Fix JVM <clinit> deadlock by removing static final accessor fields by jeet1995 · Pull Request #48689 · Azure/azure-sdk-for-java

jeet1995 · 2026-04-03T23:20:40Z

Summary

Fixes a JVM-level <clinit> deadlock that occurs when multiple threads concurrently trigger Cosmos SDK class loading for the first time. This is a permanent, unrecoverable deadlock that hangs all affected threads indefinitely.

Fixes: #48622, #48585

Root Cause

Consuming classes cache accessors in private static final fields:

private static final FeedResponseAccessor feedResponseAccessor =
    ImplementationBridgeHelpers.FeedResponseHelper.getFeedResponseAccessor();

During <clinit>, the getter finds the accessor null and calls initializeAllAccessors(), which eagerly loads 40+ classes. When two threads enter <clinit> of different classes simultaneously, the JVM's per-class initialization locks create a circular wait — permanent deadlock.

Fix

Remove all 49 private static final XxxAccessor fields and replace with inline calls to the getter:

// Before — triggers initializeAllAccessors() during <clinit>
private static final FeedResponseAccessor feedResponseAccessor =
    ImplementationBridgeHelpers.FeedResponseHelper.getFeedResponseAccessor();
feedResponseAccessor.createFeedResponse(...)

// After — no <clinit> involvement, accessor resolved lazily on first use
ImplementationBridgeHelpers.FeedResponseHelper.getFeedResponseAccessor().createFeedResponse(...)

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 actual Cosmos operations.

Why this approach

Approach	Problem
`Class.forName()` in getters	Can't force accessor registration during recursive `<clinit>` (JLS §12.4.2 no-op). Also reverts Fabian's intentional removal in PR #28912
`initializeAllAccessors()` from `<clinit>`	The root cause — loads 40+ classes, creates circular dependency
Bridge methods	Can't add methods to `*BridgeInternal` classes
Make `initialize()` public	Not allowed
`CosmosClientBuilder.static{}`	Doesn't cover customer code touching model classes before building a client
Remove static final fields	Zero classloader risk, zero `<clinit>` involvement, zero recursive edge cases

Additional fixes

Added missing static { initialize(); } to CosmosRequestContext, CosmosOperationDetails, CosmosDiagnosticsContext
Fixed <clinit> ordering in CosmosItemSerializer — moved static { initialize(); } before DEFAULT_SERIALIZER
Renamed getCosmosAsyncClientAccessor() → getCosmosDiagnosticsThresholdsAccessor() in CosmosDiagnosticsThresholdsHelper

Files Changed

49 static final accessor fields removed across 27 consuming classes. No changes to ImplementationBridgeHelpers.java itself.

Tests

concurrentAccessorInitializationShouldNotDeadlock (invocationCount=5) — forks fresh child JVMs, 12 threads via CyclicBarrier concurrently triggering <clinit>
allAccessorClassesMustHaveStaticInitializerBlock — behavioral enforcement via forked JVM, verifies every accessor is non-null after <clinit>
accessorInitialization — existing test, validates explicit initializeAllAccessors() bootstrap path

jeet1995 · 2026-04-03T23:23:45Z

Closing — bridge classes don't allow adding new methods. Proceeding with #48667 (Class.forName with explicit classloader).

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: Azure#48622 Fixes: Azure#48585 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jeet1995 · 2026-04-04T00:06:31Z

/azp run java - cosmos - ci

jeet1995 · 2026-04-04T00:06:32Z

/azp run java - cosmos - tests

jeet1995 · 2026-04-04T00:06:33Z

/azp run java - cosmos - kafka

jeet1995 · 2026-04-04T00:06:34Z

/azp run java - cosmos - spark

jeet1995 · 2026-04-04T00:06:35Z

/azp run java - spring - ci

azure-pipelines · 2026-04-04T00:06:44Z

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azure-pipelines · 2026-04-04T00:06:47Z

Azure Pipelines successfully started running 1 pipeline(s).

azure-pipelines · 2026-04-04T00:06:48Z

Azure Pipelines successfully started running 1 pipeline(s).

azure-pipelines · 2026-04-04T00:06:48Z

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azure-pipelines · 2026-04-04T00:06:57Z

Azure Pipelines successfully started running 1 pipeline(s).

jeet1995 · 2026-04-05T00:31:07Z

/azp run java - cosmos - ci

azure-pipelines · 2026-04-05T00:31:34Z

Azure Pipelines successfully started running 1 pipeline(s).

