[BUG] End the Elasticsearch exporter's wait on a read or write error

CHANGELOG.md

@@ -57,6 +57,9 @@ Increment the:
   request body on a 32-bit build
   [#4630](https://github.com/open-telemetry/opentelemetry-cpp/pull/4630)
 
+* [BUG] End the Elasticsearch exporter's wait on a read or write error
+  [#4331](https://github.com/open-telemetry/opentelemetry-cpp/pull/4331)
+
 ## [1.29.0] 2026-09-13
 
 * [RELEASE] Bump main branch to 1.29.0-dev (#4259)

exporters/elasticsearch/CMakeLists.txt

@@ -55,4 +55,8 @@ if(OTELCPP_BUILD_TESTING)
     TARGET es_log_record_exporter_test
     TEST_PREFIX exporter.
     TEST_LIST es_log_record_exporter_test)
+
+  # These cases exist to catch a wait that never returns. Without a per test
+  # bound a regression stalls the job instead of failing it.
+  set_tests_properties(${es_log_record_exporter_test} PROPERTIES TIMEOUT 30)
 endif() # OTELCPP_BUILD_TESTING

exporters/elasticsearch/src/es_log_record_exporter.cc

@@ -110,8 +110,8 @@ class ResponseHandler : public http_client::EventHandler
 
   /**
    * A method the user calls to block their thread until the request has either produced a
-   * response or failed. The longest duration is the timeout of the request, set by
-   * SetTimeoutMs(), which arrives here as a TimedOut session event.
+   * response or failed. It has no deadline of its own and relies on the HTTP client
+   * reporting one of the terminal session states.
    */
   bool waitForResponse()
   {
@@ -183,11 +183,15 @@ class ResponseHandler : public http_client::EventHandler
         OTEL_INTERNAL_LOG_ERROR("[ES Log Exporter] Network error");
         recordCompletion(CompletionState::Failure);
         break;
+      // Both of these end the session, so each has to release the waiter. Without that a
+      // synchronous export whose transfer fails this way blocks until the process ends.
       case http_client::SessionState::ReadError:
         OTEL_INTERNAL_LOG_DEBUG("[ES Log Exporter] Read error");
+        recordCompletion(CompletionState::Failure);
         break;
       case http_client::SessionState::WriteError:
         OTEL_INTERNAL_LOG_DEBUG("[ES Log Exporter] Write error");
+        recordCompletion(CompletionState::Failure);
         break;
       case http_client::SessionState::Cancelled:
         OTEL_INTERNAL_LOG_ERROR("[ES Log Exporter] (manually) cancelled");