If I have a WCF service hosted in an Azure webrole, how many small machine instances would I need to spin up so that potentially 1000 clients could be connected at once?
Processing power is not the issue I'm concerned about, just the maximum number of active connections that Azure will allow me to have open at any given moment.
We have a service method that will take some time to complete (say 20-30 seconds) and we need to know roughly how many open connections Azure will allow us to have per small instance so we can ensure 1000 people man connect at once.
Thanks!
The limit #Jordan refers to is the number of IIS threads that can be active. Following #Jordan's link to here you will see that the IIS threads will get passed off to .Net threads while .Net is handling them.
Your .Net threads are effectively limited by the resources on the system, although 1000 might be OK. Better would be to pass the requests off to asynchronous handlers (if you can - I don't know what you are trying to do), which leaves only the maximum number of open TCP connections Windows Server 2008 R2 will allow, which should not be a problem for 1000 connections.
Existing answers mostly cover it, but a different type of answer is that Windows Azure doesn't care how many connections you have. Your question then becomes one about Windows and IIS/.NET/WCF or whatever technology you choose to use.
Looks like for .NET 3.5 it was 12, and in .NET 4.0 it's 5,000. Not sure how they decided on those numbers.
source: http://social.msdn.microsoft.com/Forums/en-US/windowsazure/thread/a6a4213b-b402-4a6c-940c-10937e34d9b5/
There is no limit with Azure Webrole - the only limits are whatever you've purchased - things like CPU, RAM, bandwith.
Related
Let's assume the following situation:
I have a database server that uses 4 core CPU;
My machine has 2 core CPU;
Assume they are of equal speed in terms of GHZ;
Systems are connected over a network (two lines 200mb/s each);
Test tool that I use provides # of threads parameter and will issue commands in parallel to the server.
QUESTIONS:
How would you test parallel reads/writes via stored procedure? Please brainstorm as any advice is appreciated;
How can I prove that many threads are executing the queries on the server (or should I not pay attention to this as this servers and DB's responsibility)?
What controls how many threads are executed at any time primarily in case of SQL server? I checked the "server properties" > processors > # of processors and threads section - waht more should I check?
How can I check that my application truly executes on all my machine cores - in other words - uses real threads instead of virtual ones? Or should I pay attention only to the virtual ones?
Should I pay attention to the network bandwidth? Can it be a bottleneck (I dont' send any big data, only commands with variables).
1.) not sure perhaps someone else can answer
2.) SQL Sentry allows you to monitor your SQL activity (use the free trial and buy if you like it)
3.) Max Dop controls the number of processors & also the cost threshold will affect parrallelism
4.) Same as 2 perhaps, i'm not sure i understand
5.) Depends on what you are doing are where you see aproblem SQL sentry will show wait stats that may help
We are currently setting up nServiceBus in a distributor/worker model and I was wondering if it is really worth it for us.
In our initial test lab, I have 2 clustered distributors and one worker (more workers in prod). What I am wondering is if it would be just as effective to leverage our high availability SQL Server for storage and rebuild the servers to all handle the work instead of having dedicated distributors and workers. All of our messages get onto the bus via a simple .Net Web API service. I could install that service on each box along with the endpoint dlls and have them all talk to SQL server which has more than enough horsepower to handle the load. We have a load balancer available to us to distribute the messages to the handlers.
What would some of the drawbacks be in taking this approach vs the distributor model?
What has me concerned is a line from David Boike's book on nServiceBus (great book BTW) that I just read...
"Using SQL Server as a transport can be a great choice for small
projects on teams that already use SQL Server"
The small projects part is what I am worried about. This is by no means a small project and it will have a pretty high volume of messages flowing through this layer as we refactor more systems to be message driven.
Has anyone been down the same road comparing SQL server to distributor and where did you come out?
Thanks
What I was referring into the book on the quote you mentioned was that there are times when you have a fairly small solution, all in a single SQL Server database, and you want to introduce some messaging around the edges. The SQL Server transport makes it easy to do that without adding a bunch of additional overhead and moving parts. If you keep everything in one database, you can even ditch the Distributed Transactions Coordinator. It can also be really useful for integrating with a legacy system where you monitor for changes via database triggers.
However, keep in mind (and if there's a next edition, I'll be sure to go into a little more detail about this) that the SQL Server transport uses a Broker pattern, that is, all communication must go through SQL Server so it becomes a central point of failure and a central bottleneck. The default MSMQ transport, on the other hand, follows the Bus architectural style, meaning it's completely decentralized. Each endpoint can run completely on its own, at least until you introduce additional dependencies.
Andreas benchmarked the new transports, and found that on V4 MSMQ was capable of roughly 6000 sends/s and 2300 receives/s, and that SqlServer was on par with that, but on MSMQ that is roughly per server (each server gets its own throughput), with the SQL Server transport that is going to be your total achievable throughput, period, and any endpoints you add will have to share it.
