Attempt to fix reference counting issues in ES client instrumentation (#3256)

Author: JonasKunz

CHANGELOG.asciidoc

@@ -40,6 +40,7 @@ Use subheadings with the "=====" level for adding notes for unreleased changes:
 [float]
 ===== Bug fixes
 * Fixed SQS NoClassDefFoundError in AWS SDK instrumentation - {pull}3254[#3254]
+* Fixed reference counting issues in elasticsearch instrumentation - {pull}3256[#3256]
 
 [[release-notes-1.x]]
 === Java Agent version 1.x

apm-agent-plugins/apm-es-restclient-plugin/apm-es-restclient-plugin-common/src/main/java/co/elastic/apm/agent/esrestclient/ResponseListenerWrapper.java

@@ -53,15 +53,15 @@ ResponseListenerWrapper withClientSpan(ResponseListener delegate, Span<?> span)
  // Order is important due to visibility - write to span last on this (initiating) thread
  this.delegate = delegate;
  this.isClientSpan = true;
- this.context = span;
+ setContext(span);
  return this;
  }
 
  ResponseListenerWrapper withContextPropagation(ResponseListener delegate, AbstractSpan<?> context) {
  // Order is important due to visibility - write to span last on this (initiating) thread
  this.delegate = delegate;
  this.isClientSpan = false;
- this.context = context;
+ setContext(context);
  return this;
  }
 
@@ -149,10 +149,20 @@ private void finishClientSpan(@Nullable Response response, @Nullable Throwable t
  }
  }
 
+ private void setContext(@Nullable AbstractSpan<?> newContext) {
+ if (newContext != null) {
+ newContext.incrementReferences();
+ }
+ if (context != null) {
+ context.decrementReferences();
+ }
+ context = newContext;
+ }
+
  @Override
  public void resetState() {
  delegate = null;
- context = null;
+ setContext(null);
  isClientSpan = false;
  }
 }