[Feature] python task logs print delayed (#1844)

* [Feature] python task logs print delayed
#1843 

dolphinscheduler-server/src/main/java/org/apache/dolphinscheduler/server/worker/task/AbstractCommandExecutor.java

@@ -30,10 +30,7 @@ import org.slf4j.Logger;
 import java.io.*;
 import java.lang.reflect.Field;
 import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Date;
-import java.util.List;
+import java.util.*;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
@@ -207,7 +204,14 @@ public abstract class AbstractCommandExecutor {
         // merge error information to standard output stream
         processBuilder.redirectErrorStream(true);
         // setting up user to run commands
-        processBuilder.command("sudo", "-u", tenantCode, commandInterpreter(), commandFile);
+        List<String> command = new LinkedList<>();
+        command.add("sudo");
+        command.add("-u");
+        command.add(tenantCode);
+        command.add(commandInterpreter());
+        command.addAll(commandOptions());
+        command.add(commandFile);
+        processBuilder.command(command);
 
         process = processBuilder.start();
 
@@ -559,7 +563,9 @@ public abstract class AbstractCommandExecutor {
         }
     }
 
-
+    protected List<String> commandOptions() {
+        return Collections.emptyList();
+    }
     protected abstract String buildCommandFilePath();
     protected abstract String commandInterpreter();
     protected abstract boolean checkFindApp(String line);

dolphinscheduler-server/src/main/java/org/apache/dolphinscheduler/server/worker/task/PythonCommandExecutor.java

@@ -26,6 +26,7 @@ import java.io.*;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
+import java.util.Collections;
 import java.util.Date;
 import java.util.List;
 import java.util.function.Consumer;
@@ -108,6 +109,16 @@ public class PythonCommandExecutor extends AbstractCommandExecutor {
         }
     }
 
+    /**
+     * get command options
+     * @return command options list
+     */
+    @Override
+    protected List<String> commandOptions() {
+        // unbuffered binary stdout and stderr
+        return Collections.singletonList("-u");
+    }
+
     /**
      * get python home
      * @return python home