Making an array or dictionary a value type by definition, but then actually copying it only when one reference to it tries to modify it is a lovely idea, but it makes me wary in a multi-queued/thre...

According to mmap() manpage: MAP_PRIVATE Create a private copy-on-write mapping. Updates to the mapping are not visible to other processes mapping the same file, and are not carried through t...

So I have a simple cow_ptr. It looks something like this: template<class T, class Base=std::shared_ptr<T const>> struct cow_ptr:private Base{ using Base::operator*; using Base::opera...

This question contains some proposals for working around the problem, I would like to understand more in depth that exactly the problem is: QList<QString> q; for (QString &x: q) { .. } ...

I know that swift will optimize to copy on write for arrays but will it do this for all structs? For example: struct Point { var x:Float = 0 } var p1 = Point() var p2 = p1 //p1 and p2 share the ...

I've got the following function: func checkFiles(path string, excludedPatterns []string) { // ... } I'm wondering, since excludedPatterns never changes, should I optimize it by making the var g...

My filesystem (FS) (ZFS specifically) supports copy-on-write (COW), i.e. a copy (if done right) is a very cheap constant operation, and does not actually copy the underlying content. The content is...

As I continuously write data to redis, the memory used by copy-on-write keeps increasing. Even though I write my program to sleep long enough so that redis will be able to finish all the background...

I would like to know what copy-on-write is and what it is used for. The term is mentioned several times in the Sun JDK tutorials.

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 (re...

I am writing some little script that assembles backup data into one directory. The directory content will then be uploaded to a cloud service and after that we can remove it. I was wondering how on...

It had been my understanding that copy-on-write is not a viable way to implement a conforming std::string in C++11, but when it came up in discussion recently I found myself unable to directly supp...

I want to use SmallVec with Cow. I tried this: use smallvec::SmallVec; use std::borrow::Cow; fn main() { let s = "hello world".to_owned(); let mut s = Cow::Borrowed(s.as_bytes()); clear_subsli...

Say we have a certain parent process with some arbitrary amount of data stored in memory and we use fork to spawn a child process. I understand that in order for the OS to perform copy on write, th...

I have 3 processes communicating over named pipes: server, writer, reader. The basic idea is that the writer can store huge (~GB) binary blobs on the server, and the reader(s) can retrieve it. But ...

I'm trying to share objects between the parent and child process in Python. To play around with the idea, I've created a simple Python script: from multiprocessing import Process from os import ge...

str::to_ascii_lowercase returns a String. Why doesn't it return a Cow<str> just like to_string_lossy or String::from_utf8_lossy? The same applies to str::to_ascii_uppercase.

When we malloc memory, only virtual memory is available, and it actually pointed to zero-page. The real physical memory will be allocated when we try to write to the malloced memory, at this moment...

I have a directory containing source code, which I compile to produce object files. I want to quickly apply a patch and rebuild in such a way that I have simultaneous access to both the old and new...

As the title said, I tried to prove myself that COW(copy on write) is supported for String in Swift. But I cannot find a proof. I proved the COW on Array and Dictionary after trying the following c...

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...

I am trying to create a QList of a polymorphic type that still uses Qt's implicit sharing. My specific use case is passing items held in a QList to QtConcurrent::mapped. The items all descend fro...

I have a very large structure, which I want to ensure is not copied needlessly. How can I make a copy-on-write container for it?

I am trying to understand this dirty CoW proof of concept: https://github.com/dirtycow/dirtycow...ter/dirtyc0w.c. What happens when a child thread (procselfmemThread in the link above) writes to m...

I want to have the advantage of functional data structures (multiple versions of data that can share structure) but be able to modify it in an imperative style. What I'm thinking about (and a pos...