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June 12th 2003
Computer Laboratory > Research > Systems Research Group > NetOS > Seminars > June 12th 2003

Concurrent programming for dummies (and smart people too)


Language support for lightweight transactions

Tim Harris

Concurrent programming is notoriously difficult. Current abstractions are intricate to use and make it hard to design computer systems that are reliable and scalable. We argue in favour of a practical declarative style of concurrency control in which programmers directly indicate the safety properties that they require. In essence, the programmer demarks sections of code which execute within lightweight software-based transactions which commit atomically and exactly once.

These transactions can update shared data, instantiate objects, invoke library features and so on. They can also block, waiting for arbitrary boolean conditions to become true. These features support general-purpose shared data structures such as hashtables, queues and buffers. In general, no performance penalty is incurred for memory accesses outside transactions. Furthermore, transactions which do not access the same shared memory locations can commit concurrently.

In this talk, and the accompanying paper, I will present a design of this proposal along with an implementation and evaluation. This aims (i) to be easier for mainstream programmers to use, (ii) to prevent lock-based priority-inversion and deadlock problems and (iii) to offer good performance and scalability that is at least as good as lock-based schemes.