AJAX请求挂起5分钟 [英] AJAX request hangs for 5 minutes

问题描述

我的网站对PHP文件使用大量AJAX请求，然后从MySQL检索

数据。大约95％的时间请求完成而没有

问题。每隔一段时间，一个请求就会挂起5分钟，然后就会失败。它似乎在客户端出现。我不能
重新创建问题。它只是随机发生的。我认为它最终会到达服务器（Apache），因为我可以在

服务器日志中看到某些POST / GET变量未定义的错误。

变量已明确定义。有一件事可能是因为我在某处看到POST向服务器发出两个

请求，因此它只与POST请求相关联。我有IE6和IE7的这个问题，可以将

绑定到我简要阅读的wininet.dll。我不确定。以下是我用于请求的典型结构。任何帮助

将不胜感激。谢谢...


函数loginReq（frm）{

var req = false;

var msg = document.getElementById（ " msg"）;

msg.innerHTML ="" ;;

msg.className =" error";

if（ window.XMLHttpRequest）{

req = new XMLHttpRequest（）;

} else if（window.ActiveXObject）{

try {req = new ActiveXObject（" Msxml2.XMLHTTP"）;} catch（e）{

try {req = new ActiveXObject（" Microsoft.XMLHTTP"）;} catch（e）{}}
}

if（！req）{

msg.innerHTML ="请求有问题！" ;;

返回false;

}

req.onreadystatechange = function（）{

if（req.readyState == 4）{

if（req.status == 200）{

if（req.responseText.substr（0,1）==''<''）{

document.getElementById（" main"）。innerHTML = req.resp onseText;

} else {

msg.innerHTML = req.responseText;

}

}否则{

msg.innerHTML ="请求有问题！" ;;

}

}

}

var prm =''user =''+ frm.user.value +''& passwd =''+ frm.passwd.v alue;

req.open（' 'POST''，''login.php''，true）;

req.setRequestHeader（" Content-type"，" application / x-www-form-

urlencoded"）;

req.setRequestHeader（" Content-length"，prm.length）;

req.setRequestHeader（" Connection"，"关闭）;

req.send（prm）;

}

解决方案

< a href =mailto：mo ***** @ yahoo.com> mo ***** @ yahoo.com 写道：

我的网站对PHP文件使用了大量的AJAX请求，然后从MySQL检索了

数据。大约95％的时间请求完成而没有

问题。每隔一段时间，一个请求就会挂起5分钟，然后就会失败。它似乎在客户端出现。我不能
重新创建问题。它只是随机发生的。

读取就像竞争条件。

我认为它最终到达服务器（Apache）因为我可以在服务器日志中看到错误

，某些POST / GET变量未定义。

变量已明确定义。有一件事可能是因为我在某处看到POST向服务器发出两个

请求，因此它只与POST请求相关联。

你要么完全没读或完全误解了你的b
。一个（POST）请求仍然是* one *（POST）请求。

我在IE6和IE7上遇到此问题，可能与wininet.dll绑定/>
我也简要介绍了一下。我不确定。

在Windows上运行的其他UA也不得不使用wininet.dll吗？


< http： //msdn.microsoft.com/en-us/library/aa385483.aspx>

以下是我用于请求的典型结构。任何帮助将

表示赞赏。谢谢...


函数loginReq（frm）{

[...]

if（window.XMLHttpRequest）{

^^^^^^^^^^^^^^^^^^^^^

req = new XMLHttpRequest（）;

} else if（window.ActiveXObject）{

^^^^^^^^ ^^^^^^^^^^^^^

这些功能测试都不够。例如，并非每个属性都可以调用
。而且你不应该依赖于`window''属性来引用全局对象的
。阅读常见问题解答并在两者上搜索档案。

try {req = new ActiveXObject（" Msxml2.XMLHTTP"）;} catch（e）{

try {req = new ActiveXObject（" Microsoft.XMLHTTP"）;} catch（e）{}}

}

测试Microsoft.XMLHTTP通常就足够了。

if（！req）{

msg.innerHTML ="请求有问题！;

返回false;

}

req.onreadystatechange = function（）{

[...]

