Fixed concurrency issues on high load

@@ -29,6 +29,7 @@ import org.thingsboard.server.kafka.*;
 import javax.annotation.PostConstruct;
 import javax.annotation.PreDestroy;
 import java.util.concurrent.ExecutorService;
+import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
@@ -67,7 +68,7 @@ public class RemoteTransportApiService {
 
     @PostConstruct
     public void init() {
-        this.transportCallbackExecutor = new ThreadPoolExecutor(0, 100, 60L, TimeUnit.SECONDS, new SynchronousQueue<>());
+        this.transportCallbackExecutor = new ThreadPoolExecutor(0, 100, 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<>());
 
         TBKafkaProducerTemplate.TBKafkaProducerTemplateBuilder<TransportApiResponseMsg> responseBuilder = TBKafkaProducerTemplate.builder();
         responseBuilder.settings(kafkaSettings);

@@ -32,6 +32,7 @@ import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.ThreadPoolExecutor;
@@ -277,7 +278,7 @@ public abstract class AbstractTransportService implements TransportService {
             new TbRateLimits(perDevicesLimitsConf);
         }
         this.schedulerExecutor = Executors.newSingleThreadScheduledExecutor();
-        this.transportCallbackExecutor = new ThreadPoolExecutor(0, 20, 60L, TimeUnit.SECONDS, new SynchronousQueue<>());
+        this.transportCallbackExecutor = new ThreadPoolExecutor(0, 20, 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<>());
         this.schedulerExecutor.scheduleAtFixedRate(this::checkInactivityAndReportActivity, sessionReportTimeout, sessionReportTimeout, TimeUnit.MILLISECONDS);
     }
 

@@ -31,7 +31,9 @@ import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.LinkedBlockingDeque;
+import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -70,7 +72,7 @@ public abstract class AbstractBufferedRateExecutor<T extends AsyncTask, F extend
         this.concurrencyLimit = concurrencyLimit;
         this.queue = new LinkedBlockingDeque<>(queueLimit);
         this.dispatcherExecutor = Executors.newFixedThreadPool(dispatcherThreads);
-        this.callbackExecutor = Executors.newFixedThreadPool(callbackThreads);
+        this.callbackExecutor = new ThreadPoolExecutor(callbackThreads, 50, 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<>());
         this.timeoutExecutor = Executors.newSingleThreadScheduledExecutor();
         this.perTenantLimitsEnabled = perTenantLimitsEnabled;
         this.perTenantLimitsConfiguration = perTenantLimitsConfiguration;