This comes in reference to another question how does windows azure platform scale for my app? stating only multithreaded applications would benefit from multi-core architecture.
My question is that as ASP.NET/IIS (or any other web application and web server) is basically multi-threaded will it not take the advantage of multi-cores?
Assuming the site is a simple web application with some logic that is executed on page display without explicit multithreading implementation.
I believe it is for the console applications or schedules only that require multithreaded programming implemented for it to take advantage of multi cores, please advice.
IIS by design implementation takes full advantage of all available to the OS CPU cores. However it is really application specific to decide which VM size to choose. I barely see anything larger than Medium being used for a Web Role!
The most common case is to use Small VM for a Web Role and scale out to multiple instances when unnecessary. And I always advise customers to start with a Small VM, do some performance/load testing while closely monitoring the VM to assess the need for a larger one (if any). From resilience point of view, as well as durability, and in many cases even performance, it is much better to rely on 4 Small VMs, rather than 1 Large!
Keep in mind that it is always easier, and cost-wise to scale with a smaller step (1 or 2 CPU Cores at once, meaning Small or Medium VM).
There are many business requirements existing in this world that require multi-thread on web application such as generate data and insert it to DB, export excel via AJAX... With a small VM and a minimum RAM with powerful core, if you don't manage your logic well and take advantage of hardware, your RAM would run out shortly.
Related
I have a Windows Server 2012 with IIS 8.0. It is hosting many small websites with a low user base which are not mission critical in any way. With small website I mean that the application code and memory footprint is quite low, but due to the loaded libraries, like EntityFramework, the memory consumption of the applications are about 140MB when freshly started and idle.
In general that’s not a big deal for a full-blown webserver, but I only have a VPS with 4GB of RAM which also runs several other applications (databases, BIND, hMail, etc.). I’m using it basically as development server to play with many different technologies. Therefore, I’m running out of RAM quickly while serving dozens of ~140MB w3wp’s.
Beside of suspending when idle I’d like to reduce the memory consumption while still using any framework or library I’d like to use – that’s the purpose of the whole thing actually.
Long story short: As the applications not only share the same .NET version but also some libraries like EF or MVC, would it make more sense to run multiple sites in one app_pool so that they can share the libs? Or would each site load its own copy anyway (due to different Application domains like discussed here)?
Bonus question: when considering a hardware upgrade 1GB of RAM is 20$/month but putting the whole server on SSDs is 10$/month. While I do know that reading from page file is always much slower than reading from RAM I’m thinking about using a big pagefile on the SSD instead of buying 1gig of additional RAM for twice the price – again, speed of the websites isn’t critical, they should just work. Would that make any sense at all?
Looking at a w3wp Process (hosting multiple sites) in Process Explorer shows that it hosts several different application domains with different instances of the same assemblies loaded into memory. So moving the sites into a single AppPool may not help much.
But there is another option. In IIS 8+ you can share common assemblies across AppPools. If certain assemblies are used by multiple AppPools, they are loaded into memory just once and then aliased by the different processes.
Have a look at this bit from asp.net and this TechNet blog post
You have to do a little bit of setup work, but then it seems to work quite well.
I have an MVC4 web application that, when volume is put through it, consumes ~400MB RAM in all environments excluding the production environment. When a similar volume of load is put through it on a production server (hosted externally), the memory utilisation trebles to ~1.2GB and the memory isn't released even when the application is idle. The IIS configuration across all environments is the same.
Its also worth noting that the application, when idle, releases some of that memory in my test environments, but doesn't do the same in production. The RAM gradually increases and tops out at 1.2-1.3GB, but never drops below – even if traffic is completely routed away from the server.
I have not been able to recreate this issue on any other environment other than my third party hosting platform, but before I conclusively blame the infrastructure and get the hosting company on the case I wondered:
a) Is this a common problem and why does it happen
b) How can I see what is using the memory
c) Would you expect the same code to consume significantly different levels of system resources based on platform (I know my host may have monitoring etc. in production which will perhaps inflate a little)
Any help on this is appreciated.
