Concurrency¶

Async kernel runs message request with one of the following RunModes.

• blocking: Run the handler directly blocking the message loop
• queue: Run in a queue
• task: Run in a task
• thread: Run in a Caller thread

The kernel decides the run mode dynamically with the method [get_run_mode][async_kernel.kernel.Kernel.get_run_mode].

In [1]:

from async_kernel import utils
from async_kernel.typing import KernelConcurrencyMode, MsgType, RunMode

kernel = utils.get_kernel()

kernel.get_run_mode(MsgType.comm_msg)

from async_kernel import utils from async_kernel.typing import KernelConcurrencyMode, MsgType, RunMode kernel = utils.get_kernel() kernel.get_run_mode(MsgType.comm_msg)

<RunMode.task: 'task'>

The kernel.concurrency_mode will also change the RunMode that is returned by kernel.get_run_mode.

In [2]:

kernel.concurrency_mode = KernelConcurrencyMode.blocking
print(f"""
kernel.concurrency_mode: {kernel.concurrency_mode!s}    
kernel.get_run_mode:     {kernel.get_run_mode(MsgType.comm_msg).name}""")

kernel.concurrency_mode = KernelConcurrencyMode.default
print(f"""
kernel.concurrency_mode: {kernel.concurrency_mode!s}    
kernel.get_run_mode:     {kernel.get_run_mode(MsgType.comm_msg).name}""")

kernel.concurrency_mode = KernelConcurrencyMode.blocking print(f""" kernel.concurrency_mode: {kernel.concurrency_mode!s} kernel.get_run_mode: {kernel.get_run_mode(MsgType.comm_msg).name}""") kernel.concurrency_mode = KernelConcurrencyMode.default print(f""" kernel.concurrency_mode: {kernel.concurrency_mode!s} kernel.get_run_mode: {kernel.get_run_mode(MsgType.comm_msg).name}""")

kernel.concurrency_mode: blocking    
kernel.get_run_mode:     blocking

kernel.concurrency_mode: default    
kernel.get_run_mode:     task

Below is a list of the run modes for the currently available concurrency modes.

Note

`blocking` mode is roughly equivalent to how IpyKernel < 7.0 operates.

In [3]:

data = kernel.all_concurrency_run_modes()
try:
    import pandas as pd
except ImportError:
    print(data)
else:
    data = pd.DataFrame(data)
    data["RunMode"] = data.RunMode.str.replace("##", "")
    data = data.pivot(index="MsgType", columns=["KernelConcurrencyMode", "SocketID"], values="RunMode")  # noqa: PD010
    display(data)

data = kernel.all_concurrency_run_modes() try: import pandas as pd except ImportError: print(data) else: data = pd.DataFrame(data) data["RunMode"] = data.RunMode.str.replace("##", "") data = data.pivot(index="MsgType", columns=["KernelConcurrencyMode", "SocketID"], values="RunMode") # noqa: PD010 display(data)

KernelConcurrencyMode	default	blocking	default	blocking
SocketID	shell	shell	control	control
MsgType
comm_close	blocking	blocking	blocking	blocking
comm_info_request	blocking	blocking	blocking	blocking
comm_msg	task	blocking	task	blocking
comm_open	blocking	blocking	blocking	blocking
complete_request	thread	blocking	thread	blocking
debug_request	None	blocking	task	blocking
execute_request	queue	blocking	task	blocking
history_request	thread	blocking	thread	blocking
inspect_request	thread	blocking	thread	blocking
interrupt_request	task	blocking	task	blocking
is_complete_request	thread	blocking	thread	blocking
kernel_info_request	blocking	blocking	blocking	blocking
shutdown_request	None	blocking	task	blocking

Execute request run mode¶

There are a few options to modify how code cells are run.

• Metadata
• Directly in code
• tags
• Message header (in custom messages)

Warning

Only Jupyter lab is known to allow concurrent execution of cells.

Code for example¶

• This example requires ipywidgets
• Ensure you are running an async kernel

Lets define a function that we'll reuse for the remainder of the notebook.

In [4]:

async def demo():
    import threading

    import anyio
    from ipywidgets import Button

    from async_kernel import Caller, utils

    print("Run mode:", utils.get_job()["run_mode"])

    print(f"Thread name: '{threading.current_thread().name}'")
    button = Button(description="Finish")
    event = anyio.Event()
    caller = Caller()  # Use caller so the `##thread` example works.
    # This is because widget messages are received by the shell in the main thread. The event is being waited in this thread.
    button.on_click(lambda _: caller.call_direct(event.set))
    display(button)
    await event.wait()
    button.close()
    print(f"Finished ... thread name: '{threading.current_thread().name}'")
    return "Finished"

async def demo(): import threading import anyio from ipywidgets import Button from async_kernel import Caller, utils print("Run mode:", utils.get_job()["run_mode"]) print(f"Thread name: '{threading.current_thread().name}'") button = Button(description="Finish") event = anyio.Event() caller = Caller() # Use caller so the `##thread` example works. # This is because widget messages are received by the shell in the main thread. The event is being waited in this thread. button.on_click(lambda _: caller.call_direct(event.set)) display(button) await event.wait() button.close() print(f"Finished ... thread name: '{threading.current_thread().name}'") return "Finished"

Lets run it normally (queue)

In [5]:

suppress-error

await demo()

await demo()

Run mode:

##queue

Thread name: 'MainThread'

Button(description='Finish', style=ButtonStyle())

In [6]:

suppress-error

##queue
# Tip: try running this cell while the previous cell is still busy.
await demo()

##queue # Tip: try running this cell while the previous cell is still busy. await demo()

Run mode:

##queue

Thread name: 'MainThread'

Button(description='Finish', style=ButtonStyle())

Run mode: task¶

The task mode instructs the kernel to execute the code in a task separate to the queue, Both task and thread execute modes can be started when the kernel is busy executing. There is no imposed limitation on the number of tasks (or threads) that can be run concurrently.

See also the Caller example on how to call directly.

In [7]:

suppress-error

RunMode.task  # noqa: B018  # Using the literal `RunMode` values directly is also possible. Though it may show up as a [Flake8 B018 issue](https://docs.astral.sh/ruff/rules/useless-expression/)
await demo()

RunMode.task # noqa: B018 # Using the literal `RunMode` values directly is also possible. Though it may show up as a [Flake8 B018 issue](https://docs.astral.sh/ruff/rules/useless-expression/) await demo()

Run mode:

##queue

Thread name: 'MainThread'

Button(description='Finish', style=ButtonStyle())

Run mode: thread¶

In [8]:

thread

suppress-error

# This time we'll use the tag to run the cell in a Thread
await demo()

# This time we'll use the tag to run the cell in a Thread await demo()

Run mode:

##queue

Thread name: 'MainThread'

Button(description='Finish', style=ButtonStyle())

In [9]:

##thread
%callers # magic provided by async kernel

##thread %callers # magic provided by async kernel

Running	Protected			Name

──────────────────────────────────────────────────────────────────────

   ✓	   🔐		MainThread	

   ✓	   🔐		ControlThread	

   ✓			Thread-3 (anyio_run_caller)	

   ✓			Thread-4 (anyio_run_caller)	← current thread