This paper presents a static race detection analysis for multithreaded Java programs. Our analysis is based on a formal type system that is capable of capturing many common synchronization patterns. These patterns include classes with internal synchronization, classes that require client-side synchronization, and thread-local classes. Experience checking over 40,000 lines of Java code with the type system demonstrates that it is an effective approach for eliminating races conditions. On large examples, fewer than 20 additional type annotations per 1000 lines of code were required by the type checker, and we found a number of races in the standard Java libraries and other test programs. 1

Containment of objects is a natural concept that has been poorly supported in object-oriented programming languages. For a predefined set of ownership contexts, this paper presents a type system that enforces certain containment relationships for run-time objects. A fixed ordering relationship is presumed between the owners. The formalisation of ownership types has developed from our work with flexible alias protection together with an investigation of structural properties of object graphs based on dominator trees. Our general ownership type system permits fresh ownership contexts to be created at run-time. Here we present a simplified system in which the ownership contexts are predefined. This is powerful enough to express and enforce constraints about a system's high-level structure. Our formal system is presented in an imperative variant of the object calculus. We present type preservation and soundness results. Furthermore we highlight how these type theoretic results establish a containment invariant for objects, in which access to contained objects is only permitted via their owners. In effect, the predefined ownership ordering restricts the permissible inter-object reference structure.

Making software reliable is one of the most important technological challenges facing our society today. This thesis presents a new type system that addresses this problem by statically preventing several important classes of programming errors. If a program type checks, we guarantee at compile time that the program does not contain any of those errors. We designed our type system in the context of a Java-like object-oriented language; we call the resulting system SafeJava. The SafeJava type system offers significant software engineering benefits. Specifically, it provides a statically enforceable way of specifying object encapsulation and enables local reasoning about program correctness; it combines effects clauses with encapsulation to enable modular checking of methods in the presence of subtyping; it statically prevents data races and deadlocks in multithreaded programs, which are known to be some of the most difficult programming errors to detect, reproduce, and

Distributed software problems are often addressed with object-oriented solutions. Objects provide the benefits of encapsulation and abstraction that have proven useful in managing the complexity of sequential code. However, the management of distributed objects is typically by means of complex APIs, such as CORBA, DCOM, or Java RMI. The complexity of the APIs is itself a hurdle to the writing of efficient, robust programs. An alternate approach is to provide the programmer with a simple interface to an underlying object management layer that provides efficient access to objects and sufficient power for common distributed programming tasks. This paper describes the implementation of the Kan system. It has a clear, simple object model with powerful semantics, embodying such concepts as atomic transactions, asynchronous method calls, and multithreading. The model primitives help the programmer avoid common concurrent programming errors, allowing clean expressions of concurrent a...

Programmers have come to expect better integration between databases and the programming languages they use. While this trend continues unabated, database concurrency scheduling has remained blind to the programs. We propose that the database client programs provide a large untapped information resource for increasing database throughput.

We present a memory management scheme for Java based on thread-local heaps. Assuming most objects are created and used by a single thread, it is desirable to free the memory manager from redundant synchronization for thread-local objects. Therefore, in our scheme each thread receives a partition of the heap in which it allocates its objects and in which it does local garbage collection without synchronization with other threads. We dynamically monitor to determine which objects are local and which are global. Furthermore, we suggest using profiling to identify allocation sites that almost exclusively allocate global objects, and allocate objects at these sites directly in a global area.

The main loop of modular points-to analysis typically consists of two major phases. The first, a bottom-up process, transforms each procedure into a self-contained module that encapsulates all the internal dataflow along with side e#ects from procedure calls. The second, a top-down process, provides the input points-to information to each procedure and computes the actual points-to information. We propose

Remote Method Invocation (RMI), a mechanism to access remote objects in Java-based distributed applications, uses network communication for each method invocation. Consequently, using RMI in a wide-area environment can cause poor application performance. One solution to improve performance is to cache the objects such that network communication is not necessary for each method invocation. In this paper, we present mechanisms to transparently add object caching to RMI. These mechanisms are compatible with existing RMI applications and use an event-based model to support different consistency policies. The mechanisms also include the ability to adaptively select the consistency policy for an object based on its usage pattern. A novel feature of our mechanisms is the use of a ‘reduced object’, which is a partial representation of the RMI object. We experimentally evaluate and demonstrate the benefits of our

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