locking

问题 We have had an issue with a block of code that responds poorly in the face of slow databases (It craps the bed on a query timeout). We have created a patch, and are in the process of running it through regression. We can't get a timeout. I've opened a transaction from SQL Mgmt Studio and updated every row to lock them, but that doesn't cause INSERTs to timeout (which is what I need). Can I get a table-level lock easily via T-SQL? Or do I have to fiddle around in master? Or can I easily force

问题 When is it appropriate to use either the Monitor class or the lock keyword for thread safety in C#? EDIT: It seems from the answers so far that lock is short hand for a series of calls to the Monitor class. What exactly is the lock call short-hand for? Or more explicitly, class LockVsMonitor { private readonly object LockObject = new object(); public void DoThreadSafeSomethingWithLock(Action action) { lock (LockObject) { action.Invoke(); } } public void DoThreadSafeSomethingWithMonitor(Action

问题 My Java program wants to read a file which can be locked by another program writing into it. I need to check if the file is locked and if so wait until it is free. How do I achieve this? The Java program is running on a Windows 2000 server. 回答1: Under Windows with Sun's JVM, the FileLocks should work properly, although the JavaDocs leave the reliability rather vague (system dependent). Nevertheless, if you only have to recognize in your Java program, that some other program is locking the

问题 This question already has answers here : Why does the lock object have to be static? (3 answers) Closed 2 years ago . Raleted to: Lock in static methods lock Statement please consider this code: public static class SomeClass { public static void Method1(string key, int item) { //Some Work } public static DataTable Method2() { //Some Work } .... If I want to use this class in Asp.Net application from performance point of view does it need separate lock object for every methods like this:

问题 This question already has answers here : Why does the lock object have to be static? (3 answers) Closed 2 years ago . Raleted to: Lock in static methods lock Statement please consider this code: public static class SomeClass { public static void Method1(string key, int item) { //Some Work } public static DataTable Method2() { //Some Work } .... If I want to use this class in Asp.Net application from performance point of view does it need separate lock object for every methods like this:

问题 I am new to Android Development. Now I want to integrate Fingerprint lock in my application. Which is the best. Please help me to find good fingerprint lock. 回答1: USING CAMERA AS FINGER LOCK as refernece check this Fingerprint Scanner using Camera As someone who's done significant research on this exact problem, I can tell you it's difficult to get a suitable image for templating (feature extraction) using a stock camera found on any current Android device. The main debilitating issue is

问题 I create about 10 threads doing the same work - downloading image from the Internet. After the download is completed it will raise this callback function: private void DownloadImageWrapper(IRestResponse response, params object[] args) { byte[] imageData = response.RawBytes; using (Stream ms = new MemoryStream(imageData)) { WriteableBitmap wbImg = PictureDecoder.DecodeJpeg(ms); callback.DynamicInvoke(wbImg, file); }; } The exception is thrown in line with WriteableBitmap. I read that lock will

问题 I was given a simple python program to analyze. It works fine, and outputs 13, 14, and 15 randomly (of course). I can see why 13 and 14 where printed, but I don't understand where 15 came from. Please explain. from threading import Thread import random import time import sys def rwait(): amt = random.uniform(0.01,0.1) time.sleep(amt) x = 0 key = True def lockx(): global key while not key: time.sleep(0) rwait() key = False def unlockx(): global key key = True def A(): global x rwait() lockx()

问题 I am working on a tiny Raspberry Pi cluster (4 pis). I have 3 Raspberry Pi nodes that will be leaving a message in a message.txt file on the head Pi. The head Pi will be in a loop checking the message.txt file to see if it has any lines. When it does I want to lock the file and then extract the info I need. The problem I am having is that I need to do multiple commands. The only ways I have found that allows multiple commands look like this... ( flock -s 200 # ... commands executed under lock

问题 I have written two lock-free update helper methods inspired by Joseph Albahari & Marc Gravell Looking at the 2nd implementation why would I need the SpinWait in the 1st implementation? What are the advantables/disadvantages of one over the other? Please note this question is not about what SpinWait does but rather specific to how these two methods differ in execution. public static void LockFreeUpdate1<T>(ref T field, Func<T, T> updater) where T : class { var spinner = new SpinWait(); T