synchronization

Is there any difference in performance between this synchronized void x() { y(); } synchronized void y() { } and this synchronized void x() { y(); } void y() { } chrylis Yes, there is an additional performance cost, unless and until the JVM inlines the call to y() , which a modern JIT compiler will do in fairly short order. First, consider the case you've presented in which y() is visible outside the class. In this case, the JVM must check on entering y() to ensure that it can enter the monitor on the object; this check will always succeed when the call is coming from x() , but it can't be

On a busy ASP .NET website, I have a Dictionary, which acts as a cache, basically storing key/value pairs for later retrieval. On high load, the Dictionary some times get into a state, where it always throws an IndexOutOfRangeException whenever i call the ContainsKey or Add method. The exception happens inside the private FindEntry method. I am suspecting that this might be due to a synchronization issue, but I am not sure. Can anyone tell me under which circumstances this can happen ? My goal is to gather enough information so that I can reproduce the issue in the dev environment. The

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 tableB and it will fail. So what I want to do is compare tableA to tableB and any columns that tableA has

I'm trying to create a basic following algorithm using Swift and Firebase. My current implementation is the following: static func follow(user: FIRUser, userToFollow: FIRUser) { database.child("users").child(user.uid).observeSingleEventOfType(.Value, withBlock: { (snapshot) in var dbFollowing: NSMutableArray! = snapshot.value!["Following"] as! NSMutableArray! dbFollowing?.addObject(userToFollow.uid) self.database.child("users/"+(user.uid)+"/").updateChildValues(["Following":dbFollowing!]) //add user uid to userToFollows followers array in similar way }) { (error) in print("follow - data could

The following bit of code does exactly what I want, except it only prints to the console. cmd := exec.Command("php", "randomcommand.php") cmd.Stdout = os.Stdout cmd.Stderr = os.Stderr if err := cmd.Run(); err != nil { log.Fatal(err) } randomcommand.php: // randomcommand.php simply alternates output between stdout and stderr 20 times $stdout = fopen('php://stdout', 'w+'); $stderr = fopen('php://stderr', 'w+'); for ($i = 1;$i <= 20; $i++) { fwrite($stdout, "stdout $i\n"); fwrite($stderr, "stderr $i\n"); } Output: stdout 1 stderr 1 stdout 2 stderr 2 stdout 3 stderr 3 stdout 4 stderr 4 stdout 5

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, which works just fine (no synchronization effects, no deadlocks). What I don't like about this approach

I have a function that needs to be executed only when a callback is received from asynchronous function. Like I call asynchronous function Stop() and soon after that I call asynchronous function Start() . The Issue before Stop CallBack is received Start() is called and thus I am getting issues. Also I can not separate the calling of two functions Like I can not do this.: public void SomeFunction() { Stop(); } public void Stop_CallBack(eventargs e) { Start(); } I have to do this: public void SomeFunction() { Stop(); //Do something; Start(); } but before I receive Stop call back my start()