Of course, broker-style transports (the rest of the new transports in 4.0 are brokers too) do have some advantages over MSMQ. The biggest is that you don't need to use the Distributor to scale out. In a broker, the "queue" is centralized so you can simply spin up additional endpoints pointing at the same input queue in a competing consumers pattern.
Of course as in all things, your mileage may vary, but if you are planning an ambitious system, then the SQL Server transport may not be for you, as you will at some point get mired down in that point where your only option is to scale up your SQL Server instance.
I have a .NET application (VB.NET) that runs against a MS Access database. Every data request connects to the access database, runs and returns the query and closes the connection back again.
I placed the database on a windows xp 32-bit machine.
I have two clients on which I installed the .NET application. Both clients are running windows 7 professional 32-bit.
Now I have a performance problem with this.
When I use the first client it runs fine. All data is shown very fast. When I than use the second client, it takes some 10 seconds to connect to the database, fetch the data and close the database connection. When i ask for other data on that second client, it all runs fine, until I request data from the first client than back again. Than it takes again 10 seconds on the first client before my data is fetched.
Can anybody please help me with that? I owe a Belgian beer to the solver of this issue ;-)
Thanks!
Tom Wickerath wrote a great article on improving multiuser performance for MS Access applications. While his article assumes a MS Access front-end, many of the tips should apply to a .Net application. I recall two points that might help you:
Keep a persistent connection to the back-end
Use (short) UNC paths instead of mapped drives
After a long search, i found it out... My virusscanner NOD32 was causing this, most probably by excessive scanning inbound and outbound network traffic.
I'm not sure stackoverflow is the right place for questions like this, but ...
It sounds like the first process is locking the file, so the second process has to wait.
"Use SQL Server" isn't a completely flippant response - SQL Server is specifically designed to handle concurrency issues like this.
IMHO ...
PS:
This is a pretty lame link, but it might help:
http://office.microsoft.com/en-us/access-help/about-sharing-an-access-database-on-a-network-mdb-HP005240860.aspx
PPS:
Here's a somewhat better link, with some suggestions for things you can do to improve concurrency:
http://www.softcoded.com/web_design/upgrading_access.php
I am new to weblogic server. I am using work manager. I want to know what is work manager and why we need it. What is the difference between normal request with out work manager and with work manager !!
I think the documentation is rather good on this subject.
WebLogic Server prioritizes work and allocates threads based on an
execution model that takes into
account administrator-defined
parameters and actual run-time
performance and throughput.
Administrators can configure a set of
scheduling guidelines and associate
them with one or more applications, or
with particular application
components. For example, you can
associate one set of scheduling
guidelines for one application, and
another set of guidelines for other
application. At run-time, WebLogic
Server uses these guidelines to assign
pending work and enqueued requests to
execution threads.
Essentially, with work managers you can attach a scheduling policy to an application to e.g. make sure that a specific application gets a fair share of the available computing resources under a heavy load situation. Or you might want to restict the maximum number of threads that will be allocated to an application to prevent a buggy/untested application to bring the whole application server to its knees. (But surely all apps have been tested not to do anything like that.... ;) )
Outside of modifying the default allocation algorithms, the Work Manager is also useful if you are using a Foreign JMS Provider (such as IBM MQ) and need to process more than 16 messages at a time.
I'm planning on hosting 3 or 4 WCF/.NET 3.5 REST webservices to be used by a new iPhone application.
I've heard good reviews about DiscountASP.NET (http://www.discountasp.net/index.aspx), but I'm pretty ignorant about shared hosting performance. At the same time, I think it's still early to pay $90 a month for a scalable Amazon EC2 server instance.
So, any idea how many hits/month would a shared hosting website handle?
It depends on how good your shared hosting is. To determine simultaneous users, you can try to benchmark the performance of your server by hitting with many requests.
Your host will likely yell at you if they see you using a lot of your cpu. For web services, bandwidth isn't so much an issue as is your cpu/memory availability.
You should be more concerned about simultaneous users instead of hits per month. You want to be able to handle any spikes in traffic. Shared hosting is less predictable because you don't control the usage of the other users on the machine.
I would say if you're starting out, shared hosting would probably be fine, just monitor it and upgrade when you see decreasing response times. Your host will probably let you know when you are affecting the performance of everyone else on the server.
They are all different. It depends on how much bandwidth they are giving you. (GB/Month is a typical metric).
I would say that hits per month could range in the low hundred thousands without causing major issues on many managed hosting. It all depends how intenst your WCF services are. The advantage is that many managed hosting facilities will allow you to dynamically add more hosting power to your site. (For more $ obviously).