I am studying various ASP.Net deployment approaches. In there, I got a basic question. Is there any thumb rule about enviornment definition? What could be called a 'good' setup if I have to support 1000 concurrent users(requests).
I understand that there are many factors like how application is designed etc. But assuming that everything else is great, what configuration should I look for like Which processor, how much RAM etc?
Also how many concurrent users below configuration should be able to support ?
CPU: Dual 3.40 GHz Intel Xeon (Hyper-Threaded)
Memory : 3GB
OS: Windows Server 2003 SP2
Thanks for thelp
Having been on both sides of the equation (web developer and hardware engineer), my current opinion is that the answer involves both of those sides as well.
Your hardware needs to be not only sufficient for general usage, but it also has to cope with reasonable unexpected peaks and failures - which means that it needs to be redundant, and in excess of your capacity planning.
Your software needs to be designed so its easily redundant - theres no point in speccing a tiered hardware architecture (now or for future planning) if the software is going to require significant amount of changes to handle it.
Your software also needs to be designed so sudden unexpected peaks in resource usage don't happen as a regular occurrence for no external reason (eg marketing campaign).
I know that you say you understand the non-hardware factors, but the real answer to your question is that there is no real way to answer it without knowing the other factors - each situation and circumstance is unique, and requires a unique solution.
However, in an effort to add generalised recommendations, try these:
CPU - choose something with a lot of cache, and individual cache per core as well. This will do wonders to speed up the system. I typically go for dual core, dual processor at a minimum (for a total of 4 cores on two seperate physical cpus). Processor speed ratings don't really matter as much as you think these days.
Memory - fast memory, minimum of 8GB of it. Use the smallest dimms possible for the server.
Harddisk - SAS 15K RPM at a minimum, RAID 6 for the data partition on one controller, RAID 1 or 6 for the system partition on another controller. Choose a good quality controller backed by a good support or warranty package - your controller is no good if it dies in 3 years time and you can't get a replacement.
But above all, don't just install the OS and app and let it be, profile the set up as much as possible, don't be afraid of making changes to optimise to the individual setup (within reason). Move your ASP.Net temporary files to a fast disk (or a ram disk - if they are going to be rebuilt anyway, no matter worrying over losing them). Move the database to a second server, with a crossover 1GBit link between the two. Turn off disk maintenance in the OS, turn off services you do not need.
Good luck!
Related
We got a high traffic website which generates a lot of I/O. Within 10 minutes it has been reading over 10 gb of data (w3wp in question seen in task manager). For memory and application hangs I have been using WinDbg with success. But I don't know how I can find the object(s) / method(s) within a process which are responsible for the highest I/O.
Is this even possible?
Edit
The question is: Is there a way to profile I/O operations in a .NET assembly, say: list of threads sorted by highest disk I/O (or something similar that would help me where to look)
ANTS Performance Profiler
I have used this tool to great success - dealing with finding the specific instructions which are causing ~512GB of memory on a high-volume web farm getting chewed up within 5-10 minutes. Sounds like a very similar situation as yours.
Now, to be realistic - it's not going to magically solve your problem. It still requires a lot of setup, thorough analysis and detective work. But this tool definitely took the problem from "practically unsolvable" to "solvable within days".
Update:
As I mentioned in the comments (and Ben Emmett echoed), we can use ANTS to monitor memory, file system handles - pretty much any resource consumption and drill down the call stack to see the effects of specific routines.
I came up with this tool AppDynamics Lite which displays your application calls costs and performance in a visual way. It might help you to find out which functions are making the most costy IO operations.
Quoting;
Understand the health of your CLR with key metrics like response time, throughput, exception rate, and garbage collection time as well as key system resource like CPU, memory and disk I/O.
Worth giving a shot as it is trial/free for 30 days. Hope it helps.
Ps: I'm not affiliated with AppDynamics in any way.
You can use the (free) Windows Performance Toolkit from Windows 8 which does run also on Windows Vista and later. There you can turn on system wide profiling to see what was going on in all processes at once. No instrumentation necessary. Only one reboot is required to set an arcane registry key which is done by WPRUI.exe automatically.
