TrioExecutor acquires the capacity limiter too many times.

[1ekf]

TrioExecutor shares the limiter with the underlying trio.to_thread.run_sync call, so more tokens are consumed than are intended.

Reproducible example:

import asyncio
import trio_asyncio

async def amain():
    loop = asyncio.get_event_loop()
    executor = trio_asyncio.TrioExecutor(max_workers=1)
    await loop.run_in_executor(executor, print, "hello")

trio_asyncio.run(trio_asyncio.aio_as_trio(amain))

This call will always block, as TrioExecutor acquires the only token available and the inner trio.to_thread.run_sync cannot acquire its own token.

[1ekf]

Since trio.to_thread.run_sync always acquires a token before spawning a thread, it seems sufficient to remove capacity limiter acquire/release in the TrioExecutor.submit implementation.