This is a common problem which we normally face when we work on Different Environments. This is because System configuration, Windows etc differs from system to system.
In this particular case as we see its a big difference, probably there is some loops or memory is not freed at regular intervals.
Few steps:
Try to get root of the problem i.e. which method is taking time. Use Loggers like nlog.
Try using profilers if you are using Sql Server
And the third is use ants-performance-profiler
Also it depends on number of user hitting on site and some deadlock conditions.
There can be numerous reasons for the same.
Disclaimer: I'm a c# ASP.NET developer learning "RoR". Sorry if this question doesn't "get" RoR, any corrections greatly appreciated!
What is multithreading
My understanding of "multithread" ability in web apps is twofold:
Every time a web/app server receives a request it can assign a thread to the new request, thus multiple requests can run concurrently.
The app runtime + language allows for multiple threads to be used WITHIN a single request (in ASP.NET via "Async" methods and keywords for example).
In this way, IIS7 + ASP.NET can do points 1 AND 2.
I'm confused about RoR
I've read these two articles and they have left me confused:
Clearing up some things about LinkedIn mobile’s move from Rails to
node.js
How to deploy a multi-threaded Rails app
question one.
I think I understand that RoR doesn't lend itself very well to point number 2 above, that is, having multiple threads within the same request, have I got that right?
question two.
Just to be crystal clear, RoR app/web servers can also do point number 1 above right (that is, multiple requests can run concurrently)? is that not always the case with RoR?
Question 1:
You can spawn more Ruby threads in one request if you want, although that seems to be outside the typical use case for Rails. There are uses for it for certain long-running IO or external operations.
Question 2:
The limiting factor for Ruby concurrency in general, not just with Rails, is the Global Interpreter Lock. This feature of Ruby prevents more than 1 thread of Ruby from executing at any given time per process. The lock is released whenever there is non-Ruby code executing, such as waiting for disk IO or SQL responses. You can get around this by using a different implementation of Ruby than the default, such as JRuby, but not all.
Phusion Passenger uses process based concurrency to handle a few requests concurrently, so, strictly speaking, is not "multithreaded," but is still concurrent.
This talk from Ruby MidWest 2011 has some good thoughts on getting multithreaded Ruby on Rails going.
Since this is about "from ASP.NET to RoR" there is another small but important detail to remember: In *nix environments it's common to achieve concurrency of a service application through multi-processing rather than multi-threading. This is an architecture that goes way back and is related to the relatively cheap cost of multi-processing on *nix systems using fork and Copy-on-Write. Each process serves one request at a time in a single thread and the main process controls spawning and killing worker child processes. Multiple requests are served concurrently by different child processes.
Modern service applications, for example Apache, have multi-process, multi-threaded, and even combined modes (where the service forks several processes, each running several threads).
In cases where the application was built with portability at mind (examples again: Apache, MySQL, etc) it is customary to run it in multi-process or combined mode on *nix systems, and in multi-threaded mode on Windows servers.
However, admittedly Rails is somewhat lacking on the Windows front. It's not that you can't run it on Windows, it's just that not a lot of effort went into making sure it runs well and smoothly for production use on Windows servers. It's not a common production platform among the RoR community.
As a result, Eventhough Rails itself is thread-safe since version 2.2, there isn't yet a good multi-threaded server for it on Windows servers. And you get the best results by running it on *nix servers using multi-process/single-threaded concurrency model.
Rails as a framework is thread-safe. So, the answer is yes!
The second link that you posted here names many of the Rails servers that don't do well with multi-threading. He later mentions that nginx is the way to go (it is definitely the most popular one and highly recommended). But he doesn't mention what made him come up to the conclusions.
Ruby 1.9.3 came out recently and has some new threading goodness built in which didn't exist before.
Use of multi-threading generally depends on the use case.
Personally I have tried it once an year ago and it had worked but I haven't used it in any production code because I haven't come across a use case where using multi-threading made more sense over pushing the long running task to a background job.