}

var prm =''user =''+ frm.user.value +''& passwd ='' + frm.passwd.v alue;

如果你声明`Content-type：application / x-www-form-urlencoded''，你必须要求
转义那些值您使用RFC3986中定义的百分比编码作为URI组件或在邮件正文中使用
。实现

ECMAScript Ed。 3为此提供了encodeURIComponent（）方法;对于较旧的实现，你需要使用escape（）
甚至可能是一个虚拟方法，因为

后备。

req.open（''POST''，''login.php''，true）;

该调用必须在*指定给'onreadystatechange''属性之前*

req .setRequestHeader（" Content-type"，" application / x-www-form-

urlencoded"）;

此调用不是普遍支持的，您需要对其进行功能测试，并且

捕获它可能抛出的异常。无论如何，它可能是多余的。

req.setRequestHeader（" Content-length"，prm.length）;

req。 setRequestHeader（QUOT;连接与QUOT;，"靠近"）;

这些调用毫无意义，实现可能会忽略它们。

req.send（prm） ;

}

HTH


PointedEars

-

var bugRiddenCrashPronePieceOfJunk =（

navigator.userAgent.indexOf（''MSIE 5''）！= -1

&& navigator .userAgent.indexOf（''Mac''）！= -1

）// Plone，register_function.js：16

function loginReq （frm）{

[...]

* if（window.XMLHttpRequest）{

* * * * ^^^^^^^^^^^^^^^^^^^^^ * * req = new XMLHttpRequest（）;

*}否则if（window.ActiveXObject）{

* * * * * * * ^ ^^^^^^^^^^^^^^^^^^^

这些功能测试都不够。 *例如，并非每个属性都可以调用
。 *你不应该依赖'window''属性来引用全局对象
。 *阅读常见问题解答并在两者上搜索档案。

如果您指的是< http://www.jibbering.com/faq/ > ;,我不能'$

找到任何告诉我们不要依赖''window''属性的东西

指的是Global Object。如果我错了，请纠正我，但如果对于全局XMLHttpRequest属性的测试成功，我们几乎可以确保它是一个函数。

总是确定它是一个函数。

* req.open（''POST''，''login.php''，true）;

该调用必须在*指定给'onreadystatechange''属性之前*。

XMLHttpRequest的工作草案说它是在你分配

onreadystatechange属性之后发生的。

< http://www.w3.org/TR/XMLHttpRequest/ > ;

* req.setRequestHeader（" Content-type"，" application / x-www-form-

urlencoded"）;

此调用不受普遍支持，您需要对其进行功能测试，并且

捕获它可能抛出的异常。 *无论如何，它可能是多余的。

虽然XMLHttpRequest仍然没有标准化，但是每个实现并不是每个实现提供一个setRequestHeader函数吗？

>

* req.setRequestHeader（" Content-length"，prm.length）;

* req.setRequestHeader（" Connection" ，"靠近"）;

这些调用毫无意义，实现可能会忽略它们。

当

发出HTTP请求时，浏览器使用的默认连接请求标头是保持活动，所以如果XHR实现/

HTTP客户端选择忽略覆盖默认值的那个，

不会有点错吗？

9月14日下午2：15 *，Thomas''PointedEars''Lahn< PointedE ... @ web.de>

写道：

sasuke写道：

当
$时，浏览器使用的默认连接请求标头b $ b发出HTTP请求是''Keep-Alive''