Copilot

Pull request overview

This PR addresses a JVM <clinit> deadlock in the Cosmos Java SDK by removing many static final ...Accessor caches in consuming classes and switching call sites to resolve accessors lazily via ImplementationBridgeHelpers.*Helper.get*Accessor() on demand, reducing class-initialization-time cross-dependencies.

Changes:

Replaced numerous private static final XxxAccessor ... = getXxxAccessor() fields with inline (lazy) getter calls at usage sites.
Added/adjusted static { initialize(); } blocks and <clinit> ordering to ensure accessors are registered safely during class initialization where required.
Added forked-JVM regression/enforcement tests around concurrent <clinit> behavior and accessor registration.

Reviewed changes

Copilot reviewed 54 out of 54 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
sdk/spring/azure-spring-data-cosmos/README.md	Trailing whitespace/newline adjustment.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/util/CosmosPagedFluxStaticListImpl.java	Removed static accessor cache; inline FeedResponse accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/util/CosmosPagedFluxDefaultImpl.java	Removed static accessor cache; inline diagnostics context accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/models/FeedResponse.java	Removed static diagnostics accessor cache; inline accessor calls.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/models/CosmosOperationDetails.java	Added `static { initialize(); }` registration block.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/models/CosmosItemRequestOptions.java	Removed static thresholds accessor cache; inline thresholds accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/StaleResourceRetryPolicy.java	Removed static exception accessor cache.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/SessionTokenMismatchRetryPolicy.java	Removed static accessor cache; inline session retry options accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/RxDocumentClientImpl.java	Removed multiple static accessor caches; inline accessor usage across implementation.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/QueryPlanRetriever.java	Removed static accessor caches; inline accessors for options/exception handling.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/PipelinedQueryExecutionContext.java	Removed static accessor cache; inline accessor usage when cloning options.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/PipelinedDocumentQueryExecutionContext.java	Removed static accessor caches; inline options and serializer accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/ParallelDocumentQueryExecutionContext.java	Removed static accessor caches; inline options/diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/OrderByUtils.java	Removed static diagnostics accessor cache; inline diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/OrderByDocumentQueryExecutionContext.java	Removed static accessor caches; inline feed/diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/OrderByDocumentProducer.java	Removed static feed accessor cache; inline feed accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/NonStreamingOrderByUtils.java	Removed static diagnostics accessor cache; inline diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/NonStreamingOrderByDocumentQueryExecutionContext.java	Removed static accessor caches; inline feed/diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/HybridSearchDocumentQueryExecutionContext.java	Removed static accessor caches; inline feed/diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/GroupByDocumentQueryExecutionContext.java	Removed static diagnostics accessor cache; inline diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/Fetcher.java	Removed static diagnostics accessor cache; inline diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/DocumentQueryExecutionContextFactory.java	Inline options accessor usage in creation flow.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/DocumentQueryExecutionContextBase.java	Removed static accessor caches; inline accessor usage for request creation and cloning.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/DocumentProducer.java	Removed static accessor cache; inline accessor usage when cloning options.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/DefaultDocumentQueryExecutionContext.java	Removed static accessor cache; inline accessor usage for partition key definition/properties.