Hi,
I am developing an application which will be served to more than hundred of
users in one second.
Of course, this is a roughly way of telling my case in an example like this.
Because the system will be served many users it has to be use any database
queries as seldom
as possible. So, I found a simple solution for this: I will save my frequently
used data in an object
hierarchy for accessing to it easily and in an oop way, then I will load it on
each hour. Any update to
the data from the web-pages will be saved when hourly schedule comes into the
place. Actually webpages
had to be in touch with the database for their updating progress, but in my
solution, they will be in touch with
the cached data. And update will be occured as I stated earlier, when the hourly
schedule comes.
Because this is the case, I somehow should be ensure about synchronizing the
data. When the
hourly schedule gets in I will have to be lock up the entire object hierarchy.
But this can be
problematic when it is think in the way of the time it would take. But I found
another simple
solution for this: I will load the data from the database and save it into my
new object hierarchy.
When it has loaded, I will lock the shared object hierarchy and exchange the new
object hierarchy
with the old one. Then all the request will be used the newly object hierarchy
while the older one is
waiting the garbage collector.
I made some tests about the locking behaviour in web pages those were written
with asp.net. I put
a "static" dummy locker object into the global.asax.cs for sharing the lock over
the entire application
domain (I know this may not be necessary but it has came to me as the clearest
possible solution at
that time).
In those tests, I realized that, even whether I acquire the lock or not, pages
are synchronize their
actions somehow. I realized that by looking the results those were generated
from my code. A one
page has took the lock when my shared dummy integer varible was 0 and released
it when it was 5000.
Another has took the lock when the var was 5000 (the state where the first one
acquired the lock), and released
it when it was 10000 and another one has took when it was 10000.....and so....
The sample code about this can
be found at the end of the message.
I will store my objects in the cache object that was presented by asp.net
framework. As I know, the cache
enters the critical region automatically when it has manipulating (like updating
or removing the data from the
cache) by some code. Because of this reason the lock for the cache may be even
unnecessary.
And the last question of mine is that, if I ever be need to use a locking
schema, which one the superior
"for this situation". I am thinking to use ReaderWriterLock locking technique
because the 'writing' operations
occure least than 'reading' operations. What do you think?..
So guys, I will be very appreciated if I can hear your comments about the case.
Best regards, thank you.
Inanc Gumus
------------
in some page:
------------
// I know this locking scheme is not efficient one
// but this code only for this small testing and actually
// who cares..
#define ACQUIRE_LOCK
private void Page_Load(object sender, System.EventArgs e)
{
Response.Write(String.Format("I have started at {0}<br />",
DateTime.Now.ToString());
Response.Write(String.Format("My executer thread code is {0}<br />",
System.Threading.Thread.CurrentThread.GetHashCode().ToString());
ulong last = 0;
Response.Write(String.Format("I got it when it was {0}<br />",
Global.DummyVar.ToString());
for (ulong i = 0; i < 500000000; i++)
{
#if ACQUIRE_LOCK
lock (Global.DummyLock)
{
#endif
last = Global.Incr();
#if ACQUIRE_LOCK
}
#endif
}
Response.Write("And now its value is "+ last.ToString() +"<br />");
Response.Write("I have finished at "+ DateTime.Now +"<br />");
}
------------
in global.asax.cs:
------------
private static object dummyLock = new object[0];
private static ulong dummyVariable = 0;
public static object DummyLock
{ get { return dummyLock; } }
public static ulong DummyVar
{ get { return dummyVariable; } }
public static ulong Incr()
{ return ++dummyVariable; }
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