Use simple print in tracker print function. (#6609)

python-package/xgboost/rabit.py

@@ -1,7 +1,6 @@
 # coding: utf-8
 # pylint: disable= invalid-name
 """Distributed XGBoost Rabit related API."""
-import sys
 import ctypes
 import pickle
 import numpy as np
@@ -79,8 +78,7 @@ def tracker_print(msg):
     if is_dist != 0:
         _check_call(_LIB.RabitTrackerPrint(c_str(msg)))
     else:
-        sys.stdout.write(msg)
-        sys.stdout.flush()
+        print(msg.strip(), flush=True)
 
 
 def get_processor_name():

python-package/xgboost/tracker.py

@@ -293,7 +293,7 @@ class RabitTracker(object):
             s = SlaveEntry(fd, s_addr)
             if s.cmd == 'print':
                 msg = s.sock.recvstr()
-                logging.info(msg.strip())
+                print(msg.strip(), flush=True)
                 continue
             if s.cmd == 'shutdown':
                 assert s.rank >= 0 and s.rank not in shutdown

tests/python/test_with_dask.py

@@ -867,7 +867,9 @@ class TestWithDask:
 
         test = "--gtest_filter=Quantile." + name
 
-        def runit(worker_addr: str, rabit_args: List[bytes]) -> subprocess.CompletedProcess:
+        def runit(
+            worker_addr: str, rabit_args: List[bytes]
+        ) -> subprocess.CompletedProcess:
             port_env = ''
             # setup environment for running the c++ part.
             for arg in rabit_args:
@@ -965,7 +967,9 @@ class TestWithDask:
         with tempfile.TemporaryDirectory() as tmpdir:
             path = os.path.join(tmpdir, 'log')
 
-            def sqr(labels: np.ndarray, predts: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
+            def sqr(
+                labels: np.ndarray, predts: np.ndarray
+            ) -> Tuple[np.ndarray, np.ndarray]:
                 with open(path, 'a') as fd:
                     print('Running sqr', file=fd)
                 grad = predts - labels