I would love to explore this more. So, if you can describe what you are trying to achieve then maybe we can do a POC.
Until recently I'd considered myself to be a pretty good web programmer (coming up for 10yrs commercial experience on a variety of e-commerce, static and enterprise applications). I'm self taught and have always used the Microsoft product stack (ASP, ASP.NET)...
My applications are always functional, relatively bug free, but have never been lightening quick. As a frequent web user I always found this to be the norm... how fast are the websites from the big tech players (eBay, Facebook, Microsoft, IBM, Dell, Telerik etc etc) - in truth none are particularly fast. I always attributed this to "the way things are with web apps"...
...then I cam across a product called Jira from atlasian and this has stopped me in my tracks...
This application is fast, and I mean blindingly fast.. too fast to time the switches between pages, fully live content, lots of images and data and cross references etc etc...
I run this on an intranet, with a large application DB, and this is running on a very normal server (single processor, SATA HDD, 8GB RAM).
Am I missing something?? Are my programming techniques that bad?? I am wondering if this speed gain is down to it being written in Java and running on Tomcat.
Does anyone have any benchmarks to compare JSP / ASP or Tomcat / IIS???
Thanks,
Mark
NOTE: this isn't a blatant plug for Jira. I don't work for them or have any affiliation to them... but I would like to be able to write applications like them :)
YMMV. But one of the longest-lived Things That Aren't True Anymore is the assertion that "Java Is Slow". Excepting floating-point (where most Java implementations aren't at liberty to use the floating-point hardware), Java is generally as fast or faster than compiled code. Some of the best and brightest have spent years of effort ensuring this, including such things as dynamic recompilation/re-optimization of code based on run-time metrics - something that statically-compiled languages like C or assembler cannot boast.
ASP is sort of the opposite extreme, since the original ASP had to recompile each page request each and every time it was made. ASPX addressed this by allowing retention of the compiled page code. That got rid of a lot of useless overhead.
A more compelling reason to prefer Java over ASPanything/IIS is freedom. A Java/Tomcat webapp will run under almost any OS on almost any hardware. IIS runs on Windows. Period. And for the most part, that also means Intel. Not Sparc, Not zSeries. Maybe you don't care. But then again, maybe next week IBM will offer your employer a can't-refuse deal on a mainframe.
I don't have benchmarks, and there are a lot of things that can make one platform preferable. But I permanently gave up on the "Java is slow" idea when I encountered the Poseidon UML tool with its cool real-time graphics UI and the FreeMind mindmapper tool. A small hit to startup the JVM, but after that, you'd never know what language you were working under.
The great debate. Java vs. .Net.
When .Net first came out there was an application written called "The Pet Shop." Which was a .Net port of Sun's J2EE reference application, "The Pet Store". It was announced that Microsoft's implementation was "faster."
As with anything, especially anything to do with marketing, you have to dig deeper to find the truth.
Any technology can be fast with enough hardware and the correct design.
In my experience there are two factors to speed: What type of hardware is used and how you architect your application (this includes database tuning).
Caching at various levels (response, db, etc.) makes a huge different in responsiveness of a web application. There is also a lot of things that are done to reduce time consuming operations like db connection pooling, sql statement caching, etc. As much as I'd like to say Java is better :-), I think in this case the performance is due to the way Jira was written and the fact that it's being run internally (probably with few users as compared to eBay, Facebook, Microsoft). This site, Stackoverflow, uses ASP.NET MVC and IIS and is very responsive and my guess (since code is not open sourced, yet) is that they use many of the same techniques you would find in Jira or any other web application built to scale.
I think that it is not typically the frameworks and languages used that make an application slow. In my experience, some frameworks like JSF or .NET server side controls give developers alot of freedom to make too many database calls and look things up too often, but that's definitely not the fault of the framework used.
Keep your application as light as possible and focus on keeping the data sent to the client as small as possible, and you will have a fast application. It's usually faster to develop fast applications too.
The Jira folks have written a best in class application (and charge for it) - nice work crocodile dundees.
