Ajax 请求偶尔会在 chrome 中停滞很长时间。
我终于设法复制了它并保存了所有必要的相关数据，如果有人能帮助我的话，我会在这里发布。
Chrome 开发工具的时间线显示请求停滞了 42.62 秒，如下面的屏幕截图所示:
在 chrome://net-internals/#events(对于事件日志，请转到末尾)页面中，我发现两个事件花费的时间最多:
- +HTTP_TRANSACTION_READ_HEADERS [dt=21301]
- +HTTP_TRANSACTION_READ_HEADERS [dt=21304]
都得到 ERR_CONNECTION_RESET。
我认为错误是请求停滞这么久的原因。
任何人都可以解释错误吗？
以下是请求的事件日志，我还将完整事件导出为 json，您可以从 here 获得然后在 Chrome chrome://net-internals/#events 页面中恢复。请注意请求 url 是内部的，因此可能无法从公共(public)网络访问:
193486: URL_REQUEST
http://qa.tieba.baidu.com/release/getReleaseHistory?projectId=fum1.0.593
Start Time: 2015-01-02 17:51:05.323
t= 1 [st= 0] +REQUEST_ALIVE [dt=42741]
t= 1 [st= 0] URL_REQUEST_DELEGATE [dt=0]
t= 1 [st= 0] +URL_REQUEST_START_JOB [dt=42740]
--> load_flags = 339804160 (BYPASS_DATA_REDUCTION_PROXY | MAYBE_USER_GESTURE | REPORT_RAW_HEADERS | VERIFY_EV_CERT)
--> method = "GET"
--> priority = "LOW"
--> url = "http://qa.tieba.baidu.com/release/getReleaseHistory?projectId=fum1.0.593"
t= 2 [st= 1] URL_REQUEST_DELEGATE [dt=0]
t= 2 [st= 1] HTTP_CACHE_GET_BACKEND [dt=0]
t= 2 [st= 1] HTTP_CACHE_OPEN_ENTRY [dt=0]
t= 2 [st= 1] HTTP_CACHE_ADD_TO_ENTRY [dt=0]
t= 2 [st= 1] HTTP_CACHE_READ_INFO [dt=0]
t= 2 [st= 1] URL_REQUEST_DELEGATE [dt=0]
t= 2 [st= 1] +HTTP_STREAM_REQUEST [dt=2]
t= 4 [st= 3] HTTP_STREAM_REQUEST_BOUND_TO_JOB
--> source_dependency = 193488 (HTTP_STREAM_JOB)
t= 4 [st= 3] -HTTP_STREAM_REQUEST
t= 4 [st= 3] +HTTP_TRANSACTION_SEND_REQUEST [dt=0]
t= 4 [st= 3] HTTP_TRANSACTION_SEND_REQUEST_HEADERS
--> GET /release/getReleaseHistory?projectId=fum1.0.593 HTTP/1.1
Host: qa.tieba.baidu.com
Connection: keep-alive
Accept: application/json, text/plain, */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36
Referer: http://qa.tieba.baidu.com/project/
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8
Cookie: [268 bytes were stripped]
t= 4 [st= 3] -HTTP_TRANSACTION_SEND_REQUEST
t= 4 [st= 3] +HTTP_TRANSACTION_READ_HEADERS [dt=21301]
t= 4 [st= 3] HTTP_STREAM_PARSER_READ_HEADERS [dt=21301]
--> net_error = -101 (ERR_CONNECTION_RESET)
t=21305 [st=21304] HTTP_TRANSACTION_RESTART_AFTER_ERROR
--> net_error = -101 (ERR_CONNECTION_RESET)
t=21305 [st=21304] -HTTP_TRANSACTION_READ_HEADERS
t=21305 [st=21304] +HTTP_STREAM_REQUEST [dt=3]
t=21307 [st=21306] HTTP_STREAM_REQUEST_BOUND_TO_JOB
--> source_dependency = 193494 (HTTP_STREAM_JOB)
t=21308 [st=21307] -HTTP_STREAM_REQUEST
t=21308 [st=21307] +HTTP_TRANSACTION_SEND_REQUEST [dt=3]
t=21308 [st=21307] HTTP_TRANSACTION_SEND_REQUEST_HEADERS
--> GET /release/getReleaseHistory?projectId=fum1.0.593 HTTP/1.1
Host: qa.tieba.baidu.com
Connection: keep-alive
Accept: application/json, text/plain, */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36
Referer: http://qa.tieba.baidu.com/project/
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8
