Concurrency control

Tune how many processing components can run at the same time with `max_inflight_components` or the `COCOINDEX_MAX_INFLIGHT_COMPONENTS` environment variable, and understand how CocoIndex avoids deadlocks in nested mount scenarios.

Version: v 1.0.0-alpha48

CocoIndex executes each processing component as a unit of concurrent work. By default, up to 1024 processing components can be in flight per app. When components perform resource-intensive work (e.g., calling external APIs, running ML models), you may want a tighter limit.

Setting the limit

Set max_inflight_components in AppConfig:

python

app = coco.App(
    coco.AppConfig(name="MyPipeline", max_inflight_components=4),
    app_main,
    sourcedir=pathlib.Path("./data"),
)

With max_inflight_components=4, at most 4 processing components execute at the same time. When a component finishes, the next pending one starts.

Setting max_inflight_components=1 serializes all components — only one runs at a time.

You can also set the limit via the COCOINDEX_MAX_INFLIGHT_COMPONENTS environment variable:

bash

export COCOINDEX_MAX_INFLIGHT_COMPONENTS=4

Precedence: AppConfig value > environment variable > default (1024).

Deadlock prevention

When a parent component mounts a child, the parent releases its concurrency slot so the child can make progress. This prevents deadlocks in nested mount scenarios — even with max_inflight_components=1, a parent mounting a child will not block forever.