synchronization

问题 I just found the following OpenGL specification for ARB_map_buffer_range. I'm wondering if it is possible to do non-blocking map calls using this extension? Currently in my application im rendering to an FBO which I then map to a host PBO buffer. glMapBuffer(target_, GL_READ_ONLY); However, the problem with this is that it blocks the rendering thread while transferring the data. I could reduce this issue by pipelining the rendering, but latency is a big issue in my application. My question is

问题 I'm looking to implement data synchronization between servers and distributed clients. The data source on the server is mysql with django on top. The client can vary. Updates can take place on either client or server, and the connection between server and client is not reliable (eg. changes can be made on a disconnected cell phone, should get sync'd when the cell phone has a connection again). S. Lott suggests using a version control design pattern in this question, which makes sense. I'm

问题 My web application returns a file from the filesystem. These files are dynamic, so I have no way to know the names o how many of them will there be. When this file doesn't exist, the application creates it from the database. I want to avoid that two different threads recreate the same file at the same time, or that a thread try to return the file while other thread is creating it. Also, I don't want to get a lock over a element that is common for all the files. Therefore I should lock the

问题 My web application returns a file from the filesystem. These files are dynamic, so I have no way to know the names o how many of them will there be. When this file doesn't exist, the application creates it from the database. I want to avoid that two different threads recreate the same file at the same time, or that a thread try to return the file while other thread is creating it. Also, I don't want to get a lock over a element that is common for all the files. Therefore I should lock the

问题 I have a service that runs in the background which can access (read and write) to sqlite database. The corresponding foreground process (main app) can also access (read and write) to sqlite database in my android application. How can i prevent problems related to trying to access / save / read at the same time to/from sqlite db and what should be the correct way to do this? 回答1: There are 2 easy ways to do this, the first as ChirstopheCVB writes: Create a synchronized method. A synchronized

问题 I'm trying to understand how threads work, and I wrote a simple example where I want to create and start a new thread, the thread, display the numbers from 1 to 1000 in the main thread, resume the secondary thread, and display the numbers from 1 to 1000 in the secondary thread. When I leave out the Thread.wait()/Thread.notify() it behaves as expected, both threads display a few numbers at a time. When I add those functions in, for some reason the main thread's numbers are printed second

问题 I want to create a project in which it is required to synchronize local database with remote database. Changes made in local database must be reflected to remote database. This must be done synchronously. I have application which does CRUD operations on local database written in java/jpa. Synchronization should be triggered from java code. I thought of triggers on each table of database which will maintain changes in local database. But I doubt its secure or not. After googling I found out

问题 Say that I update values of two variables in a synchronized method. Would it be possible that the new values set in synchronized method be visible to other threads before exiting the synchronized block? public synchronized void setValues(){ a=5; // assume thread is preempted after this assignment // would the value 5 be visible to other threads? // my understanding is that the values will not be flushed to // main memory until the lock is released- i.e., until the synchronized // method is

问题 According to Controlling startup order in Compose, one can control the order in which Docker Compose starts containers by using a "wait-for-it" script. Script wait-for-it.sh expects both a host:port argument as well as the command that the script should execute when the port is available. The documentation recommends that Docker Compose invoke this script using the entrypoint: option. However, if one uses this option, the container will no longer run its default ENTRYPOINT or CMD because

问题 According to Controlling startup order in Compose, one can control the order in which Docker Compose starts containers by using a "wait-for-it" script. Script wait-for-it.sh expects both a host:port argument as well as the command that the script should execute when the port is available. The documentation recommends that Docker Compose invoke this script using the entrypoint: option. However, if one uses this option, the container will no longer run its default ENTRYPOINT or CMD because