final String key = "key";

    final AtomicLongMap<String> map = AtomicLongMap.create();

    ExecutorService threadPool = Executors.newFixedThreadPool(nThreads);
    ArrayList<Future<Long>> futures = new ArrayList<>();
    for (int i = 0; i < nTasks; i++) {
      futures.add(
          threadPool.submit(
              new Callable<Long>() {
                @Override
                public Long call() {

from starlette.concurrency import iterate_in_threadpool as iterate_in_threadpool  # noqa
from starlette.concurrency import run_in_threadpool as run_in_threadpool  # noqa
from starlette.concurrency import (  # noqa
    run_until_first_complete as run_until_first_complete,
)

_T = TypeVar("_T")


@asynccontextmanager
async def contextmanager_in_threadpool(
    cm: ContextManager[_T],
) -> AsyncGenerator[_T, None]:

    final String key = "key";

    final AtomicLongMap<String> map = AtomicLongMap.create();

    ExecutorService threadPool = Executors.newFixedThreadPool(nThreads);
    ArrayList<Future<Long>> futures = new ArrayList<>();
    for (int i = 0; i < nTasks; i++) {
      futures.add(
          threadPool.submit(
              new Callable<Long>() {
                @Override
                public Long call() {

        To be awaitable, compatible with async, this is run in threadpool.
        """
        return await super().seek(offset)

    async def close(self) -> None:
        """
        Close the file.

        To be awaitable, compatible with async, this is run in threadpool.
        """
        return await super().close()

    @classmethod