With XPerf you could enable IO Init stack walking so that a call stack is taken for every IO which is started. The only issue is that the stacks will be broken for 64 bit processes which means that you will see only the first method above the BCL methods of your code because there is a Windows 7 bug in the stackwalking capabilities of the OS.
A workaround is to Ngen your assemblies or move to Server 2012 or switch to x86 for profiling to see deeper call stacks.
You will see all file IO and CPU activity even without any call stacks and the file names along how long the hard disc was used. That should give you good information which part of your app is causing the disc IO. From the partial call stacks you should be able to pinpoint your issue even without full stacks.
The tool will give you much more insight than any commercially available profiler at the expense that you need to learn how to use it. Since the call stacks do not end at your code or in user mode but in the kernel you can also determine if e.g. the virus scanner is causing significant IO delays. But you need to know how your processor does work. This toolset was originally aimed at kernel devs which explains why you see so many useless columns.
In the picture below you see file IO and CPU consumption stacked. When you select your high IO file in the disc IO graph it will highlight in the CPU consumption all related call stacks which were taken at the same time while the IO was active. This way you can diretly navigate from the IO to your potentially blocked threads.
I'm currently working on a fairy large project (active members is about hundreds K) and was strongly lean to Plone solutions.
I've asked some questions related to it like here and here.
Got some replies from very experienced Plonistas (and active stackoverflowers as well). I really appreciate it. People keeps saying Plone does not scale well to that large, and most of the reasons is because of ZODB.
Then I think of an in-memory backend for ZODB. RAM is really cheap now ! you can get 128GB for just ~$3k, ten times over a normal $300 128GB SSD, and achieve ~30GBs IO bandwidth compare to that ~300MBs of the SSD.
in-memory backend + Blob for binary + 10s disk journalling for backup + all undos except last 10s would be an instance kill ! They should smoke the RDBMs and offer full ACID + Transaction + Object Mapping compare to such couch*/redis etc.
Is it technical possible ? Is there any implementation ? Does it worth implement (in your opinion) ?
There is a memcache option for RelStorage which helps when you need to use a slow database, but really you should probably just leave that sort of caching to your operating system and make sure your database server has plenty of RAM. (If your RAM is large enough then your filesystem cache should already store most of the data.)
An SSD will significantly reduce the worst case read latencies for random access to data not already in the filesystem cache. It seems silly not to use them now, especially as the Intel 330 SSD is so cheap and has a capacitor equivalent to a battery backed raid controller (making writes superfast too.)
An all in RAM solution can never be considered ACID, as it won't be Durable.
As mentioned in my comment on your other post, it is not the ZODB that is the problem here but Plone's synchronous use of a single contended portal_catalog.
Instead of keeping the entire ZODB in memory, you could mount the portal_catalog in a separate mount point and keep it in memory. I've already seen such kind of configuration and it works smoothly for about 8k users using standard hardware (2 server + 1 zeo server). It may be sufficient for your needs, maybe using more performant hw.
I'm profiling a asp(classic) web service. The web service makes database calls, reads/writes to files, and processes xml. On a windows server 2003 box(2.7ghz, 4 core, 4gb ram) how many requests per second should I be able to handle before things start to fail.
I'm building a tool to test this, but I'm looking for a number of requests per second to shoot for.
I know this is fairly vague, but please give the best estimate you can. If you need more information, please ask.
95% of the performance of any data-driven app is dependent on the database: 1) the way you do your calls, 2) the indexes, 3) the hardware under the database (disk subsystem in particular).
I have seen a machine, like you are describing, handle 40 requests per second (2500/minute), but numbers like 10 per second (600/minute) are more common. I would expect even lower if you are running your DB on the same machine, and even lower still if that DB is SQLExpress or MSAccess.
Also, at capacity, your app will probably not fail, but IIS will Queue requests, once it is saturated, and may timeout some of those requests if it can't service them before the timeout expires.
Btw, instead of building a tool to test your app, you may want to look into using a test tool such as Microsoft WCAT. It is pretty smooth and easy to use.
How fast should it be? Fast enough.