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/DCountDocumentQueryExecutionContext.java	Removed static diagnostics accessor cache; inline diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/ChangeFeedFetcher.java	Removed static feed accessor cache; inline feed accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/query/AggregateDocumentQueryExecutionContext.java	Removed static accessor caches; inline feed/diagnostics accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/JsonSerializable.java	Removed static serializer accessor cache; inline serializer accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/ImplementationBridgeHelpers.java	Renamed thresholds accessor getter (`getCosmosAsyncClientAccessor` → `getCosmosDiagnosticsThresholdsAccessor`).
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/http/HttpClientConfig.java	Removed static HTTP2 config accessor cache; inline accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/Document.java	Removed static serializer accessor cache; inline serializer accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/directconnectivity/GoneAndRetryWithRetryPolicy.java	Removed static exception accessor cache; inline exception accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/DiagnosticsProvider.java	Removed multiple static accessor caches; inline accessors throughout tracing/metrics paths.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/CosmosQueryRequestOptionsImpl.java	Updated thresholds accessor getter name usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/CosmosQueryRequestOptionsBase.java	Updated thresholds accessor getter name usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/ConnectionPolicy.java	Removed static HTTP2 config accessor cache; inline accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/clienttelemetry/ClientTelemetryMetrics.java	Removed static accessor caches; inline accessors for telemetry metrics recording.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/clienttelemetry/ClientMetricsDiagnosticsHandler.java	Removed static telemetry config accessor cache.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/ChangeFeedQueryImpl.java	Removed static accessor caches; inline accessors for change feed request/response.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/caches/RxCollectionCache.java	Removed static exception accessor cache; inline exception accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/batch/TransactionalBulkExecutor.java	Removed static batch request options accessor cache; inline accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/batch/BulkExecutor.java	Removed static accessor caches; inline accessors for batch response and diagnostics provider.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosRequestContext.java	Added `static { initialize(); }` registration block.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosItemSerializer.java	Reordered `<clinit>` to register accessor before static fields.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosDiagnosticsContext.java	Added `static { initialize(); }` registration block.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosContainerProactiveInitConfig.java	Removed static container identity accessor cache; inline accessor usage.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosAsyncUser.java	Removed static accessor caches; inline accessors for query naming/feed response creation.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosAsyncScripts.java	Removed static accessor caches; inline accessors for query naming/feed response creation.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosAsyncDatabase.java	Removed static accessor caches; inline accessors for query naming/feed response creation.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosAsyncContainer.java	Removed many static accessor caches; inline accessors across request/response, policies, and telemetry.
sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosAsyncClient.java	Removed static accessor caches; inline telemetry/options/feed response accessors.
sdk/cosmos/azure-cosmos/CHANGELOG.md	Added changelog bullet for `<clinit>` deadlock fix.
sdk/cosmos/azure-cosmos-tests/src/test/java/com/azure/cosmos/implementation/ImplementationBridgeHelpersTest.java	Added forked-JVM deadlock regression test and accessor registration enforcement test.

