entityMap|0|type|LINK|mutability|MUTABLE|data|url|http://blogs.msdn.com/b/jasonz/archive/2004/05/31/145105.aspx|1|http://msdn.microsoft.com/en-us/library/t990ks23%2528v=vs.80%2529.aspx|2|http://msdn.microsoft.com/en-us/library/ms366723%2528v=vs.100%2529.aspx|3|http://msdn.microsoft.com/en-us/library/aa479328.aspx|4|http://msdn.microsoft.com/en-us/library/ms178586%2528v=vs.100%2529.aspx|5|http://msdn.microsoft.com/en-us/library/ms178581%2528v=vs.100%2529.aspx|6|http://msdn.microsoft.com/en-us/library/ms178594%2528v=vs.100%2529.aspx|blocks|key|242997|text|静态变量在应用程序域的生命周期中持续存在。因此，导致静态变量“重置”的两件事是应用程序域重启或使用新类。在使用存储在aspx+Page类中的静态变量的情况下，当ASP.NET决定将aspx+Page重新编译为新类，并用新的页面类替换旧的页面类时，您可能会丢失静态变量。|unstyled|depth|inlineStyleRanges|entityRanges|242998|由于这些原因，如果系统决定重新启动或替换类(.NET+doesn't+kill+or+unload+classes/assemblies+in+a+running+app+domain)，那么您的静态变量将重置，因为您将通过重新启动或替换获得一个新类。这既适用于aspx页面也适用于classes+in+the+App_Code+folder。|offset|length|242999|如果出于任何原因认为需要重新编译一个类(see+ASP.NET+dynamic+compilation)，ASP.NET将替换它。|243000|您无法防止应用程序域重启造成的静态变量丢失，但您可以尝试通过类替换来避免这种情况。您可以将静态变量放在一个不是aspx页面且不在App_Code目录中的类中。您可能希望将它们放在程序中的某个static+class上。|style|CODE|243001|public+static+class+GlobalVariables
{
++++public+static+int+SomeGlobalUnsecureID;
++++public++static+string+SomeGlobalUnsecureString;
}|code-block|syntax|javascript|243002|静态变量是每个池，这意味着如果你有两个池运行你的asp.net站点，你就有两个不同的静态变量。(Web+garden+mode)|243003|如果系统以这种方式重新启动asp.net应用程序，静态变量就会丢失。|243004|池决定需要重新编译。|ordered-list-item|fqfm4|你打开+app_offline.htm+文件|ctvtb|您手动重新启动池|4n0p0|池达到您定义的一些限制并重新启动。|cmod8|出于任何原因，您重新启动+iis+或池。|243010|这些静态变量不是线程安全的，特别是当你从不同的线程访问它们时，你需要使用lock关键字。|BOLD|243011|由于应用程序重启无论如何都会重置统计，如果您真的想要持久化数据，则应该使用自定义类将数据存储在数据库中。您可以使用database+session+state+mode在Session+State中存储每个用户的信息。由于they+are+stored+in+memory,+not+the+database，ASP.NET应用程序状态/变量将不会对您有所帮助，因此它们也会在应用程序域重新启动时丢失。|243012^0|0|M|1Y|0|3X|U|1|0|K|V|2|0|2N|C|0|0|1C|F|3|0|0|0|0|0|0|0|10|4|0|1L|R|4|2D|D|5|33|17|6|0^^$0|$1|$2|3|4|5|6|$7|8]]|9|$2|3|4|5|6|$7|A]]|B|$2|3|4|5|6|$7|C]]|D|$2|3|4|5|6|$7|E]]|F|$2|3|4|5|6|$7|G]]|H|$2|3|4|5|6|$7|I]]|J|$2|3|4|5|6|$7|K]]]|L|@$M|N|O|P|2|Q|R|1U|S|@]|T|@]|6|$]]|$M|U|O|V|2|Q|R|1V|S|@]|T|@$W|1W|X|1X|M|1Y]|$W|1Z|X|20|M|21]]|6|$]]|$M|Y|O|Z|2|Q|R|22|S|@]|T|@$W|23|X|24|M|25]]|6|$]]|$M|10|O|11|2|Q|R|26|S|@$W|27|X|28|12|13]]|T|@]|6|$]]|$M|14|O|15|2|16|R|29|S|@]|T|@]|6|$17|18]]|$M|19|O|1A|2|Q|R|2A|S|@]|T|@$W|2B|X|2C|M|2D]]|6|$]]|$M|1B|O|1C|2|Q|R|2E|S|@]|T|@]|6|$]]|$M|1D|O|1E|2|1F|R|2F|S|@]|T|@]|6|$]]|$M|1G|O|1H|2|1F|R|2G|S|@]|T|@]|6|$]]|$M|1I|O|1J|2|1F|R|2H|S|@]|T|@]|6|$]]|$M|1K|O|1L|2|1F|R|2I|S|@]|T|@]|6|$]]|$M|1M|O|1N|2|1F|R|2J|S|@]|T|@]|6|$]]|$M|1O|O|1P|2|Q|R|2K|S|@$W|2L|X|2M|12|1Q]]|T|@]|6|$]]|$M|1R|O|1S|2|Q|R|2N|S|@]|T|@$W|2O|X|2P|M|2Q]|$W|2R|X|2S|M|2T]|$W|2U|X|2V|M|2W]]|6|$]]|$M|1T|O|-4|2|Q|R|2X|S|@]|T|@]|6|$]]]]