I also suggest to consider also two aspects:
the maintenance activities: logging and deployment. In my opinion under a unix like server is more easier to log, deploy, and maintain new release than doing the same on a Windows server.
if the project require to use some open source application (i.e. Alfresco repository) Java is better solutions
People's opinion is mostly biased. Most people have never really tried the other while claiming the other is slower. I wouldn't trust any answer: it's mere opinion. It's boring to always read the same 4 cents again and again.
So I've seen this question, but I'm looking for some more general advice: How do you spec out a build server? Specifically what steps should I take to decide exactly what processor, HD, RAM, etc. to use for a new build server. What factors should I consider to decide whether to use virtualization?
I'm looking for general steps I need to take to come to the decision of what hardware to buy. Steps that lead me to specific conclusions - think "I will need 4 gigs of ram" instead of "As much RAM as you can afford"
P.S. I'm deliberately not giving specifics because I'm looking for the teach-a-man-to-fish answer, not an answer that will only apply to my situation.
The answer is what requirements will the machine need in order to "build" your code. That is entirely dependent on the code you're talking about.
If its a few thousand lines of code then just pull that old desktop out of the closet. If its a few billion lines of code then speak to the bank manager about giving you a loan for a blade enclosure!
I think the best place to start with a build server though is buy yourself a new developer machine and then rebuild your old one to be your build server.
I would start by collecting some performance metrics on the build on whatever system you currently use to build. I would specifically look at CPU and memory utilization, the amount of data read and written from disk, and the amount of network traffic (if any) generated. On Windows you can use perfmon to get all of this data; on Linux, you can use tools like vmstat, iostat and top. Figure out where the bottlenecks are -- is your build CPU bound? Disk bound? Starved for RAM? The answers to these questions will guide your purchase decision -- if your build hammers the CPU but generates relatively little data, putting in a screaming SCSI-based RAID disk is a waste of money.
You may want to try running your build with varying levels of parallelism as you collect these metrics as well. If you're using gnumake, run your build with -j 2, -j 4 and -j 8. This will help you see if the build is CPU or disk limited.
Also consider the possibility that the right build server for your needs might actually be a cluster of cheap systems rather than a single massive box -- there are lots of distributed build systems out there (gmake/distcc, pvmgmake, ElectricAccelerator, etc) that can help you leverage an array of cheap computers better than you could a single big system.
Things to consider:
How many projects are going to be expected to build simultaneously? Is it acceptable for one project to wait while another finishes?
Are you going to do CI or scheduled builds?
How long do your builds normally take?
What build software are you using?
Most web projects are small enough (build times under 5 minutes) that buying a large server just doesn't make sense.
As an example,
We have about 20 devs actively working on 6 different projects. We are using a single TFS Build server running CI for all of the projects. They are set to build on every check in.
All of our projects build in under 3 minutes.
The build server is a single quad core with 4GB of ram. The primary reason we use it is to performance dev and staging builds for QA. Once a build completes, that application is auto deployed to the appropriate server(s). It is also responsible for running unit and web tests against those projects.
The type of build software you use is very important. TFS can take advantage of each core to parallel build projects within a solution. If your build software can't do that, then you might investigate having multiple build servers depending on your needs.
Our shop supports 16 products that range from a few thousands of lines of code to hundreds of thousands of lines (maybe a million+ at this point). We use 3 HP servers (about 5 years old), dual quad core with 10GB of RAM. The disks are 7200 RPM SCSI drives. All compiled via msbuild on the command line with the parallel compilations enabled.
With that setup, our biggest bottleneck by far is the disk I/O. We will completely wipe our source code and re-checkout on every build, and the delete and checkout times are really slow. The compilation and publishing times are slow as well. The CPU and RAM are not remotely taxed.
I am in the process of refreshing these servers, so I am going the route of workstation class machines, go with 4 instead of 3, and replacing the SCSI drives with the best/fastest SSDs I can afford. If you have a setup similar to this, then disk I/O should be a consideration.