Make Cancel actually terminate process_fn via SIGTERM

examples/midi_pitch_shifter/app.py

@@ -28,37 +28,38 @@ def process_fn(
     return output_midi_path
 
 # Build Gradio endpoint
-with gr.Blocks() as demo:
-    # Define input Gradio Components
-    input_components = [
-        gr.File(type="filepath",
-                label="Input Midi",
-                file_types=[".mid", ".midi"])
-        .harp_required(True),
-        gr.Slider(
-            minimum=-24,
-            maximum=24,
-            step=1,
-            value=7,
-            label="Pitch Shift (semitones)",
-            info="Controls the amount of pitch shift in semitones"
-        ),
-    ]
+if __name__ == "__main__":
+    with gr.Blocks() as demo:
+        # Define input Gradio Components
+        input_components = [
+            gr.File(type="filepath",
+                    label="Input Midi",
+                    file_types=[".mid", ".midi"])
+            .harp_required(True),
+            gr.Slider(
+                minimum=-24,
+                maximum=24,
+                step=1,
+                value=7,
+                label="Pitch Shift (semitones)",
+                info="Controls the amount of pitch shift in semitones"
+            ),
+        ]
 
-    # Define output Gradio Components
-    output_components = [
-        gr.File(type="filepath",
-                label="Output Midi",
-                file_types=[".mid", ".midi"])
-        .set_info("The pitch-shifted MIDI."),
-    ]
+        # Define output Gradio Components
+        output_components = [
+            gr.File(type="filepath",
+                    label="Output Midi",
+                    file_types=[".mid", ".midi"])
+            .set_info("The pitch-shifted MIDI."),
+        ]
 
-    # Build a HARP-compatible endpoint
-    app = build_endpoint(
-        model_card=model_card,
-        input_components=input_components,
-        output_components=output_components,
-        process_fn=process_fn,
-    )
+        # Build a HARP-compatible endpoint
+        app = build_endpoint(
+            model_card=model_card,
+            input_components=input_components,
+            output_components=output_components,
+            process_fn=process_fn,
+        )
 
-demo.queue().launch(share=True, show_error=False, pwa=True)
+    demo.queue().launch(share=True, show_error=False, pwa=True)

examples/midi_synthesizer/app.py

@@ -33,28 +33,29 @@ def process_fn(input_midi_path: str) -> str:
     return output_audio_path
 
 # Build Gradio endpoint
-with gr.Blocks() as demo:
-    # Define input Gradio Components
-    input_components = [
-        gr.File(type="filepath",
-                label="Input Midi",
-                file_types=[".mid", ".midi"])
-        .harp_required(True),
-    ]
-
-    # Define output Gradio Components
-    output_components = [
-        gr.Audio(type="filepath",
-                label="Output Audio")
-        .set_info("The synthesized audio."),
-    ]
-
-    # Build a HARP-compatible endpoint
-    app = build_endpoint(
-        model_card=model_card,
-        input_components=input_components,
-        output_components=output_components,
-        process_fn=process_fn,
-    )
-
-demo.queue().launch(share=True, show_error=False, pwa=True)
+if __name__ == "__main__":
+    with gr.Blocks() as demo:
+        # Define input Gradio Components
+        input_components = [
+            gr.File(type="filepath",
+                    label="Input Midi",
+                    file_types=[".mid", ".midi"])
+            .harp_required(True),
+        ]
+
+        # Define output Gradio Components
+        output_components = [
+            gr.Audio(type="filepath",
+                    label="Output Audio")
+            .set_info("The synthesized audio."),
+        ]
+
+        # Build a HARP-compatible endpoint
+        app = build_endpoint(
+            model_card=model_card,
+            input_components=input_components,
+            output_components=output_components,
+            process_fn=process_fn,
+        )
+
+    demo.queue().launch(share=True, show_error=False, pwa=True)

