synchronization

问题 I need to use PHP to copy data from one MySQL database to another. I can build and array of all the values to go into the other database but first I want to make sure the database has the correct fields before inserting. For example say I am going to be copying data from tableA to tableB. I can set up tableB to look just like tableA but in the future I may add columns to tableA and forget to add them to tableB, then my PHP script will try to insert data into a column that doesn't exist in

问题 Is there a read/write locking mechanism that works across processes (similar to Mutex, but read/write instead exclusive locking)? I would like to allow concurrent read access, but exclusive write access. 回答1: No. As Richard noted above, there is no such out of the box mechanism in .NET. This is how to implement it using a mutex and a semaphore. Method #1 is described in http://www.joecheng.com/blog/entries/Writinganinter-processRea.html, quoting: // create or open global mutex GlobalMutex

问题 Another synchronization question...I hope you guys don't get annoyed ;) Assume the following scenario: one central data structure (very large, so I don't really want to make it immutable and copy it around whenever a change occurs. I even don't want to keep multiple copies in memory), multiple reader threads that access that data structure read-only and one writer thread which keeps the data structure up to date in the background. I currently synchronize all accesses to the data structure,

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . does anybody know some free tool for synchronization MySQL database (data and structure) like in Navicat for Windows ? I'm using

问题 This question already has answers here : Java Equivalent of .NET's ManualResetEvent and WaitHandle (4 answers) Closed last year . What is java's equivalent of ManualResetEvent? 回答1: The closest I know of is the Semaphore. Just use it with a "permit" count of 1, and aquire/release will be pretty much the same as what you know from the ManualResetEvent . A semaphore initialized to one, and which is used such that it only has at most one permit available, can serve as a mutual exclusion lock.

问题 I have an extension where users maintain a list of links. It would be nice to have this data synchronized between computers (at work and at home). What are the possible solutions? Chrome has extension synchronization option but I am not sure if it synchronizes data or not (I would be surprised if yes). Even if it does, not everyone would want all their other extensions be synced. I can store my links in a special bookmark folder and use built-in bookmark synchronization, but in this case all

问题 according to Eric Gunnerson Don’t Use lock(this) Use lock(typeof()) Do Lock on a private variable, not on something the user can see Use “object key = new object()” if you need a private key to lock on what is the reason?? 回答1: what is the reason?? Because anything that is not private means that could be used from the outside to lock on by someone else or some code that is outside from your control leading to deadlocks. The best practice is to lock on private static variables, like this:

问题 I have searched a lot but not able to find particular solution. There are also some question regarding this on stackoverflow but i am not able to find satisfactory answer so i am asking it again. I have a class as follow in java . I know how to use threads in java. //please do not consider syntax if there is printing mistake, as i am typing code just for showing the concept in my mind public class myclass{ private List<String> mylist=new ArrayList<String>(); public addString(String str){ /

问题 I have a problem with a deadlock in my code related to the use of condition variables. This is more of a design question than a pure code question. I have no problem actually writing code once I understand the correct design. I have the following scenario: Thread A waits on a condition variable. Thread B calls notify_all, and thread A wakes up. This is of course what I want to happen, and is what does happen when everything works as expected. But sometimes, I get the following scenario

问题 Since I've started programming in Java I have been wondering this (about a year or two). In C, we must know the different method to correctly avoid deadlock between thread and thus there is much more choice between synchronization method. So what about Java? When we synchronize, how does it avoid putting thread in deadlock situation? How does it work internally? Does the deadlock are avoided because we synchronized on higher level than in C ( or C++)? Any documentation about deadlock and