How fast is fast enough? That's a question that only you and your users can answer. If your service is horrifically inefficient and keeps up with demand, it's fast enough. If your service is assembly-optimized, lightning-fast, and overwhelmed with requests, it's not fast enough.
If the server is handling its actual workload, then don't worry about how fast it "should" be. When the server is having trouble, or when you anticipate that it soon will, then you should look at improving the code or upgrading the hardware. Remember Knuth's Law – premature optimization is the root of all evil. Any work you do now to make it faster may never pay off, and you may be forced to make compromises with flexivility or maintainability. Remember, too, an older adage – if it ain't broke, don't fix it.
Yes I would also say 10 per second is a good benchmark. For a high performance app you would want to get more than this, but if you have no specific goal you should generally be able to get at least 10 requests per sec for a general web page with a bunch of database queries.
I want to use the highest possible number of threads (to use less computers) but without making the bottleneck to be in the client.
JMeter can simulate a very High Load provided you use it right.
Don't listen to Urban Legends that say JMeter cannot handle high load.
Now as for answer, it depends on:
your machine power
your jvm 32 bits or 64 bits
your jvm allocated memory -Xmx
your test plan ( lot of beanshell, post processor, xpath ... Means lots of cpu)
your os configuration (tunable)
Gui / non gui mode
So there is no theorical answer but following Best Practices will ensure JMeter performs well.
Note that with jmeter you can distribute load through remote testing, read:
Remote Testing > 15.4 Using a different sample sender
And finally use cloud based testing if it's not enough.
Read this for tuning tips:
http://www.ubik-ingenierie.com/blog/jmeter_performance_tuning_tips/
Read this book for doing load testing and using JMeter correctly.
I have used JMeter a fair bit and found it is not great at generating really high load. On a 2Ghz Core2 Duo with 2Gb memory you can reasonably expect about 100 threads.
That being said, it is best to run it on your hardware so that the CPU of the PC does not peak at 100% - a stable 80%-90% is best otherwise the results are affected.
I have also tried WAPT 5 - it successfully ran 1000+ threads from the same PC. It is not free but it is more useable than JMeter but doesn't have all of the features.
Outdated answer since at least version 2.6 see https://stackoverflow.com/a/11922239/460802 for a more up to date one.
The JMeter Wiki reports cases where JMeter was used with as much as 1000 threads. I have used it with at most 100 threads, but the Links in the Wiki suggest resource reductions I never tried.
One of the issues we had with running JMeter on Windows XP was the Windows XP TCP Connection Limit. Limit should be removed in order to run use the JMeter to workstation’s full potential
More info here. AFAIK, does not apply to other OS.
I used JMeter since 2004 and i launched lot of load tests.
With PC Windows 7 64 bits 4Go RAM iCore5.
I think JMeter can support 300 to 400 concurrent threads for Http (Sampler) protocol with only one "Aggregate Report Listener" who writes in the log file results and timers between call pages.
For a big load test you could configure JMeter with slaves (load generators) like this
http://jmeter-plugins.org/wiki/HttpSimpleTableServer/
I have already done tests with 11 PC slaves to simulate 5000 threads.
I have not used JMeter, but the answer probably depends on your hardware. Best bet might be to establish metrics of performance, guess at the number of threads and then run a binary search as follows.
Source was Wikipedia.
Number guessing game...
This rather simple game begins something like "I'm thinking of an integer between forty and sixty inclusive, and to your guesses I'll respond 'High', 'Low', or 'Yes!' as might be the case." Supposing that N is the number of possible values (here, twenty-one as "inclusive" was stated), then at most questions are required to determine the number, since each question halves the search space. Note that one less question (iteration) is required than for the general algorithm, since the number is already constrained to be within a particular range.
