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usleep

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Wait for a certain length of time before an async function does any more work

namespace HH\Asio;

function usleep(
  int $usecs,
): Awaitable<void>;

This is similar to calling the PHP builtin usleep funciton, but is in the context of async, meaning that other Awaitables in the async scheduler can run while the async function that called usleep() waits until the length of time before asking to resume again.

Parameters​

  • int $usecs - The amount of time to wait, in microseconds.

Returns​