Cookie: [268 bytes were stripped]
t=21311 [st=21310] -HTTP_TRANSACTION_SEND_REQUEST
t=21311 [st=21310] +HTTP_TRANSACTION_READ_HEADERS [dt=21304]
t=21311 [st=21310] HTTP_STREAM_PARSER_READ_HEADERS [dt=21304]
--> net_error = -101 (ERR_CONNECTION_RESET)
t=42615 [st=42614] HTTP_TRANSACTION_RESTART_AFTER_ERROR
--> net_error = -101 (ERR_CONNECTION_RESET)
t=42615 [st=42614] -HTTP_TRANSACTION_READ_HEADERS
t=42615 [st=42614] +HTTP_STREAM_REQUEST [dt=12]
t=42627 [st=42626] HTTP_STREAM_REQUEST_BOUND_TO_JOB
--> source_dependency = 193498 (HTTP_STREAM_JOB)
t=42627 [st=42626] -HTTP_STREAM_REQUEST
t=42627 [st=42626] +HTTP_TRANSACTION_SEND_REQUEST [dt=2]
t=42627 [st=42626] HTTP_TRANSACTION_SEND_REQUEST_HEADERS
--> GET /release/getReleaseHistory?projectId=fum1.0.593 HTTP/1.1
Host: qa.tieba.baidu.com
Connection: keep-alive
Accept: application/json, text/plain, */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36
Referer: http://qa.tieba.baidu.com/project/
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8
Cookie: [268 bytes were stripped]
t=42629 [st=42628] -HTTP_TRANSACTION_SEND_REQUEST
t=42629 [st=42628] +HTTP_TRANSACTION_READ_HEADERS [dt=112]
t=42629 [st=42628] HTTP_STREAM_PARSER_READ_HEADERS [dt=112]
t=42741 [st=42740] HTTP_TRANSACTION_READ_RESPONSE_HEADERS
--> HTTP/1.1 200 OK
Date: Fri, 02 Jan 2015 09:51:48 GMT
Content-Type: application/json; charset=UTF-8
Transfer-Encoding: chunked
Connection: keep-alive
Cache-Control: no-cache
tracecode: 31079600320335034634010217
tracecode: 31079600320537995786010217
Server: Apache
t=42741 [st=42740] -HTTP_TRANSACTION_READ_HEADERS
t=42741 [st=42740] HTTP_CACHE_WRITE_INFO [dt=0]
t=42741 [st=42740] HTTP_CACHE_WRITE_DATA [dt=0]
t=42741 [st=42740] HTTP_CACHE_WRITE_INFO [dt=0]
t=42741 [st=42740] URL_REQUEST_DELEGATE [dt=0]
t=42741 [st=42740] -URL_REQUEST_START_JOB
t=42741 [st=42740] URL_REQUEST_DELEGATE [dt=0]
t=42741 [st=42740] HTTP_TRANSACTION_READ_BODY [dt=0]
t=42741 [st=42740] HTTP_CACHE_WRITE_DATA [dt=0]
t=42741 [st=42740] HTTP_TRANSACTION_READ_BODY [dt=0]
t=42741 [st=42740] HTTP_CACHE_WRITE_DATA [dt=0]
t=42742 [st=42741] -REQUEST_ALIVE最佳答案
我曾经遇到过类似的问题。问题的原因是每个浏览器都限制了到服务器的最大 TCP 连接数。对于 chrome，限制为六个。当您使用代理服务器时，问题更加突出，因为所有请求都转到同一台服务器(代理服务器)。
Chrome 不允许您更改此限制。事实上不应该。如果你想知道更多关于为什么存在这个限制，以及其他浏览器的限制是什么，你可以阅读this article .
之所以这个限制很少成为问题，是因为对同一主机的多个 HTTP 请求大多是连续发送的，而不是并行发送的，最好是通过同一个 TCP 连接。
如果您经常遇到这个问题，那么原因可能是:
服务器不支持持久 TCP 连接:如果问题仅在访问特定服务器时出现，原因可能是 chrome 正在获取多个资源(如图像、CSS 文件、等)并行连接。由于在您的情况下，服务器位于您的本地网络上，因此您可能希望请求服务器管理员添加对持久 TCP 连接的支持。
打开了多个持久连接:如果您在代理服务器后面工作，那么同时下载多个文件或打开保持 TCP 连接打开的站点可能是您遇到问题的原因。要摆脱它，您所能做的就是不要同时下载很多东西(如果必须的话，也可以在不同的浏览器中下载)。
PS: 错误 net_error = -101 (ERR_CONNECTION_RESET) 不是由于 header 无效，而是因为超时，正在等待与服务器的先前连接关闭。
关于javascript - 请求在 chrome 中偶尔会停滞很长时间，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27740692/