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. We have developed and implemented techniques that double the performance of dynamically-typed object-oriented languages. Our SELF implementation runs twice as fast as the fastest Smalltalk implementation, despite SELF's lack of classes and explicit variables. To compensate for the absence of classes, our system uses implementation-level maps to transparently group objects cloned from the same prototype, providing data type information and eliminating the apparent space overhead for prototype-based systems. To compensate for dynamic typing, user-defined control structures, and the lack of explicit variables, our system dynamically compiles multiple versions of a source method, each customized according to its receiver's map. Within each version the type of the receiver is fixed, and thus the compiler can statically bind and inline all messages sent to self. Message splitting and type prediction extract and preserve even more static type information, allowing the compiler to inline ma...

Object-oriented programming languages promise to improve programmer productivity by supporting abstract data types, inheritance, and message passing directly within the language. Unfortunately, traditional implementations of object-oriented language features, particularly message passing, have been much slower than traditional implementations of their non-object-oriented counterparts: the fastest existing implementation of Smalltalk-80 runs at only a tenth the speed of an optimizing C implementation. The dearth of suitable implementation technology has forced most object-oriented languages to be designed as hybrids with traditional non-object-oriented languages, complicating the languages and making programs harder to extend and reuse. This dissertation describes a collection of implementation techniques that can improve the run-time performance of object-oriented languages, in hopes of reducing the need for hybrid languages and encouraging wider spread of purely object-oriented langu...

. Current data abstraction mechanisms are not adequate to control sharing of state in the general case involving objects in linked structures. The pervading possibility of sharing is a source of errors and an obstacle to language implementation techniques. We present a general extension to programming languages which makes the ability to share state a first class property of a data type, resolving a long-standing flaw in existing data abstraction mechanisms. Balloon types enforce a strong form of encapsulation: no state reachable (directly or transitively) by a balloon object is referenced by any external object. Syntactic simplicity is achieved by relying on a non-trivial static analysis as the checking mechanism. Balloon types are applicable in a wide range of areas such as program transformation, memory management and distributed systems. They are the key to obtaining self-contained composite objects, truly opaque data abstractions and value types---important concepts for the develo...

Abstract not found

Abstract. We have developed and implemented techniques that double the performance of dynamically-typed object-oriented languages. Our SELF implementation runs twice as fast as the fastest Smalltalk implementation, despite SELF’s lack of classes and explicit variables. To compensate for the absence of classes, our system uses implementation-level maps to transparently group objects cloned from the same prototype, providing data type information and eliminating the apparent space overhead for prototype-based systems. To compensate for dynamic typing, user-defined control structures, and the lack of explicit variables, our system dynamically compiles multiple versions of a source method, each customized according to its receiver’s map. Within each version the type of the receiver is fixed, and thus the compiler can statically bind and inline all messages sent to self. Message splitting and type prediction extract and preserve even more static type information, allowing the compiler to inline many other messages. Inlining dramatically improves performance and eliminates the need to hard-wire low-level methods such as +, ==, and ifTrue:. Despite inlining and other optimizations, our system still supports interactive programming environments. The system traverses internal dependency lists to invalidate all compiled methods

This dissertation shows that operating systems can provide fundamental services an order of magnitude more efficiently than traditional implementations. It describes the implementation of a new operating system kernel, Synthesis, that achieves this level of performance. The Synthesis kernel combines several new techniques to provide high performance without sacrificing the expressive power or security of the system. The new ideas include: ffl Run-time code synthesis --- a systematic way of creating executable machine code at runtime to optimize frequently-used kernel routines --- queues, buffers, context switchers, interrupt handlers, and system call dispatchers --- for specific situations, greatly reducing their execution time. ffl Fine-grain scheduling --- a new process-scheduling technique based on the idea of feedback that performs frequent scheduling actions and policy adjustments (at submillisecond intervals) resulting in an adaptive, self-tuning system that can support real-ti...

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Abstract A multidatabase system (MDBS) is a confederation of pre-existing distributed, heterogeneous, and autonomous database systems. There has been a recent proliferation of research suggesting the application of object-oriented techniques to facilitate the complex task of designing and implementing MDBSs. Although this approach seems promising, the lack of a general framework impedes any further development. The goal of this paper is to provide a concrete analysis and categorization of the various ways in which object orientation has affected the task of designing and implementing MDBSs.

Modernsoft aresystE0 are increasingly requiredt be open and dist ibut81 Suchsyst08 are opennot only int erms ofnet orkconnectR06 andint0 operabilit support forhet1 ogeneous hardware andsoft are plat orms,but above all, int2 ms of evolving and changingrequirement . Alt169, object,7 ient3 t331,7E8 offers some relief,t o a largeext27 t he languages,met2R8 andtd,2 fail t addresstd needs of opensystE3 becausetc y donot escape from tadit192, models of soft are development tpm assume syst, requirement t be closed and st ble.We argue te, open systE8 requirement can only beadequat7E addressed byadopt9, a component,t ient0 as opposedt a purelyobject3E ient2 soft are development approach, byshift7, emphasis away from programming and t wards generalizedsoft arecomposit739 1.1 IntrotrWk5k There has been ac8P8("NP( trend in the development of softwareapplic("NP( away from crom"5 proprietary systems towardsso-c)55( open systems. This trendce be largely attributed to the rapid advancE inc")PPFE hardware tec)F5E"N that have vastlyincy"H5F the cAAF("N)5jjF power available to end-userapplic"P(HHj With new possibilitiescos new needs: in order to survive,c"))AAF" ve businesses must be able to effec) vely exploit newtecP"N)P( as itbecj() available, so existingapplicP)Pjj must be able to work with new, independently developed systems. Wec) see, then, that open systems must be "open" in at least three important ways [49]: 1. Topology: openapplic)E"NE run onc)jEH("NEj networks. 2. PlatF'"A the hardware and software platforms are heterogeneous. 3. EvolutAD' requirements are unstable andc"P(AA)"N ccP(A *In ObjectADL/F/"t Softct CompositL/ , O. Nierstrasz and D. Tsic5A"NE) (Ed.),Prentic Hall, 1995, pp. 3-28. For more information, please see:http://iamw3(0(0(0(0(w157(158(159 4 Componen...