I recommend An Introduction to Parallel Programming by Pacheco. It’s clearly written, and a good intro to parallel programming. If you don’t care about something being tied to a language, then Java Concurrency in Practice is a great resource. Oracle’s online tutorial is free, but probably a bit more succinct than what you’re looking for. … Read more
Note that one interesting aspect of using struct{} for the type pushed to a channel (as opposed to int or bool), is that the size of an empty struct is… 0! See the recent article “The empty struct” (March 2014) by Dave Cheney. You can create as many struct{} as you want (struct{}{}) to push … Read more
They’ll run at the same time. The standard practice around this is to create a file lock (commonly referred to as a flock), and if the lock isn’t available, don’t run. The advantages to this over Zdenek’s approach is that it doesn’t require a database, and when the process ends, the flock is automatically released. … Read more
I think they are sometimes used interchangeably, and if the transaction only involves one object then they are essentially the same, but MVCC is an extension of optimistic concurrency (or a version of it) that provides guarantees when more than one object is involved. Say that you have two objects, A and B, which must … Read more
In the Intel® 64 and IA-32 Architectures Developer’s Manual: Vol. 3A, which nowadays contains the specifications of the memory ordering white paper you mention, it is said in section 8.1.1 that: The Intel486 processor (and newer processors since) guarantees that the following basic memory operations will always be carried out atomically: Reading or writing a … Read more
Actor Model I heard of message passing where there is no memory shared. Is it about Erlang-style Actors? Scala uses this idea in its Actors framework (thus, in Scala its not a part of the language, just a library) and it looks quite sexy! In a few words Actors are objects that have no shared … Read more
Why you should limit queuing Any requests that aren’t immediately handled by an application process, are queued. Queuing is usually is bad: it often means that your server cannot handle the requests quickly enough. A larger queue means that requests are less likely to be dropped. But this comes with a drawback: during busy times, … Read more
It seems like part what you’re really asking is: Why isn’t the lock prefix implicit for cmpxchg with a memory operand, like it is for xchg (since 386)? The simple answer (that others have given) is simply that Intel designed it this way. But this leads to the question: Why did Intel do that? Is … Read more
In the simple case given, unlocking in the reverse order is not necessary to avoid a deadlock. However, as the code gets more complicated, unlocking in the reverse order helps you maintain proper lock ordering. Consider: A.lock(); B.lock(); Foo(); A.unlock(); Bar(); B.unlock(); If Bar() attempts to reacquire A, you’ve effectively broken your lock ordering. You’re … Read more