From 5bc7de8ba3d3f25eb22029860cbea1ad38a88316 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Mon, 6 Feb 2023 14:21:12 -0500
Subject: [PATCH 1/3] Add test progress delete.

---
 .../long_callback/app_progress_delete.py      | 45 +++++++++++++++++++
 .../long_callback/test_basic_long_callback.py |  9 ++++
 2 files changed, 54 insertions(+)
 create mode 100644 tests/integration/long_callback/app_progress_delete.py

diff --git a/tests/integration/long_callback/app_progress_delete.py b/tests/integration/long_callback/app_progress_delete.py
new file mode 100644
index 0000000000..2fdf08af61
--- /dev/null
+++ b/tests/integration/long_callback/app_progress_delete.py
@@ -0,0 +1,45 @@
+from dash import Dash, Input, Output, State, html, clientside_callback
+import time
+
+from tests.integration.long_callback.utils import get_long_callback_manager
+
+long_callback_manager = get_long_callback_manager()
+handle = long_callback_manager.handle
+
+app = Dash(__name__, long_callback_manager=long_callback_manager)
+
+app.layout = html.Div(
+    [
+        html.Button("Start", id="start"),
+        html.Div(id="output"),
+        html.Div(id="progress-output"),
+        html.Div(0, id="progress-counter"),
+    ]
+)
+
+clientside_callback(
+    "function(_, previous) { return parseInt(previous) + 1;}",
+    Output("progress-counter", "children"),
+    Input("progress-output", "children"),
+    State("progress-counter", "children"),
+    prevent_initial_call=True,
+)
+
+
+@app.callback(
+    Output("output", "children"),
+    Input("start", "n_clicks"),
+    progress=Output("progress-output", "children"),
+    interval=200,
+    background=True,
+    prevent_initial_call=True,
+)
+def on_bg_progress(set_progress, _):
+    set_progress("start")
+    time.sleep(2)
+    set_progress("stop")
+    return "done"
+
+
+if __name__ == "__main__":
+    app.run_server(debug=True)
diff --git a/tests/integration/long_callback/test_basic_long_callback.py b/tests/integration/long_callback/test_basic_long_callback.py
index c2d04641d1..c82c64ab48 100644
--- a/tests/integration/long_callback/test_basic_long_callback.py
+++ b/tests/integration/long_callback/test_basic_long_callback.py
@@ -531,3 +531,12 @@ def test_lcbc013_unordered_state_input(dash_duo, manager):
         dash_duo.find_element("#click").click()
 
         dash_duo.wait_for_text_to_equal("#output", "stored")
+
+
+def test_lcbc014_progress_delete(dash_duo, manager):
+    with setup_long_callback_app(manager, "app_progress_delete") as app:
+        dash_duo.start_server(app)
+        dash_duo.find_element("#start").click()
+        dash_duo.wait_for_text_to_equal("#output", "done")
+
+        assert dash_duo.find_element("#progress-counter").text == "2"

From d291f59d538906e7887736908d84d4a313d145aa Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Mon, 6 Feb 2023 14:22:27 -0500
Subject: [PATCH 2/3] Delete progress after fetching it.

---
 dash/long_callback/managers/celery_manager.py    | 1 +
 dash/long_callback/managers/diskcache_manager.py | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/dash/long_callback/managers/celery_manager.py b/dash/long_callback/managers/celery_manager.py
index fba09af65c..b4e0165c8d 100644
--- a/dash/long_callback/managers/celery_manager.py
+++ b/dash/long_callback/managers/celery_manager.py
@@ -98,6 +98,7 @@ def get_progress(self, key):
         progress_key = self._make_progress_key(key)
         progress_data = self.handle.backend.get(progress_key)
         if progress_data:
+            self.handle.backend.delete(progress_key)
             return json.loads(progress_data)
 
         return None
diff --git a/dash/long_callback/managers/diskcache_manager.py b/dash/long_callback/managers/diskcache_manager.py
index c12bafeb98..fea69f37f5 100644
--- a/dash/long_callback/managers/diskcache_manager.py
+++ b/dash/long_callback/managers/diskcache_manager.py
@@ -127,7 +127,11 @@ def call_job_fn(self, key, job_fn, args, context):
 
     def get_progress(self, key):
         progress_key = self._make_progress_key(key)
-        return self.handle.get(progress_key)
+        progress_data = self.handle.get(progress_key)
+        if progress_data:
+            self.handle.delete(progress_key)
+
+        return progress_data
 
     def result_ready(self, key):
         return self.handle.get(key) is not None

From 19fa5c7fe0b4e69cf2ecf81f11b8f15e6751f297 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 7 Feb 2023 09:54:22 -0500
Subject: [PATCH 3/3] Update changelog.

---
 CHANGELOG.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1650c234ae..40ced996a5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,12 @@ All notable changes to `dash` will be documented in this file.
 This project adheres to [Semantic Versioning](https://semver.org/).
 
 
+## [UNRELEASED]
+
+## Fixed
+
+- [#2415](https://github.com/plotly/dash/pull/2415) Fix background callbacks progress not deleted after fetch.
+
 ## [2.8.1] - 2023-01-30
 
 ## Fixed