copy-on-write

I have classes like below class A { @Override public boolean equals(Object other) { return true } } Class B extends A { } Class C extends A { @Override public boolean equals(Object other) { if ((other != null) || (other instanceOf B)) return false; } } In my main() I have this following code Set<A> mySet = new CopyOnWriteArraySet<A>(); mySet.add(C); I want mySet to contain C at this point mySet.add(B); // #1 I want mySet to contain C & B at this point mySet.remove(B); // #2 I want mySet to contain C at this point I want to create a global queue where if object C exists in the queue B should be

I read about copy-on-write implementation for Array in Swift here . Arrays, like all variable-size collections in the standard library, use copy-on-write optimization. Multiple copies of an array share the same storage until you modify one of the copies. When that happens, the array being modified replaces its storage with a uniquely owned copy of itself, which is then modified in place. Optimizations are sometimes applied that can reduce the amount of copying. I was wondering if you have any information about which structure supports copy-on-write. Copy-on write is supported for String and

How do I prevent the GC from provoking copy-on-write, when I fork my process ? I have recently been analyzing the garbage collector's behavior in Ruby, due to some memory issues that I encountered in my program (I run out of memory on my 60core 0.5Tb machine even for fairly small tasks). For me this really limits the usefulness of ruby for running programs on multicore servers. I would like to present my experiments and results here. The issue arises when the garbage collector runs during forking. I have investigated three cases that illustrate the issue. Case 1: We allocate a lot of objects

I want to know how copy-on-write happens in fork(). Assuming we have a process A that has a dynamical int array: int *array = malloc(1000000*sizeof(int)); Elements in array are initialized to some meaningful values. Then, we use fork() to create a child process, namely B. B will iterate the array and do some calculations: for(a in array){ a = a+1; } I know B will not copy the entire array immediately, but when does the child B allocate memory for array? during fork()? Does it allocate the entire array all at once, or only a single integer for a = a+1 ? a = a+1; how does this happen? Does B

I distinctly remember from the early days of .NET that calling ToString on a StringBuilder used to provide the new string object (to be returned) with the internal char buffer used by StringBuilder. This way if you constructed a huge string using StringBuilder, calling ToString didn't have to copy it. In doing that, the StringBuilder had to prevent any additional changes to the buffer, because it was now used by an immutable string. As a result the StringBuilder would switch to a "copy-on-change" made where any attempted change would first create a new buffer, copy the content of the old

I am getting an exception when I try to remove elements from CopyOnWriteArrayList using an iterator. I have noticed that it is documented Element-changing operations on iterators themselves (remove, set, and add) are not supported. These methods throw UnsupportedOperationException. (from http://download.oracle.com/javase/6/docs/api/java/util/concurrent/CopyOnWriteArrayList.html ) Now, surprisingly i can iterate it with foreach and use the remove() function . But then I get the famous bug - when trying to remove an item from a list using a for loop - you skip the element next to the removed