废话。 *显然你不知道你在说什么。 *阅读

RFC 1945和2616，请不要在此之前继续。

我想不是每个浏览器都在那里，但至少FF工作

这样。使用嗅探工具捕获Request标头在

最少说。但你是对的，这不是授权。

所以如果XHR实现/ HTTP客户端选择忽略

一个覆盖默认值，不会有点错吗？

非sequitur。 *为什么不简单地测试我的建议？ * BTDT。


有人想知道为什么你在这里问你是否认为你知道的更好。

请从我之前的帖子中指出一个段落，表明我的

声称知道一切。我知道你比我更清楚因此

这些问题不是''问号''而是真正的''查询''。

向每个人劫持线程表示歉意;很好奇。不过，

无论如何，谢谢你的澄清。


问候，

/ sasuke。

My site uses lots of AJAX requests to PHP files which then retrieves
data from MySQL. About 95% of the time the requests complete without
issues. Every once in a while a request will hang for exactly 5
minutes then fail. It seems to be occuring on the client side. I
can''t re-create the issue. It just happens randomly. I think it
eventally reaches the server (Apache) because I can see errors in the
server log that certain POST/GET variables are undefined. The
variables are clearly defined. One thing it could be is that it''s
only tied to POST requests since I read somewhere that POST makes two
requests to the server. I have this issue with IE6 and IE7 and could
be tied to the wininet.dll I briefly read about as well. I''m not
sure. Below is the typical structure I use for my requests. Any help
will be appreciated. Thanks...

function loginReq(frm){
var req=false;
var msg=document.getElementById("msg");
msg.innerHTML="";
msg.className="error";
if(window.XMLHttpRequest){
req=new XMLHttpRequest();
}else if(window.ActiveXObject){
try{req=new ActiveXObject("Msxml2.XMLHTTP");}catch(e){
try{req=new ActiveXObject("Microsoft.XMLHTTP");}catch(e){}}
}
if(!req){
msg.innerHTML="There was a problem with the request!";
return false;
}
req.onreadystatechange=function(){
if(req.readyState==4){
if(req.status==200){
if(req.responseText.substr(0,1)==''<''){
document.getElementById("main").innerHTML=req.resp onseText;
}else{
msg.innerHTML=req.responseText;
}
}else{
msg.innerHTML="There was a problem with the request!";
}
}
}
var prm=''user=''+frm.user.value+''&passwd=''+frm.passwd.v alue;
req.open(''POST'',''login.php'',true);
req.setRequestHeader("Content-type","application/x-www-form-
urlencoded");
req.setRequestHeader("Content-length",prm.length);
req.setRequestHeader("Connection","close");
req.send(prm);
}

解决方案

mo*****@yahoo.com wrote:

My site uses lots of AJAX requests to PHP files which then retrieves
data from MySQL. About 95% of the time the requests complete without
issues. Every once in a while a request will hang for exactly 5
minutes then fail. It seems to be occuring on the client side. I
can''t re-create the issue. It just happens randomly.

Reads like a race condition.

I think it eventally reaches the server (Apache) because I can see errors
in the server log that certain POST/GET variables are undefined. The
variables are clearly defined. One thing it could be is that it''s
only tied to POST requests since I read somewhere that POST makes two
requests to the server.

Either you have read utter nonsense or misunderstood completely what you had
read. One (POST) request is still *one* (POST) request.

I have this issue with IE6 and IE7 and could be tied to the wininet.dll
I briefly read about as well. I''m not sure.

Wouldn''t other UAs running on Windows have to use wininet.dll as well?

<http://msdn.microsoft.com/en-us/library/aa385483.aspx>

Below is the typical structure I use for my requests. Any help will
be appreciated. Thanks...

function loginReq(frm){
[...]
if(window.XMLHttpRequest){

^^^^^^^^^^^^^^^^^^^^^

req=new XMLHttpRequest();
}else if(window.ActiveXObject){

^^^^^^^^^^^^^^^^^^^^
Those are hardly sufficient feature tests. For example, not every property
can be called. And you should not rely on the `window'' property to refer to
the Global Object. Read the FAQ and search the archives on both.

try{req=new ActiveXObject("Msxml2.XMLHTTP");}catch(e){
try{req=new ActiveXObject("Microsoft.XMLHTTP");}catch(e){}}
}

Testing for `Microsoft.XMLHTTP'' usually suffices.

