synchronization

问题 I need to use a global mutex to synchronize access to a mutually shared file by several processes. I create the mutex as such: HANDLE hMutex = ::CreateMutex(NULL, FALSE, L"Global\\MySpecialName"); And then use it in: //Entering critical section VERIFY(::WaitForSingleObject(hMutex, INFINITE) == WAIT_OBJECT_0); and then: //Leave critical section VERIFY(::ReleaseMutex(hMutex)); The issue arises from the fact that the processes sharing this mutex are a local-system service and several user-mode

问题 Given the following code: public class SomeClass { private boolean shouldBlock = false; private Object resource; public void handleDrawRequest(Canvas canvas) { if (!shouldBlock && resource == null) { shouldBlock = true; loadTheResource(); //which takes awhile shouldBlock = false; } else if (shouldBlock && resrouce == null) { return; //another thread is taking care of the loading of the resource //and its not ready yet, so just ignore this request } drawResourceOn(canvas); } } How can I make

问题 Numba Cuda has syncthreads() to sync all thread within a block. How can I sync all blocks in a grid without exiting the current kernel? In C-Cuda there's a cooperativeBlocks library to handle this case. I can't find something like that in the Numba Docs. Why this matters a lot ! This sort of thing happens in reductions where one computes something in each block, then you want to find the maximum over the blocks. Trivially one could push these into the stream as two separate calls. This

问题 Numba Cuda has syncthreads() to sync all thread within a block. How can I sync all blocks in a grid without exiting the current kernel? In C-Cuda there's a cooperativeBlocks library to handle this case. I can't find something like that in the Numba Docs. Why this matters a lot ! This sort of thing happens in reductions where one computes something in each block, then you want to find the maximum over the blocks. Trivially one could push these into the stream as two separate calls. This

问题 I am working on a PHP class implementing PDO to sync a local database's table with a remote one. The Question I am looking for some ideas / methods / suggestions on how to implement a 'backup' feature to my 'syncing' process. The ideas is : Before the actual insert of the data takes place, I do a full wipe of the local table's data. Time is not a factor so I figure this is the cleanest and simplest solution and I wont have to worry about checking for differences in the data and all that jazz.

问题 So let's say I have a class X with a method m. Method m is NOT synchronized and it doesn't need to be since it doesn't really change the state of the object x of type X. In some threads I call the method like this: x.m(). All these threads use the same object x. By how many threads can be this method (method m) called on object x simultaneously? Can be the fact that the method is called by, let's say, 100 threads a bottleneck for my application? thanks. 回答1: Other's have answered your direct

问题 Normally in applications (Take web application for example) we have a single instance of the logger created during the startup. It can even be a singleton and it doesn't matter. The important thing is there is 1 instance for the whole application. We use java.util.logger Now image you have two requests from two different users which throw an exception and we are logging those which get written to the log file. Is the write in these two different requests to the log file synchronized in

问题 I would like to know what are ruby's alternatives to the Java methods : wait notify notifyAll Could you please post a small snippet or some links ? 回答1: With the caveat that I don't know Java, based on your comments, I think that you want a condition variable. Google for "Ruby condition variable" comes up with a bunch of useful pages. The first link I get, seems to be a nice quick introduction to condition vars in particular, while this looks like it gives a much broader coverage of threaded

问题 I would like to know what are ruby's alternatives to the Java methods : wait notify notifyAll Could you please post a small snippet or some links ? 回答1: With the caveat that I don't know Java, based on your comments, I think that you want a condition variable. Google for "Ruby condition variable" comes up with a bunch of useful pages. The first link I get, seems to be a nice quick introduction to condition vars in particular, while this looks like it gives a much broader coverage of threaded

问题 I notice that with MS Sync, going through the wizard to create the WCF service that will do the sync, you can only choose which table to sync. Is it possible to only sync a few columns of the table and not the entire table? It will also create the local sdf file with the whole table structure. I only need a few columns of the table to be displayed in my mobile device. 回答1: You can achieve this by writing code. You can use the DbSyncTableDescription DbSyncTableDescription tableDescription =