Static variables persist for the life of the app domain. So the two things that will cause your static variables to 'reset' is an app domain restart or the use of a new class. In your case with static variables stored in an aspx Page class, you may be losing the static variables when ASP.NET decides to recompile the aspx Page into a new class, replacing the old page class with the new one.

For those reasons if the system decide to restart or replace the class (<a href="http://blogs.msdn.com/b/jasonz/archive/2004/05/31/145105.aspx" rel="noreferrer">.NET doesn't kill or unload classes/assemblies in a running app domain</a>) then your static variables will reset because you are getting a new class with the restart or replacement. This applies to both aspx Pages and <a href="http://msdn.microsoft.com/en-us/library/t990ks23%28v=vs.80%29.aspx" rel="noreferrer">classes in the App_Code folder</a>

ASP.NET will replace a class if for any reason thinks that need to recompile it (<a href="http://msdn.microsoft.com/en-us/library/ms366723%28v=vs.100%29.aspx" rel="noreferrer">see ASP.NET dynamic compilation</a>).

You can't prevent the loss of static variables from an app domain restart, but you can try to avoid it from class replacement. You could put your static variables in a class that is not an aspx page and is not in the App_Code directory. You might want to place them on a <code>static class</code> somewhere in your program.

<pre><code>public static class GlobalVariables
{
 public static int SomeGlobalUnsecureID;
 public static string SomeGlobalUnsecureString;
}
</code></pre>

The static variables are per pool, that is means that if you have 2 pools that runs your asp.net site, you have 2 different static variables. (<a href="http://msdn.microsoft.com/en-us/library/aa479328.aspx" rel="noreferrer">Web garden mode</a>)

The static variables are lost if the system restarts your asp.net application with one of this way.

<ol>
<li>the pool decide that need to make a recompile. </li>
<li>You open the app_offline.htm file </li>
<li>You make manual restart of the pool </li>
<li>The pool is reach some limits that you have define and make restart. </li>
<li>For any reason you restart the iis, or the pool.</li>
</ol>

This static variables are not thread safe, and you need to use the lock keyword especial if you access them from different threads.

Since an app restart will reset your statics no matter what, if you really want to persist your data, you should store the data in a database using custom classes. You can store information per-user in <a href="http://msdn.microsoft.com/en-us/library/ms178581%28v=vs.100%29.aspx" rel="noreferrer">Session State</a> with a <a href="http://msdn.microsoft.com/en-us/library/ms178586%28v=vs.100%29.aspx" rel="noreferrer">database session state mode</a>. ASP.NET Application State/Variables will not help you because <a href="http://msdn.microsoft.com/en-us/library/ms178594%28v=vs.100%29.aspx" rel="noreferrer">they are stored in memory, not the database</a>, so they are lost on app domain restart too.

entityMap|blocks|key|243014|text|静态变量用于存储相同值的所有对象|type|unstyled|depth|inlineStyleRanges|entityRanges|data|243015|protected+void+Page_Load(object+sender,+EventArgs+e)
{
++++sss+s1,+s2;
++++s1+=+new+sss();
++++s1.TotalMark+=+10;
++++s2+=+new+sss();
++++s2.TotalMark+=+20;
++++sss.SchoolName+=+"St.Joseph's+Hr.Sec.S";+//We+can+access+through+class+and+assign+common+to+all
++++s1.PrintData();
++++s2.PrintData();
}

public+class+sss
{
++++public+static+string+SchoolName+{+set;+get;+}
++++public+int+TotalMark+{+set;+get;+}
++++public+string+StudentName{set;get;}
++++public+void+PrintData()
++++{
++++++++Console.WriteLine(TotalMark);
++++++++Console.WriteLine(SchoolName);
++++++++Console.WriteLine(StudentName);
++++}
}|code-block|syntax|javascript|243016^0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|I|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|J|9|@]|A|@]|B|$F|G]]|$2|H|4|-4|6|7|8|K|9|@]|A|@]|B|$]]]]

