Creating an AioClient locks up in distributed 1.25.3

This short reproducer works in distributed 1.25.2, but locks up in 1.25.3. This behavior is triggered in https://github.com/LiberTEM/LiberTEM/ when creating a dask cluster and leads to a hard freeze of the application.

Update: The behavior is observed both on Windows 10 and on Linux.

import asyncio

from dask import distributed as dd
from distributed.asyncio import AioClient


async def async_main():
    cluster_kwargs = {
        "threads_per_worker": 1,
        "asynchronous": True,
        "n_workers": 2
    }
    client_kwargs = {}
    print("starting cluster...")
    cluster = dd.LocalCluster(**(cluster_kwargs or {}))
    print("cluster started.")
    print("creating client...")
    client = await AioClient(cluster, **(client_kwargs or {}))
    print("success")


if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(async_main())

Expected behavior: It continues working the same in all version past 1.25.2.

[mrocklin]

I’m curious, can you just use a normal Client? Tornado and Asyncio have merged to the point where I’m starting to suspect that AioClient may no longer be worth the maintenance effort.

On Wed, Feb 20, 2019 at 4:06 AM Dieter Weber [e-mail] wrote:

This short reproducer works in distributed 1.25.2, but locks up in 1.25.3. This behavior is triggered in https://github.com/LiberTEM/LiberTEM/ when creating a dask cluster and leads to a hard freeze of the application.

import asyncio from dask import distributed as ddfrom distributed.asyncio import AioClient

async def async_main(): cluster_kwargs = { “threads_per_worker”: 1, “asynchronous”: True, “n_workers”: 2 } client_kwargs = {} cluster = dd.LocalCluster(**(cluster_kwargs or {})) client = await AioClient(cluster, **(client_kwargs or {})) print(“success”)

if name == ‘main’: loop = asyncio.get_event_loop() loop.run_until_complete(async_main())

Expected behavior: It continues working the same in all version past 1.25.2.

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[kszucs]

Yeah, I suggest pinning tornado 5 and deprecating AioClient as a wrapper for Client(asynchronous=True).