Even if the number we're guessing can be arbitrarily large, in which case there is no upper bound N, we can still find the number in at most steps (where k is the (unknown) selected number) by first finding an upper bound by repeated doubling. For example, if the number were 11, we could use the following sequence of guesses to find it: 1, 2, 4, 8, 16, 12, 10, 11
One could also extend the technique to include negative numbers; for example the following guesses could be used to find −13: 0, −1, −2, −4, −8, −16, −12, −14, −13
It is more dependent on the kind of performance testing you do(load, spike, endurance etc) on a specific server (a little on hardware dependency)
Keep in mind around these parameters
- the client machine on which you are targeting the run of jmeter, there will be a certain amount of heap memory allocated, ensure to have a healthy allocation so that the script does not error out. The highest i had run on jmeter was 1500 on a local environment ( client - server arch), On a Web arch, the highest i had a run was based upon Non- functional requirement were limited to 250 threads,
so it ideally depends on the kinds of performance testing and deployment style and so on..
There is not standard number for this. The maximum number of threads that you can generate from one computer depends completely on the computer's hardware and the OS. The OS by default occupies certain amount of CPU and the RAM.
To find out the maximum threads your computer can handle you can prepare a sample test and run it with only a few threads. Then with each cycle of test run increase the number of threads gradually. During this you also need to monitor the CPU, RAM, Disk I/O and Network I/O of your computer. The moment any of these reach near or beyond 80% (Again for you to decide if near is okay for you or beyond), that is the maximum number of threads your computer can handle. To be on the safer side I would stop at the number when the resource utilization reaches 70%.
It'll depend on the hardware you run on as well as the underlying script. I've always felt that this fuzziness is the biggest problem with traditional load testing tools. If you've got a small budget ($200 or so gets you a LOT of testing), check out my company's load testing service, BrowserMob.
Besides our Real Browser Users (RBUs) which control thousands on actual browsers for the purpose of performance and load testing, we also have traditional virtual users (VUs). Scripts are written in JavaScript and can make various HTTP calls.
The reason I bring it up is that I always felt that the game of trying to figure out how many VUs you can fit on your load gen hardware is dangerous. It's so easy to get bad results without realizing it.
To solve that for BrowserMob, we took an extremely conservative approach on the number of VUs and RBUs per CPU core: no more than 1 browser or 50 threads per CPU core, and sometimes much less. In the world of cloud computing, CPU cycles are so cheap that it just doesn't make sense to try to overload machines.
How much traffic can one web server handle? What's the best way to see if we're beyond that?
I have an ASP.Net application that has a couple hundred users. Aspects of it are fairly processor intensive, but thus far we have done fine with only one server to run both SqlServer and the site. It's running Windows Server 2003, 3.4 GHz with 3.5 GB of RAM.
But lately I've started to notice slows at various times, and I was wondering what's the best way to determine if the server is overloaded by the usage of the application or if I need to do something to fix the application (I don't really want to spend a lot of time hunting down little optimizations if I'm just expecting too much from the box).
What you need is some info on Capacity Planning..
Capacity planning is the process of planning for growth and forecasting peak usage periods in order to meet system and application capacity requirements. It involves extensive performance testing to establish the application's resource utilization and transaction throughput under load. First, you measure the number of visitors the site currently receives and how much demand each user places on the server, and then you calculate the computing resources (CPU, RAM, disk space, and network bandwidth) that are necessary to support current and future usage levels.
If you have access to some profiling tools (such as those in the Team Suite edition of Visual Studio) you can try to set up a testing server and running some synthetic requests against it and see if there's any specific part of the code taking unreasonably long to run.
You should probably check some graphs of CPU and memory usage over time before doing this, to see if it can even be that. (A number alike to the UNIX "load average" could be a useful metric, I don't know if Windows has anything like it. Basically the average number of threads that want CPU time for every time-slice.)
Also check the obvious, that you aren't running out of bandwidth.
Measure, measure, measure. Rico Mariani always says this, and he's right.
Measure req/sec, RAM, CPU, Sessions, etc.
You may come up with a caching strategy (Output caching, data caching, caching dependencies, and so on.)
See also how your SQL Server is doing... indexes are a good place to start but not the only thing to look at..
On that hardware, a .NET application should be able to serve about 200-400 requests per second. If you have only a few hundred users, I doubt you are seeing even 2 requests per second, so I think you have a lot of capacity on that box, even with SQL server running.
Without know all of the details, I would say no, you will not see any performance improvement by adding servers.
By the way, if you're not using the Output Cache, I would start there.