fix: dispose window scheduler (influxdata#641)

Author: bednar

CHANGELOG.md

@@ -2,7 +2,8 @@
 
 ### Bug Fixes
 1. [#636](https://github.com/influxdata/influxdb-client-python/pull/636): Handle missing data in data frames
-2. [#638](https://github.com/influxdata/influxdb-client-python/pull/638), [#642](https://github.com/influxdata/influxdb-client-python/pull/642): Refactor DataFrame operations to avoid chained assignment and resolve FutureWarning in pandas, ensuring compatibility with pandas 3.0.
+1. [#638](https://github.com/influxdata/influxdb-client-python/pull/638), [#642](https://github.com/influxdata/influxdb-client-python/pull/642): Refactor DataFrame operations to avoid chained assignment and resolve FutureWarning in pandas, ensuring compatibility with pandas 3.0.
+1. [#641](https://github.com/influxdata/influxdb-client-python/pull/641): Correctly dispose ThreadPoolScheduler in WriteApi
 
 ### Documentation
 1. [#639](https://github.com/influxdata/influxdb-client-python/pull/639): Use Markdown for `README`

influxdb_client/client/write_api.py

@@ -250,16 +250,18 @@ def __init__(self,
         self._success_callback = kwargs.get('success_callback', None)
         self._error_callback = kwargs.get('error_callback', None)
         self._retry_callback = kwargs.get('retry_callback', None)
+        self._window_scheduler = None
 
         if self._write_options.write_type is WriteType.batching:
             # Define Subject that listen incoming data and produces writes into InfluxDB
             self._subject = Subject()
 
+            self._window_scheduler = ThreadPoolScheduler(1)
             self._disposable = self._subject.pipe(
                 # Split incoming data to windows by batch_size or flush_interval
                 ops.window_with_time_or_count(count=write_options.batch_size,
                                               timespan=timedelta(milliseconds=write_options.flush_interval),
-                                              scheduler=ThreadPoolScheduler(1)),
+                                              scheduler=self._window_scheduler),
                 # Map  window into groups defined by 'organization', 'bucket' and 'precision'
                 ops.flat_map(lambda window: window.pipe(
                     # Group window by 'organization', 'bucket' and 'precision'
@@ -440,6 +442,10 @@ def __del__(self):
                     )
                     break
 
+        if self._window_scheduler:
+            self._window_scheduler.executor.shutdown(wait=False)
+            self._window_scheduler = None
+
         if self._disposable:
             self._disposable = None
         pass
@@ -565,6 +571,7 @@ def __getstate__(self):
         # Remove rx
         del state['_subject']
         del state['_disposable']
+        del state['_window_scheduler']
         del state['_write_service']
         return state