c# - why my HttpContext.Application variable cannot be access through different Actions in ASP.NET MVC -

i created aspnet mvc program, , want variables can shared every visitor.
typed code global.asax:

protected void application_start(){      smequeue[] smetime = new smequeue[10];     application["waittime"] = smetime; ... 

however, can't modify array in application. can read in every actions in contyoller this:

smequeue[] arr = system.web.httpcontext.current.application["waittime"] smequeue[]; 

but after change values in array in action, in other actions still original array assigned in global.asax. modification cannot pass other actions.
why , can do?
found there many similar questions on stackoverflow, sadly answers not work mine.

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more codes:
i edit variable in action:

public actionresult create()     {         smequeue[] arr = system.web.httpcontext.current.application["waittime"] smequeue[];         arr[0] = new smequeue("hello");//elements of arr null before 

then access action:

public actionresult tryconnect()     {         smequeue[] arr = system.web.httpcontext.current.application["waittime"] smequeue[];         request.write(arr[0].tostring());//it' null. 

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if assign value variable in application_start(), can access value anywhere (any actions). after modify value in action, read in other actions still value assigned in application_start().

you first need understand application objects created more once. therefore different requests may using different application objects. makes sense 1 action reading start values rather modified values because being handled different application objects.

disadvantages of application state:

application scope scope of application state can disadvantage. variables stored in application state global particular process application running in, , each application process can have different values. therefore, cannot rely on application state store unique values or update global counters in web-garden , web-farm server configurations.

asp.net state management recommendations

a classic example encounter iis winding down application due inactivity default 20 minutes believe. when next request hits server new worker process spun new application object , therefore state.

so if need maintain state beyond single session , application, need form of state persistence, typically database, write/read through too.

i using:

• httpcontext short lived per user per request storage
• cookies long lived per user multi request storage
• cache long lived multi user, multi request data
• application state global lookup data doesn't (daily, weekly, monthly) bearing in mind you'll have manage wind down, spin old new data.
• and reaching out db or other efficient read/write medium type of thing seem trying / page counters etc.

to test of put breakpoint on application_start code , see how many times gets hit, every time that's new application object in play.... plus looking @ threads in debug windows of vs can informative.