recreate session for both session error and connection exception

client/src/main/java/com/vesoft/nebula/client/graph/NebulaSession.java

@@ -73,7 +73,9 @@ public void release() {
             connection.signout(sessionID);
             connection.close();
         } catch (Exception e) {
-            log.warn("release session failed, " + e.getMessage());
+            // not print the warn to avoid confuse for session and connect,
+            // when connection is broken, release will failed, just make connection as null.
+            // log.warn("release session failed, " + e.getMessage());
         }
         connection = null;
     }

client/src/main/java/com/vesoft/nebula/client/graph/SessionPool.java

@@ -5,6 +5,8 @@
 
 package com.vesoft.nebula.client.graph;
 
+import static com.vesoft.nebula.client.graph.exception.IOErrorException.E_CONNECT_BROKEN;
+
 import com.alibaba.fastjson.JSON;
 import com.vesoft.nebula.ErrorCode;
 import com.vesoft.nebula.client.graph.data.HostAddress;
@@ -138,22 +140,27 @@ public ResultSet execute(String stmt) throws IOErrorException,
         stmtCheck(stmt);
         checkSessionPool();
         NebulaSession nebulaSession = getSession();
-        ResultSet resultSet;
-        try {
-            resultSet = nebulaSession.execute(stmt);
-
-            // re-execute for session error
-            if (isSessionError(resultSet)) {
+        ResultSet resultSet = null;
+        int tryTimes = 3;
+        while (tryTimes-- > 0) {
+            try {
+                resultSet = nebulaSession.execute(stmt);
+                if (!isSessionError(resultSet)) {
+                    useSpace(nebulaSession, resultSet);
+                    return resultSet;
+                } else {
+                    throw new IOErrorException(E_CONNECT_BROKEN, resultSet.getErrorMessage());
+                }
+            } catch (IOErrorException e) {
                 nebulaSession.release();
                 sessionList.remove(nebulaSession);
-                nebulaSession = getSession();
-                resultSet = nebulaSession.execute(stmt);
+                if (tryTimes > 0) {
+                    nebulaSession = createSessionObject(SessionState.USED);
+                } else {
+                    throw e;
+                }
             }
-        } catch (IOErrorException e) {
-            useSpace(nebulaSession, null);
-            throw e;
         }
-        useSpace(nebulaSession, resultSet);
         return resultSet;
     }
 
@@ -339,7 +346,8 @@ public HostAddress getAddress() {
     private void useSpace(NebulaSession nebulaSession, ResultSet resultSet)
             throws IOErrorException {
         if (resultSet == null) {
-            releaseSession(nebulaSession);
+            nebulaSession.release();
+            sessionList.remove(nebulaSession);
             return;
         }
         // space has been drop, close the SessionPool

client/src/test/java/com/vesoft/nebula/client/graph/data/TestDataFromServer.java

@@ -45,7 +45,7 @@ public void setUp() throws Exception {
         NebulaPoolConfig nebulaPoolConfig = new NebulaPoolConfig();
         nebulaPoolConfig.setMaxConnSize(1);
         Assert.assertTrue(pool.init(Arrays.asList(new HostAddress(
-                "127.0.0.1", 9670)),
+                "127.0.0.1", 9669)),
                 nebulaPoolConfig));
         session = pool.getSession("root", "nebula", true);
         ResultSet resp = session.execute("CREATE SPACE IF NOT EXISTS test_data"
@@ -502,16 +502,13 @@ public void tesDataset() {
             Collections.sort(pathStrings);
             String listString = String.join(", ",
                     pathStrings);
-
-            String expectString = "ColumnName: [p],"
-                    + " Values: [(\"a\" )-[:like@0{}]->(\"f\" )<-[:like@0{}]-(\"c\" )], "
-                    + "ColumnName: [p],"
-                    + " Values: [(\"a\" )-[:like@0{}]->(\"g\" )-[:like@0{}]->(\"c\" )], "
-                    + "ColumnName: [p],"
-                    + " Values: [(\"a\" )<-[:like@0{}]-(\"b\" )<-[:like@0{}]-(\"c\" )], "
-                    + "ColumnName: [p],"
-                    + " Values: [(\"a\" )<-[:like@0{}]-(\"d\" )-[:like@0{}]->(\"c\" )]";
-
+            String expectString = "ColumnName: [p], Values: [(\"a\" :player {})-[:like@0{}]->"
+                    + "(\"f\" :player {})<-[:like@0{}]-(\"c\" :player {})], ColumnName: [p], "
+                    + "Values: [(\"a\" :player {})-[:like@0{}]->(\"g\" :player {})-[:like@0{}]->"
+                    + "(\"c\" :player {})], ColumnName: [p], Values: [(\"a\" :player {})"
+                    + "<-[:like@0{}]-(\"b\" :player {})<-[:like@0{}]-(\"c\" :player {})], "
+                    + "ColumnName: [p], Values: [(\"a\" :player {})<-[:like@0{}]-(\"d\" :player {})"
+                    + "-[:like@0{}]->(\"c\" :player {})]";
             Assert.assertEquals(expectString, listString);
         } catch (IOErrorException
                 | InterruptedException e) {

client/src/test/java/com/vesoft/nebula/client/graph/net/TestSessionPool.java

@@ -324,4 +324,51 @@ public void testReleaseBrokenSession() {
         }
     }
 
+    @Test
+    public void testBrokenConnectionForSession() {
+        List<HostAddress> addresses = Arrays.asList(new HostAddress(ip, 9669));
+        SessionPoolConfig config = new SessionPoolConfig(addresses, "space_for_session_pool",
+                "root", "nebula");
+        SessionPool sessionPool = new SessionPool(config);
+        assert sessionPool.init();
+
+        Runtime runtime = Runtime.getRuntime();
+        try {
+            try {
+                ResultSet resultSet = sessionPool.execute("SHOW SPACES;");
+                if (!resultSet.isSucceeded()) {
+                    System.out.println("show spaces failed, ErrorCode:"
+                            + resultSet.getErrorCode() + " ErrorMessage："
+                            + resultSet.getErrorMessage());
+                }
+            } catch (Exception e) {
+                e.printStackTrace();
+                assert false;
+            }
+
+            String cmd = "docker restart nebula-docker-compose_graphd0_1";
+            Process p = runtime.exec(cmd);
+            p.waitFor(5, TimeUnit.SECONDS);
+            ProcessUtil.printProcessStatus(cmd, p);
+            Thread.sleep(30000);
+
+            try {
+                ResultSet resultSet = sessionPool.execute("SHOW SPACES;");
+                if (!resultSet.isSucceeded()) {
+                    System.out.println("show spaces failed, ErrorCode:"
+                            + resultSet.getErrorCode() + " ErrorMessage："
+                            + resultSet.getErrorMessage());
+                }
+            } catch (Exception e) {
+                e.printStackTrace();
+                assert false;
+            }
+            sessionPool.close();
+        } catch (Exception e) {
+            e.printStackTrace();
+            Assert.assertFalse(e.getMessage(), false);
+        }
+
+    }
+
 }