Skip to main content

Sistem stateless si sisteme stateful

By
Citeam un articol ce descria paraller programing. Si am ajuns la doi termeni care desi imi pareau cunoscuti nu imi erau foarte clar definiti.
Cei doi termeni sunt
  • stateless system;
  • stateful system;
Un sistem stateless este un sistem inchis, unde output-ul depinde doar de input si atata. Rezultatul obtinut nu este deloc influentat deloc de alte valori pe care sistemul le poate stoca intr-o forma sau alta.
In cazul acesta un exemplu ar putea sa fie:
Console.WriteLine(DateTime.UtcNow.ToString());
Oriunde pe glob ne-am afla si orice setare am aveam la masina( regional settings), valoarea returnata o sa fie aceiasi in orice locatie de pe glob. Acest sistem poate sa fie numit stateless din punct de vedere a regional settings.
Un sistem stateful este un sistem deschis, unde outpu-ul nu depinde doar de input. Pentru calcularea output-ului se i-au in considerare si alte valori. Poate fi vazut intr-o oarecare masura ca o masina de stari, care poate sa isi pastreze ultima stare.
Un bun exemplu este:
Console.WriteLine(DateTime.Now.ToString());
In functie de regional settings, o sa putem avea valori diferite afisate in zone diferite ale lumii, deoarece propietatea statica Now tine cont de regional settings.
Din punct de vedere a rularii in paralel, un sistem stateless este cel mai usor de implementat. Oricate thread-uri ar exista, acestea nu trebe sa partajeze/sincronizeze informatii. Fiecare isi poate face treaba cu input-ul pe care il are.
In cazul unui sistem stateful, programarea in paralel nu mai este atat de simpla. Pot sa apara cazuri cand mai multe resurse( stari ale masinii sau sistemului) sunt partajate intre mai multe theaduri, caz in care apare lucrurile se complica.
Labels:

Comments

Post a Comment

Popular posts from this blog

Windows Docker Containers can make WIN32 API calls, use COM and ASP.NET WebForms

By
After the last post , I received two interesting questions related to Docker and Windows. People were interested if we do Win32 API calls from a Docker container and if there is support for COM. WIN32 Support To test calls to WIN32 API, let’s try to populate SYSTEM_INFO class. [StructLayout(LayoutKind.Sequential)] public struct SYSTEM_INFO { public uint dwOemId; public uint dwPageSize; public uint lpMinimumApplicationAddress; public uint lpMaximumApplicationAddress; public uint dwActiveProcessorMask; public uint dwNumberOfProcessors; public uint dwProcessorType; public uint dwAllocationGranularity; public uint dwProcessorLevel; public uint dwProcessorRevision; } ... [DllImport("kernel32")] static extern void GetSystemInfo(ref SYSTEM_INFO pSI); ... SYSTEM_INFO pSI = new SYSTEM_INFO(...
Post a Comment
Read more

How to audit an Azure Cosmos DB

By
In this post, we will talk about how we can audit an Azure Cosmos DB database. Before jumping into the problem let us define the business requirement: As an Administrator I want to be able to audit all changes that were done to specific collection inside my Azure Cosmos DB. The requirement is simple, but can be a little tricky to implement fully. First of all when you are using Azure Cosmos DB or any other storage solution there are 99% odds that you’ll have more than one system that writes data to it. This means that you have or not have control on the systems that are doing any create/update/delete operations. Solution 1: Diagnostic Logs Cosmos DB allows us activate diagnostics logs and stream the output a storage account for achieving to other systems like Event Hub or Log Analytics. This would allow us to have information related to who, when, what, response code and how the access operation to our Cosmos DB was done. Beside this there is a field that specifies what was th...
Post a Comment
Read more

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

By
Today blog post will be started with the following error when running DB tests on the CI machine: threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration: TeamCity .NET 4.51 EF 6.0.2 VS2013 It see...
8 comments
Read more