大红包 请教一个 rust 延迟的问题，

1. 在片段一中执行 解析 json 只需要 2us ， 为何在 片段二中，加了行 sleep 代码后执行时间慢到 60us ？
2. 为何 websocket 库中 read message loop 中解析 json 也是慢到 20-60us?

rust 中 sleep 代码实现

#[cfg(not(target_os = "espidf"))] pub fn sleep(dur: Duration) { let mut secs = dur.as_secs(); let mut nsecs = dur.subsec_nanos() as _; // If we're awoken with a signal then the return value will be -1 and // nanosleep will fill in `ts` with the remaining time. unsafe { while secs > 0 || nsecs > 0 { let mut ts = libc::timespec { tv_sec: cmp::min(libc::time_t::MAX as u64, secs) as libc::time_t, tv_nsec: nsecs, }; secs -= ts.tv_sec as u64; let ts_ptr = &mut ts as *mut _; if libc::nanosleep(ts_ptr, ts_ptr) == -1 { assert_eq!(os::errno(), libc::EINTR); secs += ts.tv_sec as u64; nsecs = ts.tv_nsec; } else { nsecs = 0; } } } } 

use serde::{Serialize, Deserialize}; use std::time::Instant; use std::time; use tungstenite::{connect, Message}; use url::Url; #[derive(Serialize, Deserialize)] pub struct OkexWsArg { pub channel: String, #[serde(rename(deserialize = "instId"))] pub inst_id: String, } #[derive(Serialize, Deserialize)] pub struct OkexWsDepthItem { pub asks: [[String; 4]; 5], pub bids: [[String; 4]; 5], #[serde(rename(deserialize = "instId"))] pub inst_id: String, pub ts: String, } #[derive(Serialize, Deserialize)] pub struct OkexWsDepth { pub arg: OkexWsArg, pub data: [OkexWsDepthItem; 1], } fn main(){ // 片段一 for n in 0..10 { let start = Instant::now(); let raw_msg = r#"{"arg":{"channel":"books5","instId":"BTC-USDT-SWAP"},"data":[{"asks":[["42185.1","959","0","32"],["42186.4","132","0","2"],["42186.7","6","0","6"],["42186.9","59","0","2"],["42187.2","19","0","2"]],"bids":[["42185","285","0","6"],["42183.3","15","0","1"],["42181.8","3","0","1"],["42181.7","6","0","3"],["42181.6","46","0","18"]],"instId":"BTC-USDT-SWAP","ts":"1642613619147"}]}"#; match serde_json::from_str::<OkexWsDepth>(&raw_msg.to_string()) { Ok(msg) => { println!("parse: {}", msg.data.first().unwrap().ts); }, Err(err) => { println!("parse error {:?} {:?}", raw_msg, err); } } println!("1-{} time cost: {:?} us",n, start.elapsed().as_micros()); } // 片段二 for n in 0..10 { std::thread::sleep(time::Duration::from_millis(100)); let start = Instant::now(); let raw_msg = r#"{"arg":{"channel":"books5","instId":"BTC-USDT-SWAP"},"data":[{"asks":[["42185.1","959","0","32"],["42186.4","132","0","2"],["42186.7","6","0","6"],["42186.9","59","0","2"],["42187.2","19","0","2"]],"bids":[["42185","285","0","6"],["42183.3","15","0","1"],["42181.8","3","0","1"],["42181.7","6","0","3"],["42181.6","46","0","18"]],"instId":"BTC-USDT-SWAP","ts":"1642613619147"}]}"#; match serde_json::from_str::<OkexWsDepth>(&raw_msg.to_string()) { Ok(msg) => { println!("parse: {}", msg.data.first().unwrap().ts); }, Err(err) => { println!("parse error {:?} {:?}", raw_msg, err); } } println!("2-{} time cost: {:?} us",n, start.elapsed().as_micros()); } }