diff --git a/dnet-ariadneplus/src/main/java/eu/dnetlib/ariadneplus/workflows/nodes/PublishGraphDBJobNode.java b/dnet-ariadneplus/src/main/java/eu/dnetlib/ariadneplus/workflows/nodes/PublishGraphDBJobNode.java
index b7197c8..19af614 100644
--- a/dnet-ariadneplus/src/main/java/eu/dnetlib/ariadneplus/workflows/nodes/PublishGraphDBJobNode.java
+++ b/dnet-ariadneplus/src/main/java/eu/dnetlib/ariadneplus/workflows/nodes/PublishGraphDBJobNode.java
@@ -14,8 +14,11 @@ import org.apache.http.HttpResponse;
 import org.apache.http.NameValuePair;
 import org.apache.http.client.HttpClient;
 import org.apache.http.client.entity.UrlEncodedFormEntity;
+import org.apache.http.client.methods.CloseableHttpResponse;
 import org.apache.http.client.methods.HttpPost;
+import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.HttpClients;
+import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
 import org.apache.http.message.BasicNameValuePair;
 import org.springframework.beans.factory.annotation.Autowired;
 
@@ -46,6 +49,7 @@ public class PublishGraphDBJobNode extends AsyncJobNode {
 
 	//for parallel requests to the publisher endpoint
 	private int nThreads = 5;
+	private int nTasks = 150;
 	private ExecutorService executorService = Executors.newFixedThreadPool(nThreads);
 	private List<Future<Integer>> resList = Lists.newArrayList();
 
@@ -57,19 +61,39 @@ public class PublishGraphDBJobNode extends AsyncJobNode {
 
 		int countAll = 0;
 		int countOk = 0;
+		int partial = 0;
 		Map<Integer, Integer> errors = Maps.newHashMap();
-		log.info("Publish endpoint: " + getPublishEndpoint());
+		log.info("Publisher endpoint: " + getPublisherEndpoint());
+		PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
+		cm.setMaxTotal(nThreads);
+
+		CloseableHttpClient client = HttpClients.custom().setConnectionManager(cm).build();
+		//need to slow down the producer to avoid OOM errors due to many tasks in the queue of the executor
+		//see for example here: https://stackoverflow.com/questions/42108351/executorservice-giving-out-of-memory-error
+		//let's stop and wait after submission of nLatch tasks
 		for (String record : getResultSetClient().iter(rsIn, String.class)) {
 			countAll++;
+			if(partial == nTasks) {
+				log.debug("Waiting for tasks to complete before resubmitting to executor (countAll = "+countAll+") . . . ");
+				log.debug("Getting replies");
+				long startWait = System.currentTimeMillis();
+				for(Future<Integer> res : resList){
+					if(res.get() == 200) countOk++;
+				}
+				resList.clear();
+				partial = 0;
+				log.debug(". . . Ready to submit again after "+(System.currentTimeMillis() - startWait)+" ms" );
+			}
+			partial++;
 			Future<Integer> res = executorService.submit( () -> {
+				CloseableHttpResponse responsePOST = null;
 				try {
 					HttpPost post = new HttpPost(getPublishEndpoint());
 					List<NameValuePair> params = Lists.newArrayList();
 					params.add(new BasicNameValuePair("record", record));
 					UrlEncodedFormEntity ent =  new UrlEncodedFormEntity(params, "UTF-8");
 					post.setEntity(ent);
-					HttpClient client = HttpClients.createDefault();
-					HttpResponse responsePOST = client.execute(post);
+					responsePOST = client.execute(post);
 					int statusCode = responsePOST.getStatusLine().getStatusCode();
 					switch (statusCode) {
 					case 200:
@@ -87,6 +111,9 @@ public class PublishGraphDBJobNode extends AsyncJobNode {
 					e.printStackTrace();
 					errors.merge(-1, 1, Integer::sum);
 				}
+				finally{
+					if(responsePOST != null) responsePOST.close();
+				}
 				return -1;
 			});
 			resList.add(res);
@@ -98,6 +125,7 @@ public class PublishGraphDBJobNode extends AsyncJobNode {
 		for(Future<Integer> res : resList){
 			if(res.get() == 200) countOk++;
 		}
+		client.close();
 		log.info(String.format("Got all responses. Ok responses: %s/%s", countOk, countAll));
 
 		env.setAttribute(WorkflowsConstants.MAIN_LOG_PREFIX + "countOk", countOk);
@@ -108,14 +136,14 @@ public class PublishGraphDBJobNode extends AsyncJobNode {
 		if (!errors.isEmpty()) {
 			log.warn("Problems in publishing: "+countOk+"/"+countAll+" see error maps for details");
 		}
-		if(countAll == 0) log.warn("0 resources to publish");
-		
-		env.setAttribute(WorkflowsConstants.MAIN_LOG_PREFIX + "countOk", countOk);
-		env.setAttribute(WorkflowsConstants.MAIN_LOG_PREFIX + "countAll", countAll);
-		env.setAttribute(WorkflowsConstants.MAIN_LOG_PREFIX + "errorsMap", new Gson().toJson(errors));
+		if(countAll == 0) {
+			log.warn("0 resources to publish");
+			cm.shutdown();
+		}
 		
 		if (countOk > 0) {
 			log.info("Feed provenance endpoint: " + getProvenanceFeedEndpoint());
+			CloseableHttpResponse responsePOST = null;
 			try {
 				HttpPost post = new HttpPost(getProvenanceFeedEndpoint());
 				List<NameValuePair> params = Lists.newArrayList();
@@ -124,8 +152,7 @@ public class PublishGraphDBJobNode extends AsyncJobNode {
 				params.add(new BasicNameValuePair("datasourceApi", datasourceInterfaceValue));
 				UrlEncodedFormEntity ent =  new UrlEncodedFormEntity(params, "UTF-8");
 				post.setEntity(ent);
-				HttpClient client = HttpClients.createDefault();
-				HttpResponse responsePOST = client.execute(post);
+				responsePOST = client.execute(post);
 				int statusCode = responsePOST.getStatusLine().getStatusCode();
 				switch (statusCode) {
 				case 200:
@@ -141,8 +168,12 @@ public class PublishGraphDBJobNode extends AsyncJobNode {
 			catch (IOException e) {
 				log.error("error feeding provenance ", e);
 			}
+			finally{
+				if(responsePOST != null) responsePOST.close();
+				cm.shutdown();
+			}
 		}
-		
+
 		return Arc.DEFAULT_ARC;
 	}