You're welcome Richard,
Please feel free to post here if there're anything else we can help.
Steven Cheng
Microsoft Online Support
Get Secure!
www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)
--------------------
| From: "Richard P" <
[email protected]>
| References: <
[email protected]>
<
[email protected]>
<#
[email protected]>
<
[email protected]>
| Subject: Re: Timer question
| Date: Wed, 21 Sep 2005 11:32:10 +0100
| Lines: 200
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| X-Tomcat-NG: microsoft.public.dotnet.general
|
| Steven
|
| I'll give that a go. Thanks a lot
|
| Richard
|
|
| | > Hi Richard,
| >
| > Thanks for your prompt response.
| > Yes, using RemoveCallBack is ok , however since you're put many longrun
| > operations in it, I'm not sure whether this has kill your app's
| > throughput.
| > Also, it seems that the reason you use RemoveCallBack now is just need
to
| > rerequest the in memory RSS(or can I use refresh? I think it's rather
| > exactly what you do, yes?)
| >
| > If so, I think you can consider use a separate background thread to do
the
| > work. when adding RSS content retrieved from remote url into application
| > Cache, you can event not specify a expiration timeout. And create a
| > background thread in Application_Start time which will refresh the
cached
| > RSSs in the cache once every certain time period. To create such as
| > background thread, you can just using the System.Threading.Thread to
| > construct a thread and a global ThreadProc , after start, store the
| > thread's reference in the applicationStates or be held in a global
| > variable(static vartiable). Thus, all the RSS retrieving operations is
| > done in the background thread, totally nothing related to threadpool
| > thread.
| >
| > Thanks,
| >
| > Steven Cheng
| > Microsoft Online Support
| >
| > Get Secure!
www.microsoft.com/security
| > (This posting is provided "AS IS", with no warranties, and confers no
| > rights.)
| >
| >
| > --------------------
| > | From: "Richard P" <
[email protected]>
| > | References: <
[email protected]>
| > <
[email protected]>
| > | Subject: Re: Timer question
| > | Date: Tue, 20 Sep 2005 07:53:24 +0100
| > | Lines: 115
| > | X-Priority: 3
| > | X-MSMail-Priority: Normal
| > | X-Newsreader: Microsoft Outlook Express 6.00.2900.2180
| > | X-RFC2646: Format=Flowed; Original
| > | X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180
| > | Message-ID: <#
[email protected]>
| > | Newsgroups: microsoft.public.dotnet.general
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| > 86.129.127.92
| > | Path: TK2MSFTNGXA01.phx.gbl!TK2MSFTNGP08.phx.gbl!TK2MSFTNGP12.phx.gbl
| > | Xref: TK2MSFTNGXA01.phx.gbl microsoft.public.dotnet.general:50273
| > | X-Tomcat-NG: microsoft.public.dotnet.general
| > |
| > | Hi Steven,
| > |
| > | Thanks for your reply. So from what you say CacheItemRemovedCallback
is
| > the
| > | most efficient of the three timer options because wait operations
create
| > no
| > | additional load. The CLR automatically polls the cache for expired
items
| > and
| > | only starts a threadpool thread when its time to execute the callback.
| > | Threading.Timer and RegisterWaitForSingleObject will each spawn an
extra
| > | thread on the thread pool to perform a wait operation and then spawn
| > another
| > | thread to run the callback.
| > |
| > | The request triggered method you recommend is what I am currently
doing.
| > The
| > | problem is that when throughput is low, the response times can be
quite
| > | slow - even though I fire the RSS requests in parallel.
| > |
| > | It seems to me therefore that it is ok to create any number (within
| > reason)
| > | of short term or long term CacheItemRemovedCallbacks, because no
| > additional
| > | load is created for the wait operations. The key issue is to avoid
| > | congesting the threadpool with loads of callback operations,
| > particularly
| > if
| > | each operation is long-running and non-CPU intensive, such as when
| > | requesting a remote RSS feed.
| > |
| > | Please let me know if I've got this wrong.
| > |
| > | thanks
| > |
| > | Richard
| > |
| > |
| > |
| > | | > | > Hi Richard,
| > | >
| > | > Welcome to MSDN newsgroup.
| > | > AS for the Timer question you mentionded, here are some of my
| > | > understanding
| > | > and suggestions:
| > | >
| > | > For the ASP.NET's Cache entry's RemoveCallback function, generally
| > they're
| > | > called when the underlying background polling thread found an
certain
| > | > cache
| > | > item expired, and this background thread is not necessarily a thread
| > pool
| > | > thread, of course we don't worry that removecallback function will
| > consume
| > | > many thread pool thread. However, since the background polling
| > thread(for
| > | > checking cache expireation) is important, we'd recommend that we
don't
| > put
| > | > two many tasks (long run ) in removecallback handler.
| > | >
| > | > Also, I don't suggest that we use ThreadPool's
| > RegisterWaitForSingleObject
| > | > or other methods to do the work since they'll occupy threadpool
| > threads
| > | > which is important for serving asp.net requests. In fact, my
| > suggestion
| > | > is just let the items expire and rerequest them on the next request
| > from
| > | > page, and retrieve them from remote url and cache in the memory
cache.
| > | > Just like:
| > | >
| > | > //////////
| > | > If (Cache[key] == null)
| > | > {
| > | > //retrieve from remote place and insert into cache
| > | > }
| > | >
| > | > return Cache[key];
| > | > /////////
| > | >
| > | > Thanks,
| > | >
| > | > Steven Cheng
| > | > Microsoft Online Support
| > | >
| > | > Get Secure!
www.microsoft.com/security
| > | > (This posting is provided "AS IS", with no warranties, and confers
no
| > | > rights.)
| > | > --------------------
| > | > | From: "Richard P" <
[email protected]>
| > | > | Subject: Timer question
| > | > | Date: Mon, 19 Sep 2005 19:42:00 +0100
| > | > | Lines: 18
| > | > | X-Priority: 3
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| > | > | Message-ID: <
[email protected]>
| > | > | Newsgroups: microsoft.public.dotnet.general
| > | > | NNTP-Posting-Host: host86-129-136-61.range86-129.btcentralplus.com
| > | > 86.129.136.61
| > | > | Path:
| > TK2MSFTNGXA01.phx.gbl!TK2MSFTNGP08.phx.gbl!TK2MSFTNGP15.phx.gbl
| > | > | Xref: TK2MSFTNGXA01.phx.gbl microsoft.public.dotnet.general:50240
| > | > | X-Tomcat-NG: microsoft.public.dotnet.general
| > | > |
| > | > |
| > | > | I need some help on timers. My app is asp.net 1.1 website running
in
| > a
| > | > | shared hosting environment with a third-party service provider. I
| > | > currently
| > | > | request and cache 20 - 40 remote RSS feeds. When a user requests
the
| > | > page,
| > | > | the app first tries to retrieve a feed from cache, if the feed
has
| > | > expired,
| > | > | it goes off and request the file from the web.
| > | > |
| > | > | If create a CacheItemRemovedCallback for each item to
automatically
| > | > | re-request an expired cached page, will I clog up the ThreadPool?
| > | > |
| > | > | Would I be better off using Threading.Timer or
| > | > | ThreadPool.RegisterWaitForSingleObject?(although I far as I can
tell
| > | > both
| > | > | methods create wait operations on threadpool threads)
| > | > |
| > | > | Richard
| > | > |
| > | > |
| > | > |
| > | > |
| > | >
| > |
| > |
| > |
| >
|
|
|