Copilot · 2026-04-05T00:39:18Z

...rc/main/java/com/azure/cosmos/implementation/query/DocumentQueryExecutionContextFactory.java

@@ -59,7 +59,6 @@ public class DocumentQueryExecutionContextFactory {

    private final static int PageSizeFactorForTop = 5;
    private static final Logger logger = LoggerFactory.getLogger(DocumentQueryExecutionContextFactory.class);


DocumentQueryExecutionContextFactory still has a static final CosmosQueryRequestOptionsAccessor (qryOptAccessor) that is initialized during this class’ <clinit> via getCosmosQueryRequestOptionsAccessor(). This reintroduces the class-initialization-time accessor resolution pattern this PR is trying to eliminate and can put initializeAllAccessors() back on a <clinit> path. Please remove this static accessor field and resolve the accessor lazily at the point of use (e.g., inline getter call or a method-local variable).

Copilot · 2026-04-05T00:39:18Z

...zure-cosmos/src/main/java/com/azure/cosmos/implementation/CosmosQueryRequestOptionsBase.java

 public abstract class CosmosQueryRequestOptionsBase<T extends CosmosQueryRequestOptionsBase<?>> implements OverridableRequestOptions {
    private final static ImplementationBridgeHelpers.CosmosDiagnosticsThresholdsHelper.CosmosDiagnosticsThresholdsAccessor thresholdsAccessor =
-        ImplementationBridgeHelpers.CosmosDiagnosticsThresholdsHelper.getCosmosAsyncClientAccessor();
+        ImplementationBridgeHelpers.CosmosDiagnosticsThresholdsHelper.getCosmosDiagnosticsThresholdsAccessor();



CosmosQueryRequestOptionsBase still initializes thresholdsAccessor as a static final field by calling getCosmosDiagnosticsThresholdsAccessor() during class initialization. This is the same pattern that can trigger accessor initialization during <clinit> and can reintroduce the deadlock this PR is addressing. Please remove this static field and resolve the accessor lazily (inline call or method-local caching) where it’s needed.

Copilot · 2026-04-05T00:39:18Z

...zure-cosmos/src/main/java/com/azure/cosmos/implementation/CosmosQueryRequestOptionsImpl.java

 public final class CosmosQueryRequestOptionsImpl extends CosmosQueryRequestOptionsBase<CosmosQueryRequestOptionsImpl> {
    private final static ImplementationBridgeHelpers.CosmosDiagnosticsThresholdsHelper.CosmosDiagnosticsThresholdsAccessor thresholdsAccessor =
-        ImplementationBridgeHelpers.CosmosDiagnosticsThresholdsHelper.getCosmosAsyncClientAccessor();
+        ImplementationBridgeHelpers.CosmosDiagnosticsThresholdsHelper.getCosmosDiagnosticsThresholdsAccessor();
    private String partitionKeyRangeId;


CosmosQueryRequestOptionsImpl still initializes thresholdsAccessor as a static final field by calling getCosmosDiagnosticsThresholdsAccessor() during <clinit>. This keeps accessor resolution on a class-initialization path and can reintroduce the deadlock scenario. Please remove this static field and resolve the accessor lazily at the call sites (optionally cache in a method-local variable).

Copilot · 2026-04-05T00:39:18Z

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

+     * Enforces that every class targeted by {@code ensureClassInitialized()} in
+     * {@link ImplementationBridgeHelpers} registers its accessor during {@code <clinit>}
+     * (i.e., has a {@code static { initialize(); }} block).
+     * <p>
+     * Verification is behavioral, not source-based: a forked child JVM iterates every


The JavaDoc for allAccessorClassesMustHaveStaticInitializerBlock refers to ensureClassInitialized() and claims the getter triggers Class.forName() → <clinit> and will fail if static { initialize(); } is missing. In the current ImplementationBridgeHelpers implementation, getters call initializeAllAccessors() (not a targeted Class.forName()), so this test can pass even when a class doesn’t register its accessor during <clinit> (because initializeAllAccessors() can set accessors directly). Please adjust the test (or the infrastructure) so it actually enforces the intended contract.

Copilot · 2026-04-05T00:39:19Z

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

+     * timeout detects the hang. Runs 5 invocations via TestNG ({@code invocationCount = 5}),
+     * each forking 3 child JVMs — totaling 15 fresh JVMs × 12 concurrent threads = 180
+     * {@code <clinit>} race attempts.
+     */
+    @Test(groups = { "unit" }, invocationCount = 5)
+    public void concurrentAccessorInitializationShouldNotDeadlock() throws Exception {


concurrentAccessorInitializationShouldNotDeadlock is marked as a unit test but forks multiple child JVMs (invocationCount=5 and an inner runs=3, i.e., 15 JVM forks per test execution). This is likely to add substantial runtime/overhead to the unit test suite and increase flakiness on constrained CI agents. Consider moving this to a heavier-weight test group (or reducing the fork count) while keeping the regression coverage.

