isolation

问题 With repeatable read isolation level, it is still possible to lose updates (second lost updates problem). E.g. in the scenario with isolation level set to RR: 1) transaction t1 reads data from row r1, 2) transaction t2 reads same data from row r1, 3) t1 modifies the data read in #1 and commits data to r1 4) t2 modifies the data read in #2 and commits data to r1. t1's update is lost I tried this with Hibernate (isolation level set to RR) and saw the behavior as mentioned above. Why then is it

问题 In linux where I work mostly, we use a technique called CPU isolation, that effectively locks a process on to a processor and also prevents the processor from running anything else. Our kernel guys did some magic to handle the interrupts. In windows the closest thing I found is an affinity concept which appears to bind a process/thread to a processor. But it makes no guarantee that the processor is ONLY running that process/thread meaning there can still be context switch and other jitter. Is

问题 I have a need to allow my users to execute .NET code that they provide on my server. I know security is a big concern, but it has to be done that way. Currently, I run my users' code under a limited Windows account. But, I am worried that .NET framework provides many classes that, if used maliciously, can harm the server -- classes under the Reflection namespace is one example, CodeDom is another concern. I wish there was a way to create a "lightweight virtual environment" that can run .NET

问题 I have a need to allow my users to execute .NET code that they provide on my server. I know security is a big concern, but it has to be done that way. Currently, I run my users' code under a limited Windows account. But, I am worried that .NET framework provides many classes that, if used maliciously, can harm the server -- classes under the Reflection namespace is one example, CodeDom is another concern. I wish there was a way to create a "lightweight virtual environment" that can run .NET

问题 In more detail, the question is: without root permission , is it possible for a process to read (not only write) the memory of another process? (eg. by somehow reading /proc/gcore or /proc/[PID]/mem. I'm not sure their permission requirements yet.) I do understand that virtual address is implemented and each process has its own space. I did a quick search but find neither strong guarantees nor approaches to hack. This article says: Each process in the system has its own virtual address space.

问题 Just a thought, but would using an IFRAME over a DIV essentially make that element isolated from the window in a way that slow scripts running in the IFRAME wouldn't affect the other frames/window? 回答1: Yes for the first part, an iframe will "sort-of" isolate your window from the script in the iframe. However, the parent window can still be accessed via window.parent . For the second part: No, it will not make it so slow scripts in the iframe won't affect other frames/windows. Your main

问题 I'm looking for pointers and information here, I'll make this CW since I suspect it has no single one correct answer. This is for C#, hence I'll make some references to Linq below. I also apologize for the long post. Let me summarize the question here, and then the full question follows. Summary: In a UI/BLL/DAL/DB 4-layered application, how can changes to the user interface, to show more columns (say in a grid), avoid leaking through the business logic layer and into the data access layer,

问题 I wrote a Google Chrome extension, which popups a dialog with an autocomplete field and it's own style, but there are some sites where my CSS gets totally broken, which doesn't look very nice. I know about isolating styles with iFrames, but in Google Chrome extension there is no way to isolate my HTML and CSS in this way. Another method is to wrap all my stuff into a separated div with it's own id and relative styles for that id, and I do so, but it seems that it doesn't work on some sites

问题 Here's something I've thought about for a while. I am creating an application where's my users will upload their own custom themes, which means that there's going to be a good opportunity for anyone with basic PHP/XSS/whatever skills to cause a lot of headache. I would like to run any uploaded files in a sort-of sandboxed, closed environment that only has access to the stuff (variables) that I want and nothing else. Would this be good practice and how would it be done? 回答1: To allow arbitrary

问题 If I had a 1000 asp.net websites each with 30 DLL's in their /bin folders. Therefore 30,000 DLL's. Would the websites / web server / machine run faster if I registered one set of the DLL's into the Global Assembly Cache and each site used the DLL's in the GAC? e.g. would the websites collectively use less memory? 回答1: Even though assemblies are in the GAC they will still be loaded from there into memory separately to provide isolation. In other words, just because assemblies are in the GAC