if(!req){
msg.innerHTML="There was a problem with the request!";
return false;
}
req.onreadystatechange=function(){
[...]
}
var prm=''user=''+frm.user.value+''&passwd=''+frm.passwd.v alue;

If you declare `Content-type: application/x-www-form-urlencoded'', you MUST
escape the values that you use as an URI component or in the message body,
using the percent encoding defined in RFC3986. Implementations of
ECMAScript Ed. 3 provide the encodeURIComponent() method for that purpose;
for older implementations you need escape() and maybe even a dummy method as
fallbacks.

req.open(''POST'',''login.php'',true);

That call must come *before* you assign to the `onreadystatechange'' property.

req.setRequestHeader("Content-type","application/x-www-form-
urlencoded");

This call is not universally supported, you need to feature-test it and
catch the exceptions it may throw. It is likely to be superfluous anyway.

req.setRequestHeader("Content-length",prm.length);
req.setRequestHeader("Connection","close");

These calls are pointless, the implementation will likely ignore them.

req.send(prm);
}

HTH

PointedEars
--
var bugRiddenCrashPronePieceOfJunk = (
navigator.userAgent.indexOf(''MSIE 5'') != -1
&& navigator.userAgent.indexOf(''Mac'') != -1
) // Plone, register_function.js:16

function loginReq(frm){

[...]
* if(window.XMLHttpRequest){

* * * *^^^^^^^^^^^^^^^^^^^^^* * req=new XMLHttpRequest();

* }else if(window.ActiveXObject){

* * * * * * *^^^^^^^^^^^^^^^^^^^^
Those are hardly sufficient feature tests. *For example, not every property
can be called. *And you should not rely on the `window'' property to refer to
the Global Object. *Read the FAQ and search the archives on both.

If you are referring to < http://www.jibbering.com/faq/ >, I couldn''t
find anything which tells us not to rely on the ''window'' property to
refer to Global Object. Correct me if I am wrong but if the test for
the Global XMLHttpRequest property is successful, we can be almost
always sure that it will be a function.

* req.open(''POST'',''login.php'',true);

That call must come *before* you assign to the `onreadystatechange'' property.

The working draft of XMLHttpRequest says it comes after you assign the
onreadystatechange property.
< http://www.w3.org/TR/XMLHttpRequest/ >

* req.setRequestHeader("Content-type","application/x-www-form-
urlencoded");

This call is not universally supported, you need to feature-test it and
catch the exceptions it may throw. *It is likely to be superfluous anyway.

Though XMLHttpRequest is still not standardized, doesn''t each and
every implementation out there provide a setRequestHeader function?

>

* req.setRequestHeader("Content-length",prm.length);
* req.setRequestHeader("Connection","close");

These calls are pointless, the implementation will likely ignore them.

The default ''Connection'' request header used by the browser when
issuing HTTP Requests is ''Keep-Alive'' so if the XHR implementation /
HTTP Client chooses to ignore the one which overrides the default,
wouldn''t it be kind of wrong?

On Sep 14, 2:15*pm, Thomas ''PointedEars'' Lahn <[e-mail]>
wrote:

sasuke wrote:

The default ''Connection'' request header used by the browser when
issuing HTTP Requests is ''Keep-Alive''

Nonsense. *Obviously you have no idea what you are talking about. *Read
RFCs 1945 and 2616, and please don''t continue here before you did.

I guess not on each and every browser out there but at least FF works
this way. Trapping the Request headers with a sniffing tool says so at
least. But you are right, it''s not a mandate.

so if the XHR implementation / HTTP Client chooses to ignore the
one which overrides the default, wouldn''t it be kind of wrong?

Non sequitur. *Why don''t you simply test my advice? *BTDT.

One wonders why you asked here if you think you know everything better.

Kindly point me a passage from my previous post which indicates my
claiming to know everything. I know you know better than me hence
those questions were not ''question tags'' but genuine ''queries''.
Apologies to everyone for hijacking the thread; was curious. Still,
anyways, thanks for the clarifications.

Regards,
/sasuke.

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