examples/pitch_shifter/app.py

@@ -38,35 +38,36 @@ def process_fn(
 
 
 # Build Gradio endpoint
-with gr.Blocks() as demo:
-    # Define input Gradio Components
-    input_components = [
-        gr.Audio(type="filepath",
-                 label="Input Audio A")
-        .harp_required(True),
-        gr.Slider(
-            minimum=-24,
-            maximum=24,
-            step=1,
-            value=7,
-            label="Pitch Shift (semitones)",
-            info="Controls the amount of pitch shift in semitones"
-        ),
-    ]
+if __name__ == "__main__":
+    with gr.Blocks() as demo:
+        # Define input Gradio Components
+        input_components = [
+            gr.Audio(type="filepath",
+                     label="Input Audio A")
+            .harp_required(True),
+            gr.Slider(
+                minimum=-24,
+                maximum=24,
+                step=1,
+                value=7,
+                label="Pitch Shift (semitones)",
+                info="Controls the amount of pitch shift in semitones"
+            ),
+        ]
 
-    # Define output Gradio Components
-    output_components = [
-        gr.Audio(type="filepath",
-                 label="Output Audio")
-        .set_info("The pitch-shifted audio."),
-    ]
+        # Define output Gradio Components
+        output_components = [
+            gr.Audio(type="filepath",
+                     label="Output Audio")
+            .set_info("The pitch-shifted audio."),
+        ]
 
-    # Build a HARP-compatible endpoint
-    app = build_endpoint(
-        model_card=model_card,
-        input_components=input_components,
-        output_components=output_components,
-        process_fn=process_fn,
-    )
+        # Build a HARP-compatible endpoint
+        app = build_endpoint(
+            model_card=model_card,
+            input_components=input_components,
+            output_components=output_components,
+            process_fn=process_fn,
+        )
 
-demo.queue().launch(share=True, show_error=False, pwa=True)
+    demo.queue().launch(share=True, show_error=False, pwa=True)

pyharp/core.py

@@ -2,9 +2,15 @@
 from dataclasses import dataclass, asdict
 from typing import List
 
+import multiprocessing as mp
+import threading
 import gradio as gr
 
 
+# "spawn" avoids deadlocks with CUDA/PyTorch libraries that "fork" can cause on Linux (HuggingFace Spaces)
+mp.set_start_method("spawn", force=True)
+
+
 __all__ = [
     'ModelCard',
     'build_endpoint'
@@ -174,8 +180,88 @@ def get_harp_component(gr_cmp: Component) -> HarpComponent:
 
     return harp_cmp
 
+def _worker_entry(fn, args, result_q):
+    import traceback
+    try:
+        result = fn(*args)
+        result_q.put(("ok", result))
+    except gr.Error as e:
+        traceback.print_exc()
+        result_q.put((
+            "gr_error",
+            (e.message, e.duration, e.visible, e.title),
+        ))
+    except Exception as e:
+        tb = traceback.format_exc()
+        result_q.put(("err", (str(e), tb)))
+
+class JobSupervisor:
+    """
+    Runs a callable in a subprocess and allows it to be cancelled or
+    timed out via SIGTERM, rather than running to completion server-side.
+    """
+
+    def __init__(self, timeout_s=900):
+        self.timeout_s = timeout_s
+        self._process = None
+        self._result_q = None
+        self._lock = threading.Lock()
+
+    def run(self, fn, *args):
+        self.cancel()  # single-flight: kill any previous job first
+
+        with self._lock:
+            self._result_q = mp.Queue()
+            self._process = mp.Process(
+                target=_worker_entry,
+                args=(fn, args, self._result_q),
+                daemon=True,
+            )
+            self._process.start()
+            process, result_q = self._process, self._result_q
+
+        process.join(self.timeout_s)
+
+        with self._lock:
+            if self._process is process and process.is_alive():
+                try:
+                    self._terminate("timeout")
+                except RuntimeError:
+                    pass  # sentinel pushed to result_q, handled below
+
+        status, payload = result_q.get()
+
+        with self._lock:
+            if self._process is process:
+                self._cleanup()
+
+        if status == "gr_error":
+            message, duration, visible, title = payload
+            raise gr.Error(message, duration=duration, visible=visible, title=title)
+        if status == "err":
+            short_msg, tb = payload
+            raise RuntimeError(f"{short_msg}\n\n{tb}")
+        return payload
+
+    def cancel(self):
+        with self._lock:
+            if self._process and self._process.is_alive():
+                self._terminate("cancelled")
+
+    def _terminate(self, reason):
+        self._process.terminate()
+        self._process.join()
+        if self._result_q is not None:
+            self._result_q.put(("gr_error", (f"Job {reason}.", 10, True, reason.capitalize())))
+        self._cleanup()
+        raise RuntimeError(f"Job {reason}")
+
+    def _cleanup(self):
+        self._process = None
+        self._result_q = None
+
 def build_endpoint(model_card: ModelCard, input_components: list, output_components: list,
-                   process_fn: callable) -> tuple:
+                   process_fn: callable, timeout_s: int = 900) -> tuple:
     """
     Builds a Gradio endpoint compatible with HARP.
 
