeedResponseAccessor feedResponseAccessor =
-        ImplementationBridgeHelpers.FeedResponseHelper.getFeedResponseAccessor();
-    private static final ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.CosmosClientTelemetryConfigAccessor
-        telemetryConfigAccessor = ImplementationBridgeHelpers
-        .CosmosClientTelemetryConfigHelper
-        .getCosmosClientTelemetryConfigAccessor();
-
-    private static final ImplementationBridgeHelpers.ReadConsistencyStrategyHelper.ReadConsistencyStrategyAccessor
-        readConsistencyStrategyAccessor = ImplementationBridgeHelpers
-            .ReadConsistencyStrategyHelper
-            .getReadConsistencyStrategyAccessor();
 
     private final static Function<CosmosAsyncContainer, CosmosAsyncContainer> DEFAULT_CONTAINER_FACTORY =
         (originalContainer) -> originalContainer;
@@ -148,7 +135,7 @@ public final class CosmosAsyncClient implements Closeable {
         this.clientTelemetryConfig = effectiveTelemetryConfig;
         boolean contentResponseOnWriteEnabled = builder.isContentResponseOnWriteEnabled();
         ApiType apiType = builder.apiType();
-        String clientCorrelationId = telemetryConfigAccessor
+        String clientCorrelationId = ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor()
             .getClientCorrelationId(effectiveTelemetryConfig);
 
         List<Permission> permissionList = new ArrayList<>();
@@ -207,15 +194,14 @@ public final class CosmosAsyncClient implements Closeable {
             TagName.ClientCorrelationId.toString(),
             ClientTelemetryMetrics.escape(effectiveClientCorrelationId));
 
-        this.clientMetricRegistrySnapshot = telemetryConfigAccessor
+        this.clientMetricRegistrySnapshot = ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor()
             .getClientMetricRegistry(effectiveTelemetryConfig);
 
-        CosmosMeterOptions cpuMeterOptions = telemetryConfigAccessor
+        CosmosMeterOptions cpuMeterOptions = ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor()
             .getMeterOptions(effectiveTelemetryConfig, CosmosMetricName.SYSTEM_CPU);
-        CosmosMeterOptions memoryMeterOptions = telemetryConfigAccessor
+        CosmosMeterOptions memoryMeterOptions = ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor()
             .getMeterOptions(effectiveTelemetryConfig, CosmosMetricName.SYSTEM_MEMORY_FREE);
 
-
         if (clientMetricRegistrySnapshot != null) {
             ClientTelemetryMetrics.add(clientMetricRegistrySnapshot, cpuMeterOptions, memoryMeterOptions);
         }
@@ -224,15 +210,15 @@ public final class CosmosAsyncClient implements Closeable {
         );
 
         if (this.clientMetricRegistrySnapshot != null) {
-            telemetryConfigAccessor.setClientCorrelationTag(
+            ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor().setClientCorrelationTag(
                 effectiveTelemetryConfig,
                 this.clientCorrelationTag );
-            telemetryConfigAccessor.setAccountName(
+            ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor().setAccountName(
                 effectiveTelemetryConfig,
                 this.accountTagValue
             );
 
-            telemetryConfigAccessor.addDiagnosticsHandler(
+            ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor().addDiagnosticsHandler(
                 effectiveTelemetryConfig,
                 new ClientMetricsDiagnosticsHandler(this)
             );
@@ -475,7 +461,7 @@ CosmosPagedFlux<CosmosDatabaseProperties> readAllDatabases(CosmosQueryRequestOpt
                 null,
                 ResourceType.Database,
                 OperationType.ReadFeed,
-                queryOptionsAccessor.getQueryNameOrDefault(nonNullOptions, spanName),
+                ImplementationBridgeHelpers.CosmosQueryRequestOptionsHelper.getCosmosQueryRequestOptionsAccessor().getQueryNameOrDefault(nonNullOptions, spanName),
                 nonNullOptions,
                 pagedFluxOptions
             );
@@ -484,7 +470,7 @@ CosmosPagedFlux<CosmosDatabaseProperties> readAllDatabases(CosmosQueryRequestOpt
 
             return getDocClientWrapper().readDatabases(state)
                 .map(response ->
-                    feedResponseAccessor.createFeedResponse(
+                    ImplementationBridgeHelpers.FeedResponseHelper.getFeedResponseAccessor().createFeedResponse(
                         ModelBridgeInternal.getCosmosDatabasePropertiesFromV2Results(response.getResults()),
                         response.getResponseHeaders(),
                         response.getCosmosDiagnostics()));
@@ -504,7 +490,6 @@ public CosmosPagedFlux<CosmosDatabaseProperties> readAllDatabases() {
         return readAllDatabases(new CosmosQueryRequestOptions());
     }
 
