Max parallel threads (#1460)
* Set max parallel threads to 100.
I could not find a better solution than monkey-patching
`anyio.to_thread.run_sync` to use a custom `CapacityLimiter`. I did try
to obtain the predictions inside a context handler instead:
```
async with self.limiter:
predictions = await run_in_threadpool(block_fn.fn, *processed_input)
```
However, that approach didn't seem to work.
* Make max parallel threads configurable.
`max_threads` can now be used in `launch` to specify the desired number
of parallel threads supported.
* Fix import order.
* Update gradio/blocks.py
* Replace `run_in_threadpool` with `run_sync`.
We create the capacity limiter on launch, and invoke
`anyio.to_thread.run_sync` directly instead of going through
`run_in_threadpool`. This allows for some code simplification: we no
longer need to patch `anyio.to_thread.run_sync`.
* max_parallel_threads
- resolve conflicts
* max_parallel_threads
- solve error
* max_parallel_threads
- solve async error
Co-authored-by: Pedro Cuenca <pedro@latenitesoft.com>
