For things that take a long process you can run them in a separate thread and in a function with independent rerun using fragment so that it will not affect things running in the main thread.
Here is an example, there are two functions simple_chart() and analysis(). You can run analysis on its own thread to do its work. While it is running, you can interact with the chart.
def main():
# Run in main thread.
simple_chart()
# Run in a separate thread.
analysis()
In this example, the analysis() is this:
@st.experimental_fragment
def analysis():
with st.container(border=True):
st.markdown('The process will be run from a different thread and reruns will be executed within the function only.')
num_jobs = st.number_input('Number of jobs', value=8, min_value=5, max_value=100, step=1)
st.button('start process', on_click=process_cb, disabled=ss.is_btn_disabled, type='primary')
if ss.is_btn_disabled:
wt = threading.Thread(target=work_process, args=(num_jobs,), daemon=True)
add_script_run_ctx(wt)
wt.start()
wt.join()
# Rerun to redraw the button as enabled.
st.rerun()
The work_process function is run in a different thread.
def work_process(njobs):
done = 0
while done < njobs:
time.sleep(2)
done += 1
ss.is_btn_disabled = False # enable button
The process button is disabled after starting it and restored once done.
Complete code
import streamlit as st
from streamlit import session_state as ss
import numpy as np
import threading
from streamlit.runtime.scriptrunner import add_script_run_ctx
import time
if 'is_btn_disabled' not in ss:
ss.is_btn_disabled = False
def simple_chart():
color_dict = {
'midnightblue': 'rgb(25, 25, 112)',
'indigo': 'rgb(75, 0, 130)',
'red': 'rgb(255, 0, 0)',
'slategray': 'rgb(112, 128, 144)'
}
with st.container(border=True):
st.markdown('This will be run from the main thread.')
selected_color = st.selectbox('Bar Color', options=list(color_dict.keys()))
val = st.slider("Number of bars", 1, 20, 4)
st.bar_chart(np.random.default_rng().random(val), height=200, color=color_dict[selected_color])
def process_cb():
ss.is_btn_disabled = True # disable button
def work_process(njobs):
done = 0
while done < njobs:
time.sleep(2)
done += 1
ss.is_btn_disabled = False # enable button
@st.experimental_fragment
def analysis():
with st.container(border=True):
st.markdown('The process will be run from a different thread and reruns will be executed within the function only.')
num_jobs = st.number_input('Number of jobs', value=8, min_value=5, max_value=100, step=1)
st.button('start process', on_click=process_cb, disabled=ss.is_btn_disabled, type='primary')
if ss.is_btn_disabled:
wt = threading.Thread(target=work_process, args=(num_jobs,), daemon=True)
add_script_run_ctx(wt)
wt.start()
wt.join()
# Rerun to redraw the button as enabled.
st.rerun()
def main():
# Run in main thread.
simple_chart()
# Run in a separate thread.
analysis()
if __name__ == '__main__':
main()
You need to use streamlit 1.33