Copilot · 2026-04-05T00:39:19Z

...re-cosmos/src/main/java/com/azure/cosmos/implementation/SessionTokenMismatchRetryPolicy.java

            this.maxRetryAttemptsInCurrentRegion =
-                new AtomicInteger(sessionRetryOptionsAccessor.getMaxInRegionRetryCount(sessionRetryOptions));
-            this.regionSwitchHint = sessionRetryOptionsAccessor.getRegionSwitchHint(sessionRetryOptions);
-            this.minInRegionRetryTime = sessionRetryOptionsAccessor.getMinInRegionRetryTime(sessionRetryOptions);
+                new AtomicInteger(ImplementationBridgeHelpers.CosmosSessionRetryOptionsHelper.getCosmosSessionRetryOptionsAccessor().getMaxInRegionRetryCount(sessionRetryOptions));
+            this.regionSwitchHint = ImplementationBridgeHelpers.CosmosSessionRetryOptionsHelper.getCosmosSessionRetryOptionsAccessor().getRegionSwitchHint(sessionRetryOptions);
+            this.minInRegionRetryTime = ImplementationBridgeHelpers.CosmosSessionRetryOptionsHelper.getCosmosSessionRetryOptionsAccessor().getMinInRegionRetryTime(sessionRetryOptions);


These inlined accessor calls create very long lines (likely exceeding the 120-character Checkstyle LineLength limit) and are harder to read. Consider storing the accessor in a method-local variable (safe w.r.t. <clinit> deadlock) and/or wrapping the call chain across lines to satisfy the repository’s Checkstyle line-length rule (e.g., eng/lintingconfigs/checkstyle/track2/checkstyle.xml).

Copilot · 2026-04-05T00:39:19Z

sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/RxDocumentClientImpl.java

    public CosmosDiagnostics createDiagnostics() {
       CosmosDiagnostics diagnostics =
-           diagnosticsAccessor.create(this, telemetryCfgAccessor.getSamplingRate(this.clientTelemetryConfig));
+           ImplementationBridgeHelpers.CosmosDiagnosticsHelper.getCosmosDiagnosticsAccessor().create(this, ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.getCosmosClientTelemetryConfigAccessor().getSamplingRate(this.clientTelemetryConfig));



This line is extremely long due to nested inline accessor calls and is likely to violate the 120-character Checkstyle LineLength rule. Please wrap this across multiple lines and/or use a method-local variable for the accessors to keep the code readable and compliant.

Copilot · 2026-04-05T00:39:19Z

sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/util/CosmosPagedFluxDefaultImpl.java

                                Duration.ofNanos(feedResponseConsumerLatencyInNanos.get()));

-                            tracerProvider.endSpan(ctxSnapshot, traceCtx, ctxAccessor.isEmptyCompletion(ctxSnapshot), isSampledOut);
+                            tracerProvider.endSpan(ctxSnapshot, traceCtx, ImplementationBridgeHelpers.CosmosDiagnosticsContextHelper.getCosmosDiagnosticsContextAccessor().isEmptyCompletion(ctxSnapshot), isSampledOut);



The endSpan call inlines another getCosmosDiagnosticsContextAccessor() invocation, making the line very long and repeating the accessor lookup. Please store the accessor (or isEmptyCompletion result) in a local variable and/or wrap the call across lines to avoid Checkstyle LineLength violations and reduce repeated volatile reads.

Copilot · 2026-04-05T00:39:20Z

sdk/cosmos/azure-cosmos/CHANGELOG.md

 #### 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)


The changelog entry for the <clinit> deadlock fix points to PR #48667, but this PR is described as an alternative approach. Please update the reference to point to the correct PR (this one) or otherwise clarify which change actually delivered the fix in this release line.

