Added latch countdown on exception to address a potential leak in the implementation of #273

Author: sapessi

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/LambdaContainerHandler.java

@@ -195,9 +195,9 @@ public void setLogFormatter(LogFormatter<ContainerRequestType, ContainerResponse
      */
     public ResponseType proxy(RequestType request, Context context) {
         lambdaContext = context;
+        CountDownLatch latch = new CountDownLatch(1);
         try {
             SecurityContext securityContext = securityContextWriter.writeSecurityContext(request, context);
-            CountDownLatch latch = new CountDownLatch(1);
             ContainerRequestType containerRequest = requestReader.readRequest(request, securityContext, context, config);
             ContainerResponseType containerResponse = getContainerResponse(containerRequest, latch);
 
@@ -219,6 +219,9 @@ public ResponseType proxy(RequestType request, Context context) {
             return responseWriter.writeResponse(containerResponse, context);
         } catch (Exception e) {
             log.error("Error while handling request", e);
+            // release all waiting threads. This is safe here because if the count was already 0
+            // the latch will do nothing
+            latch.countDown();
 
             return exceptionHandler.handle(e);
         }