export declare class ConcurrencyLimiter {
    private running;
    private queue;
    private readonly maxConcurrency;
    private activeSet;
    constructor(maxConcurrency: number);
    acquire(): Promise<void>;
    release(): void;
    track<T>(promise: Promise<T>): Promise<T>;
    drain(): Promise<void>;
    get activeCount(): number;
    get pendingCount(): number;
}