Catch exception in thread pool when migrate repos (#7320)

* Catch exception in thread pool when migrate repos

* Add comment and use different exit code

* Check exception only

---------

Co-authored-by: 杨赫然 <heran.yang@seafile.com>

scripts/migrate.py

@@ -16,10 +16,11 @@ from seafobj.objstore_factory import SeafObjStoreFactory
 logging.basicConfig(format='%(asctime)s %(message)s', level=logging.INFO)
 
 class Worker(Thread):
-    def __init__(self, do_work, task_queue):
+    def __init__(self, do_work, task_queue, pool):
         Thread.__init__(self)
         self.do_work = do_work
         self.task_queue = task_queue
+        self.pool = pool
 
     def run(self):
         while True:
@@ -29,6 +30,7 @@ class Worker(Thread):
                     break
                 self.do_work(task)
             except Exception as e:
+                self.pool.exception = e
                 logging.warning('Failed to execute task: %s' % e)
             finally:
                 self.task_queue.task_done()
@@ -37,11 +39,13 @@ class ThreadPool(object):
     def __init__(self, do_work, nworker=20):
         self.do_work = do_work
         self.nworker = nworker
+        # The pool's exception will be set when an exception occurs in the worker processing the migration object.
+        self.exception = None
         self.task_queue = queue.Queue(maxsize = 2000)
 
     def start(self):
         for i in range(self.nworker):
-            Worker(self.do_work, self.task_queue).start()
+            Worker(self.do_work, self.task_queue, self).start()
 
     def put_task(self, task):
         self.task_queue.put(task)
@@ -72,7 +76,6 @@ class ObjMigrateWorker(Thread):
         self.dest_objs = {}
         self.object_list_file_path = ''
         self.fd = None
-        self.exit_code = 0
         self.exception = None
         self.decrypt = decrypt
     
@@ -80,7 +83,6 @@ class ObjMigrateWorker(Thread):
         try:
             self._run()
         except Exception as e:
-            self.exit_code = 1
             self.exception = e
 
     def _run(self):
@@ -133,6 +135,7 @@ class ObjMigrateWorker(Thread):
         self.thread_pool.start()
         self.migrate()
         self.thread_pool.join()
+        self.exception = self.thread_pool.exception
         if self.object_list_file_path:
             self.fd.close()
         logging.info('Complete migrate [%s] object' % self.dtype)