Speculative Lock Management to Increase Concurrency in Mobile Environments
Since mobile transactions are long-lived, in case of a conflict, the waiting transactions are either blocked for longer durations or aborted if two-phase locking is employed for concurrency control. In this paper, we propose mobile speculative locking (MSL) protocol to reduce the blocking of transactions. MSL allows a transaction to release a lock on a data object whenever it produces corresponding after-image value. By accessing both before- and after-images, the waiting transaction carries out speculative executions at the mobile host. Before the end of commit processing, the transaction that has carried out speculative executions retains appropriate execution based on the termination decisions of preceding transactions. The MSL approach requires extra resources at the mobile host to carry out speculative executions. Since mobile host is operated by single user, we assume that it can support a reasonable number of speculative executions. Through analysis it has been shown that MSL increases concurrency with limited resources available at mobile host.
KeywordsData Object Mobile Host Mobile Environment Concurrency Control Object Server
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