AwsEventLoop always uses the system classloader

[justinas-dabravolskas]

Describe the bug

The AwsEventLoop thread uses the system class loader, which causes a ClassNotFoundException for custom javax.xml.stream.XMLInputFactory implementations that should be loaded by a child class loader. This issue becomes apparent when running a CRT client inside a Tomcat environment with the -Djavax.xml.stream.XMLInputFactory system property pointing to an implementation that is loaded by the custom child class loader instead of the system class loader.

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

AwsEventLoop should use the context class loader from which it was spawned instead of defaulting to a null value, which automatically defaults to the system class loader.

Current Behavior

Exception in thread "main" java.util.concurrent.ExecutionException: software.amazon.awssdk.core.exception.SdkClientException: Unable to execute HTTP request: Provider com.example.CustomInputFactory not found
at java.base/java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:396)
at java.base/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2073)
at org.example.App.aws(App.java:30)
at org.example.App.main(App.java:25)
Caused by: software.amazon.awssdk.core.exception.SdkClientException: Unable to execute HTTP request: Provider com.example.CustomInputFactory not found
at software.amazon.awssdk.core.exception.SdkClientException$BuilderImpl.build(SdkClientException.java:111)
at software.amazon.awssdk.core.exception.SdkClientException.create(SdkClientException.java:47)
at software.amazon.awssdk.core.internal.http.pipeline.stages.utils.RetryableStageHelper2.setLastException(RetryableStageHelper2.java:226)
at software.amazon.awssdk.core.internal.http.pipeline.stages.utils.RetryableStageHelper2.setLastException(RetryableStageHelper2.java:221)
at software.amazon.awssdk.core.internal.http.pipeline.stages.AsyncRetryableStage2$RetryingExecutor.maybeRetryExecute(AsyncRetryableStage2.java:151)
at software.amazon.awssdk.core.internal.http.pipeline.stages.AsyncRetryableStage2$RetryingExecutor.lambda$attemptExecute$1(AsyncRetryableStage2.java:113)
at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863)
at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2194)
at software.amazon.awssdk.utils.CompletableFutureUtils.lambda$forwardExceptionTo$0(CompletableFutureUtils.java:78)
at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863)
at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2194)
at software.amazon.awssdk.core.internal.http.pipeline.stages.MakeAsyncHttpRequestStage.lambda$execute$0(MakeAsyncHttpRequestStage.java:108)
at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863)
at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2194)
at software.amazon.awssdk.core.internal.http.pipeline.stages.MakeAsyncHttpRequestStage.completeResponseFuture(MakeAsyncHttpRequestStage.java:255)
at software.amazon.awssdk.core.internal.http.pipeline.stages.MakeAsyncHttpRequestStage.lambda$executeHttpRequest$3(MakeAsyncHttpRequestStage.java:167)
at java.base/java.util.concurrent.CompletableFuture.uniHandle(CompletableFuture.java:934)
at java.base/java.util.concurrent.CompletableFuture$UniHandle.tryFire(CompletableFuture.java:911)
at java.base/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:482)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
at java.base/java.lang.Thread.run(Thread.java:1583)
Caused by: javax.xml.stream.FactoryConfigurationError: Provider com.example.CustomInputFactory not found
at java.xml/javax.xml.stream.FactoryFinder.newInstance(FactoryFinder.java:184)
at java.xml/javax.xml.stream.FactoryFinder.newInstance(FactoryFinder.java:135)
at java.xml/javax.xml.stream.FactoryFinder.find(FactoryFinder.java:248)
at java.xml/javax.xml.stream.FactoryFinder.find(FactoryFinder.java:210)
at java.xml/javax.xml.stream.XMLInputFactory.newInstance(XMLInputFactory.java:166)
at software.amazon.awssdk.protocols.query.unmarshall.XmlDomParser.createXmlInputFactory(XmlDomParser.java:131)