@@ -197,6 +283,16 @@ def build_endpoint(model_card: ModelCard, input_components: list, output_compone
             - The function must accept the inputs in the same order as the inputs list.
             - The function must return the outputs in the same order as the outputs list,
               with a filepath string pointing to each output file.
+            - process_fn runs in a separate subprocess, so its arguments and
+              return values must be picklable (e.g. filepath strings, numbers,
+              booleans, JSON-serializable data). It cannot rely on gr.Progress
+              or other objects tied to the Gradio request context.
+            - If the Cancel button is pressed, or if process_fn runs longer
+              than timeout_s, the subprocess is killed (SIGTERM) and the job
+              is aborted.
+        timeout_s (int): Maximum time in seconds to let process_fn run before
+            it is forcibly killed. Defaults to 900 (15 minutes). Increase this
+            for models that need more time to process their inputs.
 
     Returns:
         app (dict): A dictionary containing:
@@ -231,10 +327,22 @@ def fetch_model_info():
         api_name="controls"
     )
 
+    # Supervise process_fn in a subprocess so it can be killed on cancel/timeout
+    supervisor = JobSupervisor(timeout_s=timeout_s)
+
+    def supervised_process(*args):
+        return supervisor.run(process_fn, *args)
+
+    def cancel_handler():
+        try:
+            supervisor.cancel()
+        except RuntimeError:
+            pass  # expected -- job was cancelled successfully
+
     # Create a button to begin processing
     process_button = gr.Button("Process")
     process_event = process_button.click(
-        fn=process_fn,
+        fn=supervised_process,
         inputs=input_components,
         outputs=output_components,
         api_name="process"
@@ -243,7 +351,7 @@ def fetch_model_info():
     # Create a button to cancel processing
     cancel_button = gr.Button("Cancel")
     cancel_button.click(
-        fn=lambda: None,
+        fn=cancel_handler,
         inputs=[],
         outputs=[],
         api_name="cancel",

setup.py

@@ -4,12 +4,12 @@
     name='pyharp',
     version='0.3.0',
     url='https://github.com/TEAMuP-dev/pyharp',
-    author='Frank Cwitkowitz, Christodoulos Benetatos, Hugo Flores García, Patrick O\'Reilly, Nathan Pruyne, and Aldo Aguilar',
+    author='Frank Cwitkowitz, Christodoulos Benetatos, Hugo Flores García, Patrick O\'Reilly, Nathan Pruyne, Aldo Aguilar and Saumya Pailwan',
     author_email='fcwitkow@ur.rochester.edu',
     description='',
     packages=find_packages(),
     install_requires=[
-        'gradio==5.28.0',
+        'gradio>=6.17.3,<7',
         'descript-audiotools',
         'symusic'
     ]