diff --git a/src/evox/monitors/evoxvis_monitor.py b/src/evox/monitors/evoxvis_monitor.py
index 59b73319..c31bab18 100644
--- a/src/evox/monitors/evoxvis_monitor.py
+++ b/src/evox/monitors/evoxvis_monitor.py
@@ -1,7 +1,10 @@
-import pyarrow as pa
+import tempfile
 import time
+from pathlib import Path
 from typing import Optional
-import warnings
+
+import jax.experimental.host_callback as hcb
+import pyarrow as pa
 
 
 class EvoXVisMonitor:
@@ -10,8 +13,15 @@ class EvoXVisMonitor:
 
     Parameters
     ----------
-    out_file
-        The path of the output file
+    base_filename
+        The base filename of the log file,
+        the final filename will be ``<base_filename>_<i>.arrow``,
+        where i is an incrementing number.
+    out_dir
+        This directory to write the log file into.
+        When set to None, the default directory will be used.
+        The default is ``<TEMP_DIR>/evox``,
+        on Windows, it's usually ``C:\TEMP\evox``, and on MacOS/Linux/BSDs it's ``/tmp/evox``.
     out_type
         "stream" or "file",
         For more information, please refer to https://arrow.apache.org/docs/python/ipc.html
@@ -28,13 +38,30 @@ class EvoXVisMonitor:
     """
 
     def __init__(
-        self, out_file: str, out_type: str = "file", batch_size: int = 64, compression: Optional[str] = None
+        self,
+        base_filename: str,
+        out_dir: str = None,
+        out_type: str = "file",
+        batch_size: int = 64,
+        compression: Optional[str] = None,
     ):
         self.get_time = time.perf_counter_ns
         self.batch_size = batch_size
         self.generation_counter = 0
         self.batch_record = []
-        self.sink = pa.OSFile(out_file, "wb")
+        if out_dir is None:
+            base_path = Path(tempfile.gettempdir()).joinpath("evox")
+        else:
+            base_path = Path(out_dir)
+        # if the log dir is not created, create it first
+        if not base_path.exists():
+            base_path.mkdir(parents=True, exist_ok=True)
+        # find the next available number
+        i = 0
+        while base_path.joinpath(f"{base_filename}_{i}.arrow").exists():
+            i += 1
+        path_str = str(base_path.joinpath(f"{base_filename}_{i}.arrow"))
+        self.sink = pa.OSFile(path_str, "wb")
         self.out_type = out_type
         self.compression = compression
 
@@ -43,6 +70,9 @@ def __init__(
         self.population_size = None
         self.population_dtype = None
         self.fitness_dtype = None
+
+        # the ec_schema is left empty until the first write
+        # then we can infer the schema
         self.ec_schema = None
         self.writer = None
 
@@ -59,6 +89,9 @@ def _write_batch(self):
         if len(self.generation) == 0:
             return
 
+        # first time writing the data
+        # infer the data schema
+        # and create the writer
         if self.ec_schema is None:
             population_byte_len = len(self.population[0])
             fitness_byte_len = len(self.fitness[0])
@@ -73,8 +106,8 @@ def _write_batch(self):
                 metadata={
                     "population_size": str(self.population_size),
                     "population_dtype": self.population_dtype,
-                    "fitness_dtype": self.fitness_dtype
-                }
+                    "fitness_dtype": self.fitness_dtype,
+                },
             )
 
             if self.out_type == "file":
@@ -84,6 +117,7 @@ def _write_batch(self):
                     options=pa.ipc.IpcWriteOptions(compression=self.compression),
                 )
 
+        # actually write the data to disk
         self.writer.write_batch(
             pa.record_batch(
                 [
@@ -97,20 +131,17 @@ def _write_batch(self):
         )
         self._reset_batch()
 
-    def record_pop(self, population):
+    def record_pop(self, population, transform=None):
         self.population.append(population.tobytes())
         self.population_size = population.shape[0]
         self.population_dtype = str(population.dtype)
-        # self.population_size.append(population.shape[0])
-        # self.population_dtype.append(str(population.dtype))
         return population
 
-    def record_fit(self, fitness):
+    def record_fit(self, fitness, transform=None):
         self.generation.append(self.generation_counter)
         self.timestamp.append(self.get_time())
         self.fitness.append(fitness.tobytes())
         self.fitness_dtype = str(fitness.dtype)
-        # self.fitness_dtype.append(str(fitness.dtype))
         self.generation_counter += 1
 
         if len(self.fitness) >= self.batch_size:
@@ -118,7 +149,11 @@ def record_fit(self, fitness):
 
         return fitness
 
+    def flush(self):
+        hcb.barrier_wait()
+
     def close(self):
+        self.flush()
         self._write_batch()
         self.writer.close()
         self.sink.close()