import { EventEmitter } from 'node:events';
interface WorkerMsgBody<T> {
    type: string;
    data: T;
    [key: string]: unknown;
}
type Callback<R, T> = (err: Error | null, result: WorkerMsgBody<R> | null, task: T, startTime: number) => void;
/**
 * create worker pools
 * @example
 * ```ts
 * import { WorkerPool } from '@lzwme/fe-utils';
 * import { isMainThread, parentPort } from 'node:worker_threads';
 * import { statSync } from 'node:fs';
 * import { resolve } from 'node:path';
 *
 * if (isMainThread) {
 *   const wp = new WorkerPool<string, number>(path.resolve('wp-test.js'), cpus().length);
 *   wp.runTask('/a.txt', (size) => console.log(size)); // run more tasks...
 * } else {
 *   parentPort.on('message', (filepath: string) => {
 *     parentPort.postMessage(statSync(filepath).size);
 *   });
 * }
 * ```
 */
export declare class WorkerPool<T = unknown, R = unknown> extends EventEmitter {
    private processorFile;
    numThreads: number;
    private workers;
    private freeWorkers;
    private workerTaskInfo;
    private tasks;
    constructor(processorFile: string, numThreads?: number);
    private addNewWorker;
    runTask(task: T, callback: Callback<R, T>): void;
    removeTask(task: T | ((task: T) => boolean)): number;
    status(): {
        file: string;
        numThreads: number;
        tasksSize: number;
        freeize: number;
    };
    close(): void;
}
export {};