Pattern A (private final instance fields) — 18 files: CosmosAsyncClient, CosmosAsyncDatabase, CosmosAsyncScripts, CosmosAsyncUser, ConnectionPolicy, RxDocumentClientImpl, BulkExecutor, TransactionalBulkExecutor, HttpClientConfig, AggregateDocumentQueryExecutionContext, DefaultDocumentQueryExecutionContext, DocumentQueryExecutionContextBase, OrderByDocumentProducer, CosmosPagedFluxDefaultImpl, CosmosPagedFluxStaticListImpl Pattern B (private static lazy getter methods) — 11 files: CosmosAsyncContainer (11 methods), DiagnosticsProvider (3 methods), ClientTelemetryMetrics (1 method), DocumentProducer, DocumentQueryExecutionContextFactory, PipelinedDocumentQueryExecutionContext, PipelinedQueryExecutionContext, HybridSearchDocumentQueryExecutionContext, NonStreamingOrderByDocumentQueryExecutionContext, OrderByDocumentQueryExecutionContext, ParallelDocumentQueryExecutionContext 4 files originally listed as Pattern A were moved to Pattern B because their accessors are only used in static inner classes (ItemToPageTransformer, etc.). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jeet1995 · 2026-04-05T01:24:55Z

/azp run java - cosmos - ci

jeet1995 · 2026-04-05T01:24:56Z

/azp run java - cosmos - tests

jeet1995 · 2026-04-05T01:24:58Z

/azp run java - cosmos - kafka

jeet1995 · 2026-04-05T01:24:59Z

/azp run java - cosmos - spark

jeet1995 · 2026-04-05T01:25:01Z

/azp run java - spring - ci

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… stale docs - Removed remaining static final accessor fields in DocumentQueryExecutionContextFactory, CosmosQueryRequestOptionsBase, CosmosQueryRequestOptionsImpl - Extracted local variables for long inline accessor chains in SessionTokenMismatchRetryPolicy, RxDocumentClientImpl, CosmosPagedFluxDefaultImpl - Updated test Javadoc to reflect lazy accessor approach (not Class.forName) - Reduced child JVM runs from 3 to 1 (invocationCount=5 provides repetition) - Fixed CHANGELOG PR link to Azure#48689 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jeet1995 · 2026-04-05T01:56:08Z

/azp run java - cosmos - ci

jeet1995 · 2026-04-05T01:56:09Z

/azp run java - cosmos - tests

jeet1995 · 2026-04-05T01:56:11Z

/azp run java - cosmos - kafka

jeet1995 · 2026-04-05T01:56:12Z

/azp run java - cosmos - spark

jeet1995 · 2026-04-05T01:56:14Z

/azp run java - spring - ci

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jeet1995 · 2026-04-05T21:51:42Z

/azp run java - cosmos - ci

jeet1995 · 2026-04-05T21:51:43Z

/azp run java - cosmos - tests

jeet1995 · 2026-04-05T21:51:45Z

/azp run java - spring - ci

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github-actions bot added azure-spring All azure-spring related issues Cosmos labels Apr 3, 2026

jeet1995 closed this Apr 3, 2026

jeet1995 reopened this Apr 3, 2026

jeet1995 force-pushed the fix/clinit-deadlock-bridge-methods branch from e57066d to 66afd43 Compare April 4, 2026 00:05

jeet1995 changed the title ~~Fix JVM <clinit> deadlock using targeted bridge methods (alternative to #48667)~~ Fix JVM <clinit> deadlock by removing static final accessor fields (alternative to #48667) Apr 4, 2026

jeet1995 marked this pull request as ready for review April 5, 2026 00:30

jeet1995 requested review from a team, Netyyyy, kirankumarkolli, moarychan, rujche and saragluna as code owners April 5, 2026 00:30

Copilot AI review requested due to automatic review settings April 5, 2026 00:30

jeet1995 mentioned this pull request Apr 5, 2026

Fix JVM <clinit> deadlock in Cosmos SDK accessor initialization #48667

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jeet1995 changed the title ~~Fix JVM <clinit> deadlock by removing static final accessor fields (alternative to #48667)~~ Fix JVM <clinit> deadlock by removing static final accessor fields Apr 5, 2026

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		@@ -59,7 +59,6 @@ public class DocumentQueryExecutionContextFactory {

		private final static int PageSizeFactorForTop = 5;
		private static final Logger logger = LoggerFactory.getLogger(DocumentQueryExecutionContextFactory.class);

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Summary

Root Cause

Fix

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Tests

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jeet1995 commented Apr 3, 2026 •

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