diff --git a/include/comm/ClientServer.h b/include/comm/ClientServer.h
index 04bd9eb..ebcd735 100644
--- a/include/comm/ClientServer.h
+++ b/include/comm/ClientServer.h
@@ -44,9 +44,6 @@ namespace FMI::Comm {
         //! Uploads objects and keeps track of them.
         virtual void upload(channel_data buf, std::string name);
 
-        //! List all the currently existing objects, needs to be implemented by channels. Needed by some collectives that check for the existence of files, but do not care about their content.
-        virtual std::vector<std::string> get_object_names() = 0;
-
         //! Delete the object with the given name, needs to be implemented by channels.
         virtual void delete_object(std::string name) = 0;
 
diff --git a/include/comm/Redis.h b/include/comm/Redis.h
index 16edc56..f3bbf3c 100644
--- a/include/comm/Redis.h
+++ b/include/comm/Redis.h
@@ -20,8 +20,6 @@ namespace FMI::Comm {
 
         void delete_object(std::string name) override;
 
-        std::vector<std::string> get_object_names() override;
-
         double get_latency(Utils::peer_num producer, Utils::peer_num consumer, std::size_t size_in_bytes) override;
 
         double get_price(Utils::peer_num producer, Utils::peer_num consumer, std::size_t size_in_bytes) override;
diff --git a/include/comm/S3.h b/include/comm/S3.h
index cb694ab..dbd34c4 100644
--- a/include/comm/S3.h
+++ b/include/comm/S3.h
@@ -22,8 +22,6 @@ namespace FMI::Comm {
 
         void delete_object(std::string name) override;
 
-        std::vector<std::string> get_object_names() override;
-
         double get_latency(Utils::peer_num producer, Utils::peer_num consumer, std::size_t size_in_bytes) override;
 
         double get_price(Utils::peer_num producer, Utils::peer_num consumer, std::size_t size_in_bytes) override;
diff --git a/src/comm/ClientServer.cpp b/src/comm/ClientServer.cpp
index ef9f5c8..8776944 100644
--- a/src/comm/ClientServer.cpp
+++ b/src/comm/ClientServer.cpp
@@ -50,11 +50,16 @@ void FMI::Comm::ClientServer::barrier() {
     upload({&b, sizeof(b)}, file_name);
     unsigned int elapsed_time = 0;
     while (elapsed_time < max_timeout) {
-        auto objects = get_object_names();
-        auto has_barrier_suffix = [barrier_suffix] (const std::string& s){return s.size() > barrier_suffix.size() &&
-                                                    s.compare(s.size() - barrier_suffix.size(), barrier_suffix.size(), barrier_suffix) == 0 ;};
-        auto num_arrived = std::count_if(objects.begin(), objects.end(), has_barrier_suffix);
-        if (num_arrived >= num_peers) {
+        bool all_arrived = true;
+        for (int i = 0; i < num_peers; i++) {
+            char arrived = 0;
+            std::string expected_name = comm_name + std::to_string(i) + barrier_suffix;
+            if (!download_object({&arrived, sizeof(arrived)}, expected_name)) {
+                all_arrived = false;
+                break;
+            }
+        }
+        if (all_arrived) {
             return;
         } else {
             elapsed_time += timeout;
diff --git a/src/comm/Redis.cpp b/src/comm/Redis.cpp
index 74e36db..d1ef1b9 100644
--- a/src/comm/Redis.cpp
+++ b/src/comm/Redis.cpp
@@ -59,16 +59,6 @@ void FMI::Comm::Redis::delete_object(std::string name) {
     freeReplyObject(reply);
 }
 
-std::vector<std::string> FMI::Comm::Redis::get_object_names() {
-    std::vector<std::string> keys;
-    std::string command = "KEYS *";
-    auto* reply = (redisReply*) redisCommand(context, command.c_str());
-    for (int i = 0; i < reply->elements; i++) {
-        keys.emplace_back(reply->element[i]->str);
-    }
-    return keys;
-}
-
 double FMI::Comm::Redis::get_latency(Utils::peer_num producer, Utils::peer_num consumer, std::size_t size_in_bytes) {
     double agg_bandwidth = std::min(producer * consumer * bandwidth_single, bandwidth_multiple);
     double trans_time = producer * consumer * ((double) size_in_bytes / 1000000.) / agg_bandwidth;
diff --git a/src/comm/S3.cpp b/src/comm/S3.cpp
index 7dde3a5..e7cb7a3 100644
--- a/src/comm/S3.cpp
+++ b/src/comm/S3.cpp
@@ -4,7 +4,6 @@
 #include <aws/s3/model/PutObjectRequest.h>
 #include <aws/s3/model/GetObjectRequest.h>
 #include <aws/s3/model/DeleteObjectRequest.h>
-#include <aws/s3/model/ListObjectsRequest.h>
 #include <cmath>
 
 char TAG[] = "S3Client";
@@ -70,22 +69,6 @@ void FMI::Comm::S3::delete_object(std::string name) {
     }
 }
 
-std::vector<std::string> FMI::Comm::S3::get_object_names() {
-    std::vector<std::string> object_names;
-    Aws::S3::Model::ListObjectsRequest request;
-    request.WithBucket(bucket_name);
-    auto outcome = client->ListObjects(request);
-    if (outcome.IsSuccess()) {
-        auto objects = outcome.GetResult().GetContents();
-        for (auto& object : objects) {
-            object_names.push_back(object.GetKey());
-        }
-    } else {
-        BOOST_LOG_TRIVIAL(error) << "Error when listing objects from S3: " << outcome.GetError();
-    }
-    return object_names;
-}
-
 double FMI::Comm::S3::get_latency(Utils::peer_num producer, Utils::peer_num consumer, std::size_t size_in_bytes) {
     double fixed_overhead = overhead;
     double waiting_time = (double) timeout / 2.;