at java.base/java.lang.ThreadLocal$SuppliedThreadLocal.initialValue(ThreadLocal.java:357)
at java.base/java.lang.ThreadLocal.setInitialValue(ThreadLocal.java:225)
at java.base/java.lang.ThreadLocal.get(ThreadLocal.java:194)
at java.base/java.lang.ThreadLocal.get(ThreadLocal.java:172)
at software.amazon.awssdk.protocols.query.unmarshall.XmlDomParser.parse(XmlDomParser.java:51)
at software.amazon.awssdk.protocols.xml.internal.unmarshall.XmlResponseParserUtils.parse(XmlResponseParserUtils.java:65)
at software.amazon.awssdk.protocols.xml.internal.unmarshall.AwsXmlPredicatedResponseHandler.parseResponse(AwsXmlPredicatedResponseHandler.java:116)
at software.amazon.awssdk.protocols.xml.internal.unmarshall.AwsXmlPredicatedResponseHandler.handleResponse(AwsXmlPredicatedResponseHandler.java:96)
at software.amazon.awssdk.protocols.xml.internal.unmarshall.AwsXmlPredicatedResponseHandler.handle(AwsXmlPredicatedResponseHandler.java:85)
at software.amazon.awssdk.protocols.xml.internal.unmarshall.AwsXmlPredicatedResponseHandler.handle(AwsXmlPredicatedResponseHandler.java:43)
at software.amazon.awssdk.core.internal.handler.BaseClientHandler.lambda$successTransformationResponseHandler$7(BaseClientHandler.java:279)
at software.amazon.awssdk.core.internal.http.async.AsyncResponseHandler.lambda$prepare$0(AsyncResponseHandler.java:92)
at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1150)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2179)
at software.amazon.awssdk.core.internal.http.async.AsyncResponseHandler$BaosSubscriber.onComplete(AsyncResponseHandler.java:135)
at software.amazon.awssdk.core.internal.metrics.BytesReadTrackingPublisher$BytesReadTracker.onComplete(BytesReadTrackingPublisher.java:74)
at software.amazon.awssdk.utils.async.SimplePublisher.doProcessQueue(SimplePublisher.java:275)
at software.amazon.awssdk.utils.async.SimplePublisher.processEventQueue(SimplePublisher.java:224)
at software.amazon.awssdk.utils.async.SimplePublisher.complete(SimplePublisher.java:157)
at software.amazon.awssdk.services.s3.internal.crt.S3CrtResponseHandlerAdapter.onSuccessfulResponseComplete(S3CrtResponseHandlerAdapter.java:159)
at software.amazon.awssdk.services.s3.internal.crt.S3CrtResponseHandlerAdapter.onFinished(S3CrtResponseHandlerAdapter.java:154)
at software.amazon.awssdk.crt.s3.S3MetaRequestResponseHandlerNativeAdapter.onFinished(S3MetaRequestResponseHandlerNativeAdapter.java:25)
Caused by: java.lang.ClassNotFoundException: com/example/CustomInputFactory
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:534)
at java.base/java.lang.Class.forName(Class.java:513)
at java.xml/javax.xml.stream.FactoryFinder.getProviderClass(FactoryFinder.java:108)
at java.xml/javax.xml.stream.FactoryFinder.newInstance(FactoryFinder.java:173)
... 28 more

Reproduction Steps

https://github.com/justinas-dabravolskas/aws-crt-classloader-reproduction/blob/main/app/src/main/java/org/example/App.java
This Gradle project simulates the ClassNotFoundException that occurs when running a CRT client within a Tomcat server, where the XmlInputFactory is loaded by the Tomcat class loader instead of the default system class loader.

To run the project, update the bucket and credentials in the build.gradle file.

Possible Solution

AwsEventLoop should take into account parent thread class loader.

Additional Information/Context

CRT clients should support a custom, system-wide XMLInputFactory, as it is common practice to enhance the performance and security of XML processing.

aws-crt-java version used

0.33.1

Java version used

21

Operating System and version

MacOS,Linux

[jmklix]

Working with the Java sdk team to investigate this issue.

[yk-littlepay]

I have similar issue, getting ClassNotFoundException (but the other class that was not found) when using DynamoDbEnhancedAsyncClient in gcr.io/distroless/java21-debian12:nonroot-arm64 while locally it works fine (MacOS arm64 15.2 Java Corretto 23.0.1-amzn)