Merge pull request #2473 from plotly/fix-2221

Add callback id to long callback key generation.

Author: T4rk1n

CHANGELOG.md

@@ -8,6 +8,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 - [#2479](https://github.com/plotly/dash/pull/2479) Fix `KeyError` "Callback function not found for output [...], , perhaps you forgot to prepend the '@'?" issue when using duplicate callbacks targeting the same output. This issue would occur when the app is restarted or when running with multiple `gunicorn` workers.
 - [#2471](https://github.com/plotly/dash/pull/2471) Fix `allow_duplicate` output with clientside callback, fix [#2467](https://github.com/plotly/dash/issues/2467)
+- [#2473](https://github.com/plotly/dash/pull/2473) Fix background callbacks with different outputs but same function, fix [#2221](https://github.com/plotly/dash/issues/2221)
 
 ## [2.9.1] - 2023-03-17
 

dash/_callback.py

@@ -316,7 +316,9 @@ def wrap_func(func):
 
         if long is not None:
             long_key = BaseLongCallbackManager.register_func(
-                func, long.get("progress") is not None
+                func,
+                long.get("progress") is not None,
+                callback_id,
             )
 
         @wraps(func)

dash/long_callback/managers/__init__.py

@@ -36,7 +36,7 @@ def terminate_unhealthy_job(self, job):
     def job_running(self, job):
         raise NotImplementedError
 
-    def make_job_fn(self, fn, progress):
+    def make_job_fn(self, fn, progress, key=None):
         raise NotImplementedError
 
     def call_job_fn(self, key, job_fn, args, context):
@@ -76,11 +76,11 @@ def build_cache_key(self, fn, args, cache_args_to_ignore):
         return hashlib.sha1(str(hash_dict).encode("utf-8")).hexdigest()
 
     def register(self, key, fn, progress):
-        self.func_registry[key] = self.make_job_fn(fn, progress)
+        self.func_registry[key] = self.make_job_fn(fn, progress, key)
 
     @staticmethod
-    def register_func(fn, progress):
-        key = BaseLongCallbackManager.hash_function(fn)
+    def register_func(fn, progress, callback_id):
+        key = BaseLongCallbackManager.hash_function(fn, callback_id)
         BaseLongCallbackManager.functions.append(
             (
                 key,
@@ -99,7 +99,9 @@ def _make_progress_key(key):
         return key + "-progress"
 
     @staticmethod
-    def hash_function(fn):
+    def hash_function(fn, callback_id=""):
         fn_source = inspect.getsource(fn)
         fn_str = fn_source
-        return hashlib.sha1(fn_str.encode("utf-8")).hexdigest()
+        return hashlib.sha1(
+            callback_id.encode("utf-8") + fn_str.encode("utf-8")
+        ).hexdigest()

dash/long_callback/managers/celery_manager.py

@@ -1,6 +1,4 @@
 import json
-import inspect
-import hashlib
 import traceback
 from contextvars import copy_context
 
@@ -78,8 +76,8 @@ def job_running(self, job):
             "PROGRESS",
         )
 
-    def make_job_fn(self, fn, progress):
-        return _make_job_fn(fn, self.handle, progress)
+    def make_job_fn(self, fn, progress, key=None):
+        return _make_job_fn(fn, self.handle, progress, key)
 
     def get_task(self, job):
         if job:
@@ -127,15 +125,10 @@ def get_result(self, key, job):
         return result
 
 
-def _make_job_fn(fn, celery_app, progress):
+def _make_job_fn(fn, celery_app, progress, key):
     cache = celery_app.backend
 
-    # Hash function source and module to create a unique (but stable) celery task name
-    fn_source = inspect.getsource(fn)
-    fn_str = fn_source
-    fn_hash = hashlib.sha1(fn_str.encode("utf-8")).hexdigest()
-
-    @celery_app.task(name=f"long_callback_{fn_hash}")
+    @celery_app.task(name=f"long_callback_{key}")
     def job_fn(result_key, progress_key, user_callback_args, context=None):
         def _set_progress(progress_value):
             if not isinstance(progress_value, (list, tuple)):

dash/long_callback/managers/diskcache_manager.py

@@ -107,7 +107,7 @@ def job_running(self, job):
             return proc.status() != psutil.STATUS_ZOMBIE
         return False
 
-    def make_job_fn(self, fn, progress):
+    def make_job_fn(self, fn, progress, key=None):
         return _make_job_fn(fn, self.handle, progress)
 
     def clear_cache_entry(self, key):

tests/integration/long_callback/app_diff_outputs.py

@@ -0,0 +1,36 @@
+from dash import Dash, Input, Output, html
+
+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("click 1", id="button-1"),
+        html.Button("click 2", id="button-2"),
+        html.Div(id="output-1"),
+        html.Div(id="output-2"),
+    ]
+)
+
+
+def gen_callback(index):
+    @app.callback(
+        Output(f"output-{index}", "children"),
+        Input(f"button-{index}", "n_clicks"),
+        background=True,
+        prevent_initial_call=True,
+    )
+    def callback_name(_):
+        return f"Clicked on {index}"
+
+
+for i in range(1, 3):
+    gen_callback(i)
+
+
+if __name__ == "__main__":
+    app.run_server(debug=True)

tests/integration/long_callback/test_basic_long_callback.py

@@ -547,3 +547,12 @@ def test_lcbc014_progress_delete(dash_duo, manager):
         dash_duo.wait_for_text_to_equal("#output", "done")
 
         assert dash_duo.find_element("#progress-counter").text == "2"
+
+
+def test_lcbc015_diff_outputs_same_func(dash_duo, manager):
+    with setup_long_callback_app(manager, "app_diff_outputs") as app:
+        dash_duo.start_server(app)
+
+        for i in range(1, 3):
+            dash_duo.find_element(f"#button-{i}").click()
+            dash_duo.wait_for_text_to_equal(f"#output-{i}", f"Clicked on {i}")