Fix thread "leak"

src/psij/executors/batch/batch_scheduler_executor.py

@@ -3,6 +3,7 @@
 import subprocess
 import time
 import traceback
+import weakref
 from abc import abstractmethod
 from datetime import timedelta
 from pathlib import Path
@@ -639,45 +640,51 @@ def __init__(self, name: str, config: BatchSchedulerExecutorConfig,
         self.name = name
         self.daemon = True
         self.config = config
-        self.executor = executor
+        self.done = False
+        self.executor = weakref.ref(executor, self._stop)
         # native_id -> job
         self._jobs: Dict[str, List[Job]] = {}
         # counts consecutive errors while invoking qstat or equivalent
         self._poll_error_count = 0
         self._jobs_lock = RLock()
 
     def run(self) -> None:
-        logger.debug('Executor %s: queue poll thread started', self.executor)
+        logger.debug('Executor %s: queue poll thread started', self.executor())
         time.sleep(self.config.initial_queue_polling_delay)
-        while True:
+        while not self.done:
             self._poll()
             time.sleep(self.config.queue_polling_interval)
 
+    def _stop(self, exec: object) -> None:
+        self.done = True
+
     def _poll(self) -> None:
+        exec = self.executor()
+        if exec is None:
+            return
         with self._jobs_lock:
             if len(self._jobs) == 0:
                 return
             jobs_copy = dict(self._jobs)
         logger.info('Polling for %s jobs', len(jobs_copy))
         try:
-            out = self.executor._run_command(self.executor.get_status_command(jobs_copy.keys()))
+            if exec:
+                out = exec._run_command(exec.get_status_command(jobs_copy.keys()))
         except subprocess.CalledProcessError as ex:
             out = ex.output
             exit_code = ex.returncode
         except Exception as ex:
-            self._handle_poll_error(True,
-                                    ex,
+            self._handle_poll_error(exec, True, ex,
                                     f'Failed to poll for job status: {traceback.format_exc()}')
             return
         else:
             exit_code = 0
             self._poll_error_count = 0
         logger.debug('Output from status command: %s', out)
         try:
-            status_map = self.executor.parse_status_output(exit_code, out)
+            status_map = exec.parse_status_output(exit_code, out)
         except Exception as ex:
-            self._handle_poll_error(False,
-                                    ex,
+            self._handle_poll_error(exec, False, ex,
                                     f'Failed to poll for job status: {traceback.format_exc()}')
             return
         try:
@@ -689,21 +696,22 @@ def _poll(self) -> None:
                                        message='Failed to update job status: %s' %
                                                traceback.format_exc())
                 for job in job_list:
-                    self.executor._set_job_status(job, status)
+                    exec._set_job_status(job, status)
                 if status.state.final:
                     with self._jobs_lock:
                         del self._jobs[native_id]
         except Exception as ex:
             msg = traceback.format_exc()
-            self._handle_poll_error(True, ex, 'Error updating job statuses {}'.format(msg))
+            self._handle_poll_error(exec, True, ex, 'Error updating job statuses {}'.format(msg))
 
     def _get_job_status(self, native_id: str, status_map: Dict[str, JobStatus]) -> JobStatus:
         if native_id in status_map:
             return status_map[native_id]
         else:
             return JobStatus(JobState.COMPLETED)
 
-    def _handle_poll_error(self, immediate: bool, ex: Exception, msg: str) -> None:
+    def _handle_poll_error(self, exec: BatchSchedulerExecutor, immediate: bool, ex: Exception,
+                           msg: str) -> None:
         logger.warning('Polling error: %s', msg)
         self._poll_error_count += 1
         if immediate or (self._poll_error_count > self.config.queue_polling_error_threshold):
@@ -720,7 +728,7 @@ def _handle_poll_error(self, immediate: bool, ex: Exception, msg: str) -> None:
                 self._jobs.clear()
             for job_list in jobs_copy.values():
                 for job in job_list:
-                    self.executor._set_job_status(job, JobStatus(JobState.FAILED, message=msg))
+                    exec._set_job_status(job, JobStatus(JobState.FAILED, message=msg))
 
     def register_job(self, job: Job) -> None:
         assert job.native_id