Note: As of Go 1.5, GOMAXPROCS is set to the number of cores of the hardware: golang.org/doc/go1.5#runtime, below the original answer before 1.5. When you run Go program without specifying GOMAXPROCS environment variable, Go goroutines are scheduled for execution in single OS thread. However, to make program appear to be multithreaded (that’s what goroutines are … Read more
GetOrAdd won’t become an asynchronous operation because accessing the value of a dictionary isn’t a long running operation. What you can do however is simply store tasks in the dictionary, rather than the materialized result. Anyone needing the results can then await that task. However, you also need to ensure that the operation is only … Read more
Since this question was asked in 2010, there has been real simplification in how to do simple multithreading with Python with map and pool. The code below comes from an article/blog post that you should definitely check out (no affiliation) – Parallelism in one line: A Better Model for Day to Day Threading Tasks. I’ll … Read more
OK, so there are 3 types of methods in CompletableFuture. For example: thenApply() thenApplyAsync(Function) (without an Executor) thenApplyAsync(Function, Executor) (with an Executor) The last one means that this action will execute in the Executor that you pass to it and it is the most obvious one. The second one means that the action is executed … Read more
You’re calling wait and notify without synchronizing on the thing you’re waiting on or notifying. As documented in Object.notifyAll: Throws: IllegalMonitorStateException – if the current thread is not the owner of this object’s monitor. So this: synchronized(nameSetLock){ notifyAll(); } should be: synchronized(nameSetLock){ nameSetLock.notifyAll(); } … and ditto for wait. Note that your current code wouldn’t … Read more
It is not new question when SQL Server may slowdown queries because of Parameter Sniffing. Problem can be solved by converting parameters to constants or by adding OPTION(RECOMPILE) to the end of the query. This answer adds DbCommandInterceptor to DbContextOptions and appends OPTION(RECOMPILE) hint to particular queries. Configuring DbContext builder.UseSqlServer(connectionString) .UseRecompileExtensions(); // registering interceptor How … Read more
Returning null is not the issue. The issue is that the new instance may be in a partially constructed state as perceived by another thread. Consider this declaration of Foo. class Foo { public int variable1; public int variable2; public Foo() { variable1 = 1; variable2 = 2; } } Here is how the code … Read more
The use case is the first successful completion: scala> :pa // Entering paste mode (ctrl-D to finish) def firstSuccessOf[T](fs: Future[T]*)(implicit x: ExecutionContext): Future[T] = { val p = Promise[T]() val count = new java.util.concurrent.atomic.AtomicInteger(fs.size) def bad() = if (count.decrementAndGet == 0) { p tryComplete new Failure(new RuntimeException(“All bad”)) } val completeFirst: Try[T] => Unit = … Read more
I don’t believe the text you cites implies anything of the sort. It doesn’t even mention read() or write() or POSIX. In fact, read() and write() cannot be relied on to be atomic. The only thing POSIX says is that write() must be atomic if the size of the write is less than PIPE_BUF bytes, … Read more
The issue is that you’re executing that as a standalone program, whose main thread is terminating before one of the worker threads can execute the “Hello future!” println. (The threads that the new futures library spawns are daemon threads). You can also use the Await object (also in scala.concurrent) to wait until the future f … Read more