-
     /**
      * Query for databases.
      * <br/>
@@ -662,22 +647,21 @@ private CosmosPagedFlux<CosmosDatabaseProperties> queryDatabasesInternal(
                 null,
                 ResourceType.Database,
                 OperationType.Query,
-                queryOptionsAccessor.getQueryNameOrDefault(nonNullOptions, spanName),
+                ImplementationBridgeHelpers.CosmosQueryRequestOptionsHelper.getCosmosQueryRequestOptionsAccessor().getQueryNameOrDefault(nonNullOptions, spanName),
                 nonNullOptions,
                 pagedFluxOptions
             );
 
             pagedFluxOptions.setFeedOperationState(state);
 
             return getDocClientWrapper().queryDatabases(querySpec, state)
-                .map(response -> feedResponseAccessor.createFeedResponse(
+                .map(response -> ImplementationBridgeHelpers.FeedResponseHelper.getFeedResponseAccessor().createFeedResponse(
                     ModelBridgeInternal.getCosmosDatabasePropertiesFromV2Results(response.getResults()),
                     response.getResponseHeaders(),
                     response.getCosmosDiagnostics()));
         });
     }
 
-
     private Mono<CosmosDatabaseResponse> createDatabaseIfNotExistsInternal(CosmosAsyncDatabase database,
                                                                            ThroughputProperties throughputProperties, Context context) {
         String spanName = "createDatabaseIfNotExists." + database.getId();
@@ -765,7 +749,7 @@ ReadConsistencyStrategy getEffectiveReadConsistencyStrategy(
         OperationType operationType,
         ReadConsistencyStrategy desiredReadConsistencyStrategyOfOperation) {
 
-        return readConsistencyStrategyAccessor.getEffectiveReadConsistencyStrategy(
+        return ImplementationBridgeHelpers.ReadConsistencyStrategyHelper.getReadConsistencyStrategyAccessor().getEffectiveReadConsistencyStrategy(
             resourceType,
             operationType,
             desiredReadConsistencyStrategyOfOperation,
@@ -780,13 +764,12 @@ CosmosDiagnosticsThresholds getEffectiveDiagnosticsThresholds(
             return operationLevelThresholds;
         }
 
-
         if (this.clientTelemetryConfig == null) {
             return new CosmosDiagnosticsThresholds();
         }
 
         CosmosDiagnosticsThresholds clientLevelThresholds =
-            telemetryConfigAccessor.getDiagnosticsThresholds(this.clientTelemetryConfig);
+            ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor().getDiagnosticsThresholds(this.clientTelemetryConfig);
 
         return clientLevelThresholds != null ? clientLevelThresholds : new CosmosDiagnosticsThresholds();
     }
@@ -805,15 +788,15 @@ boolean isTransportLevelTracingEnabled() {
             this.clientTelemetryConfig
             : DEFAULT_TELEMETRY_CONFIG;
 
-        if (telemetryConfigAccessor.isLegacyTracingEnabled(effectiveConfig)) {
+        if (ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor().isLegacyTracingEnabled(effectiveConfig)) {
             return false;
         }
 
         if (this.getConnectionPolicy().getConnectionMode() != ConnectionMode.DIRECT) {
             return false;
         }
 
-        return telemetryConfigAccessor.isTransportLevelTracingEnabled(effectiveConfig);
+        return ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor().isTransportLevelTracingEnabled(effectiveConfig);
     }
 
     void recordOpenConnectionsAndInitCachesCompleted(List<CosmosContainerIdentity> cosmosContainerIdentities) {
@@ -859,13 +842,13 @@ public String getAccountTagValue(CosmosAsyncClient client) {
 
                 @Override
                 public EnumSet<TagName> getMetricTagNames(CosmosAsyncClient client) {
-                    return  telemetryConfigAccessor
+                    return  ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor()
                         .getMetricTagNames(client.clientTelemetryConfig);
                 }
 
                 @Override
                 public EnumSet<MetricCategory> getMetricCategories(CosmosAsyncClient client) {
-                    return  telemetryConfigAccessor
+                    return  ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor()
                         .getMetricCategories(client.clientTelemetryConfig);
                 }
 
@@ -896,7 +879,7 @@ public String getUserAgent(CosmosAsyncClient client) {
 
                 @Override
                 public CosmosMeterOptions getMeterOptions(CosmosAsyncClient client, CosmosMetricName name) {
-                    return  telemetryConfigAccessor
+                    return  ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor()
                         .getMeterOptions(client.clientTelemetryConfig, name);
                 }