Static variable is used to store the all the object for same value

<pre><code>protected void Page_Load(object sender, EventArgs e)
{
 sss s1, s2;
 s1 = new sss();
 s1.TotalMark = 10;
 s2 = new sss();
 s2.TotalMark = 20;
 sss.SchoolName = "St.Joseph's Hr.Sec.S"; //We can access through class and assign common to all
 s1.PrintData();
 s2.PrintData();
}

public class sss
{
 public static string SchoolName { set; get; }
 public int TotalMark { set; get; }
 public string StudentName{set;get;}
 public void PrintData()
 {
 Console.WriteLine(TotalMark);
 Console.WriteLine(SchoolName);
 Console.WriteLine(StudentName);
 }
}
</code></pre>

entityMap|blocks|key|244459|text|我认为以下两点对于静态变量的生命周期也很重要：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|244460|1-在应用程序池的高级设置中，检查“循环”->“常规时间间隔(分钟)”设置。它的默认值是1740，这意味着在每29小时内，您的静态变量会因为应用程序池的回收而丢失。此设置用于终止可能的内存泄漏。我不会更改此设置..|244461|2-在应用程序池的高级设置中，检查“进程模型”->“空闲超时(分钟)”设置。它的默认值是20，这意味着在应用程序池中每20分钟处于不活动状态时，工作进程将终止/挂起，这将导致静态变量丢失。此设置用于在一段时间内未使用应用程序池时释放资源。您可以将其设置为0以禁用超时。|244462^0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|I|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|J|9|@]|A|@]|B|$]]|$2|G|4|-4|6|7|8|K|9|@]|A|@]|B|$]]]]

I think the following two points are also important for the lifetime of static variables:

1 - In your application pool's advanced settings check "Recycling" -> "Regular Time Interval (minutes)" setting. It's default value is 1740 which means in each 29 hours your static variables are lost because of recycling of your application pool. This setting is used for termination of possible memory leaks. I would not change this setting..

2 - In your application pool's advanced settings check "Process Model" -> "Idle Time-out (minutes)" setting. It's default value is 20 which means in each 20 minutes of inactivity in your application pool, the worker processes are terminated/suspended which will cause your static variables to be lost. This setting is used for freeing up resources when the application pool is not used in some amount of time. You can set it to 0 to disable the timeout.

I am holding some information in static variables defined in page class (not in Global.asax). I only declare variable in code like:

<pre><code>protected static int SomeGlobalUnsecureID;
protected static string SomeGlobalUnsecureString;
</code></pre>

and define the variable in PageLoad event. For example, I check ID from the database, if it's different from SomeGlobalUnsecureID, I update SomeGlobalUnsecureID and String from somewhere else, otherwise leave them as is. This is perfectly safe in my app. logic (i.e. those data are not secure, everybody can access them, no problem); only thing I want to accomplish is 

<ol>
<li>Hold the same amount of memory regardless of users connected</li>
<li>Change if and only if persistent info is different from the one in
'memory' (because actually reading the string is time consuming for
me.</li>
</ol>

Now, since I make the check in PageLoad, I have no problems in reloaded pages. However my page is full of WebMethods, and sometimes I see that the static variables are zeroed. And the strange part is; the session is still active even when the static variables are zeroed (so-> no server or app. pool restart etc.)

This is really strange for me. I assume that static variable will hold its value until the application (somehow) ends. But even the Session did not expire, the static variable is zeroed. What do you suggest? Is using application variables a better choice? All documents I've read on web suggest static variables instead of application variables, do I need to declare them somehow different?

Lifetime of ASP.NET Static Variable

数据存储

数据库

服务器

我在页面类(而不是Global.asax)定义的静态变量中保存了一些信息。我只在如下代码中声明变量：protected static int SomeGlobalUnsecureID;protected static string SomeGlobalUnsecureString;并在PageLoad事件中定义变量。例...

问ASP.NET静态变量的生存期
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