Multithreading examples (#1210)

Author: sfc-gh-dmatthews

python/concept-source/multithreading-expose-context.py

@@ -0,0 +1,38 @@
+import streamlit as st
+from streamlit.runtime.scriptrunner import add_script_run_ctx, get_script_run_ctx
+import time
+from threading import Thread
+
+
+class WorkerThread(Thread):
+    def __init__(self, delay, target):
+        super().__init__()
+        self.delay = delay
+        self.target = target
+
+    def run(self):
+        # runs in custom thread, but can call Streamlit APIs
+        start_time = time.time()
+        time.sleep(self.delay)
+        end_time = time.time()
+        self.target.write(f"start: {start_time}, end: {end_time}")
+
+
+delays = [5, 4, 3, 2, 1]
+result_containers = []
+for i, delay in enumerate(delays):
+    st.header(f"Thread {i}")
+    result_containers.append(st.container())
+
+threads = [
+    WorkerThread(delay, container)
+    for delay, container in zip(delays, result_containers)
+]
+for thread in threads:
+    add_script_run_ctx(thread, get_script_run_ctx())
+    thread.start()
+
+for thread in threads:
+    thread.join()
+
+st.button("Rerun")

python/concept-source/multithreading-no-streamlit-batched.py

@@ -0,0 +1,29 @@
+import streamlit as st
+import time
+from threading import Thread
+
+
+class WorkerThread(Thread):
+    def __init__(self, delay):
+        super().__init__()
+        self.delay = delay
+        self.return_value = None
+
+    def run(self):
+        start_time = time.time()
+        time.sleep(self.delay)
+        end_time = time.time()
+        self.return_value = f"start: {start_time}, end: {end_time}"
+
+
+delays = [5, 4, 3, 2, 1]
+threads = [WorkerThread(delay) for delay in delays]
+for thread in threads:
+    thread.start()
+for thread in threads:
+    thread.join()
+for i, thread in enumerate(threads):
+    st.header(f"Thread {i}")
+    st.write(thread.return_value)
+
+st.button("Rerun")

python/concept-source/multithreading-no-streamlit-iterative.py

@@ -0,0 +1,40 @@
+import streamlit as st
+import time
+from threading import Thread
+
+
+class WorkerThread(Thread):
+    def __init__(self, delay):
+        super().__init__()
+        self.delay = delay
+        self.return_value = None
+
+    def run(self):
+        start_time = time.time()
+        time.sleep(self.delay)
+        end_time = time.time()
+        self.return_value = f"start: {start_time}, end: {end_time}"
+
+
+delays = [5, 4, 3, 2, 1]
+result_containers = []
+for i, delay in enumerate(delays):
+    st.header(f"Thread {i}")
+    result_containers.append(st.container())
+
+threads = [WorkerThread(delay) for delay in delays]
+for thread in threads:
+    thread.start()
+thread_lives = [True] * len(threads)
+
+while any(thread_lives):
+    for i, thread in enumerate(threads):
+        if thread_lives[i] and not thread.is_alive():
+            result_containers[i].write(thread.return_value)
+            thread_lives[i] = False
+    time.sleep(0.5)
+
+for thread in threads:
+    thread.join()
+
+st.button("Rerun")

python/concept-source/requirements.txt

@@ -0,0 +1 @@
+streamlit>=1.41.0