Java Quotes

“It is far easier to design a class to be thread-safe than to retrofit it for thread safety later.”
― Brian Goetz, Java Concurrency in Practice

“Sometimes abstraction and encapsulation are at odds with performance — although not nearly as often as many developers believe — but it is always a good practice first to make your code right, and then make it fast.”
― Brian Goetz, Java Concurrency in Practice

“Whenever more than one thread accesses a given state variable, and one of them might write to it, they all must coordinate their access to it using synchronization.”
― Brian Goetz, Java Concurrency in Practice

“When a field is declared volatile, the compiler and runtime are put on notice that this variable is shared and that operations on it should not be reordered with other memory operations. Volatile variables are not cached in registers or in caches where they are hidden from other processors, so a read of a volatile variable always returns the most recent write by any thread.”
― Brian Goetz, Java Concurrency in Practice

“The possibility of incorrect results in the presence of unlucky timing is so important in concurrent programming that it has a name: a race condition. A race condition occurs when the correctness of a computation depends on the relative timing or interleaving of multiple threads by the runtime; in other words, when getting the right answer relies on lucky timing.”
― Brian Goetz, Java Concurrency in Practice

“Compound actions on shared state, such as incrementing a hit counter (read-modify-write) or lazy initialization (check-then-act), must be made atomic to avoid race conditions. Holding a lock for the entire duration of a compound action can make that compound action atomic. However, just wrapping the compound action with a synchronized block is not sufficient; if synchronization is used to coordinate access to a variable, it is needed everywhere that variable is accessed. Further, when using locks to coordinate access to a variable, the same lock must be used wherever that variable is accessed.”
― Brian Goetz, Java Concurrency in Practice

“Debugging tip: For server applications, be sure to always specify the -server JVM command line switch when invoking the JVM, even for development and testing. The server JVM performs more optimization than the client JVM, such as hoisting variables out of a loop that are not modified in the loop; code that might appear to work in the development environment (client JVM) can break in the deployment environment (server JVM).”
― Brian Goetz, Java Concurrency in Practice