You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: heavy_tests.rs
    path of file: ./repos/sdk-core/tests
    
    the code of the file until where you have to start completion: use futures::{future::join_all, sink, stream::FuturesUnordered, StreamExt};
use std::time::{Duration, Instant};
use temporal_client::{WfClientExt, WorkflowClientTrait, WorkflowOptions};
use temporal_sdk::{ActContext, ActivityOptions, WfContext, WorkflowResult};
use temporal_sdk_core_protos::coresdk::{
    workflow_commands::ActivityCancellationType, AsJsonPayloadExt,
};
use temporal_sdk_core_test_utils::{workflows::la_problem_workflow, CoreWfStarter};

mod fuzzy_workflow;

#[tokio::test]
async fn activity_load() {
    const CONCURRENCY: usize = 512;

    let mut starter = CoreWfStarter::new("activity_load");
    starter
        .max_wft(CONCURRENCY)
        .max_cached_workflows(CONCURRENCY)
        .max_at_polls(10)
        .max_at(CONCURRENCY);
    let mut worker = starter.worker().await;

    let activity_id = "act-1";
    let activity_timeout = Duration::from_secs(8);
    let task_queue = starter.get_task_queue().to_owned();

    let wf_fn = move |ctx: WfContext| {
        let task_queue = task_queue.clone();
        let payload = "yo".as_json_payload().unwrap();
        async move {
            let activity = ActivityOptions {
                activity_id: Some(activity_id.to_string()),
                activity_type: "test_activity".to_string(),
                input: payload.clone(),
                task_queue,
                schedule_to_start_timeout: Some(activity_timeout),
                start_to_close_timeout: Some(activity_timeout),
                schedule_to_close_timeout: Some(activity_timeout),
                heartbeat_timeout: Some(activity_timeout),
                cancellation_type: ActivityCancellationType::TryCancel,
                ..Default::default()
            };
            let res = ctx.activity(activity).await.unwrap_ok_payload();
            assert_eq!(res.data, payload.data);
            Ok(().into())
        }
    };

    let starting = Instant::now();
    let wf_type = "activity_load";
    worker.register_wf(wf_type.to_o
    
async fn activity_load() {
    const CONCURRENCY: usize = 512;

    let mut starter = CoreWfStarter::new("activity_load");
    starter
        .max_wft(CONCURRENCY)
        .max_cached_workflows(CONCURRENCY)
        .max_at_polls(10)
        .max_at(CONCURRENCY);
    let mut worker = starter.worker().await;

    let activity_id = "act-1";
    let activity_timeout = Duration::from_secs(8);
    let task_queue = starter.get_task_queue().to_owned();

    let wf_fn = move |ctx: WfContext| {
        let task_queue = task_queue.clone();
        let payload = "yo".as_json_payload().unwrap();
        async move {
            let activity = ActivityOptions {
                activity_id: Some(activity_id.to_string()),
                activity_type: "test_activity".to_string(),
                input: payload.clone(),
                task_queue,
                schedule_to_start_timeout: Some(activity_timeout),
                start_to_close_timeout: Some(activity_timeout),
                schedule_to_close_timeout: Some(activity_timeout),
                heartbeat_timeout: Some(activity_timeout),
                cancellation_type: ActivityCancellationType::TryCancel,
                ..Default::default()
            };
            let res = ctx.activity(activity).await.unwrap_ok_payload();
            assert_eq!(res.data, payload.data);
            Ok(().into())
        }
    };

    let starting = Instant::now();
    let wf_type = "activity_load";
    worker.register_wf(wf_type.to_owned(), wf_fn);
    worker.register_activity(
        "test_activity",
        |_ctx: ActContext, echo: String| async move { Ok(echo) },
    );
    join_all((0..CONCURRENCY).map(|i| {
        let worker = &worker;
        let wf_id = format!("activity_load_{i}");
        async move {
            worker
                .submit_wf(
                    wf_id,
                    wf_type.to_owned(),
                    vec![],
                    WorkflowOptions::default(),
                )
                .await
                .unwrap();
        }
    }))
    .await;
    dbg!(starting.elapsed());

    let running = Instant::now();

    worker.run_until_done().await.unwrap();
    dbg!(running.elapsed());
}