Fix #32068: delay release of Docker port

Author: LEDfan

src/main/java/eu/openanalytics/containerproxy/backend/docker/AbstractDockerBackend.java

@@ -44,6 +44,9 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
 import java.util.function.BiConsumer;
 
 
@@ -60,6 +63,8 @@ public abstract class AbstractDockerBackend extends AbstractContainerBackend {
     protected Integer portRangeFrom;
     protected Integer portRangeTo;
 
+    private final ScheduledExecutorService releasePortExecutor = Executors.newSingleThreadScheduledExecutor();
+
     @Override
     public void initialize() throws ContainerProxyException {
         super.initialize();
@@ -147,4 +152,8 @@ protected Map<RuntimeValueKey<?>, RuntimeValue> parseLabelsAsRuntimeValues(Strin
         return runtimeValues;
     }
 
+    protected void releasePort(String ownerId) {
+        releasePortExecutor.schedule(() -> portAllocator.release(ownerId), 10, TimeUnit.SECONDS);
+    }
+
 }

src/main/java/eu/openanalytics/containerproxy/backend/docker/DockerEngineBackend.java

@@ -222,7 +222,7 @@ protected void doStopProxy(Proxy proxy) throws Exception {
                 // ignore, container is currently being removed
             }
         }
-        portAllocator.release(proxy.getId());
+        releasePort(proxy.getId());
     }
 
     @Override

src/main/java/eu/openanalytics/containerproxy/backend/docker/DockerSwarmBackend.java

@@ -298,7 +298,7 @@ protected void doStopProxy(Proxy proxy) throws Exception {
                 }
             }
         }
-        portAllocator.release(proxy.getId());
+        releasePort(proxy.getId());
     }
 
     @Override