Single Lock Research Articles

Detection of deadlock potentials in multithreaded programs

Concurrent programs are well known for containing errors that are difficult to detect, reproduce, and diagnose. Deadlock is a common concurrency error, which occurs when a set of threads are blocked, due to each attempting to acquire a lock held by another. This paper presents a collection of highly scalable static and dynamic techniques for exposing potential deadlocks. The basis is a known algorithm, which, when locks are acquired in a nested fashion, captures the nesting order in a lock graph. A cycle in the graph indicates a deadlock potential. We propose three extensions to this basic algorithm to eliminate, or label as low severity, false warnings of possible deadlocks (false positives). These false positives may be due to cycles within one thread, cycles guarded by a gate lock (an enclosing lock that prevents deadlocks), and cycles involving several code fragments that cannot possibly execute in parallel. We also present a technique that combines information from multiple runs of the program into a single lock graph, to find deadlock potentials that would not be revealed by analyzing one run at a time. Finally, this paper describes the use of static analysis to automatically reduce the overhead of dynamic checking for deadlock potentials.

Differential 14-3-3 Affinity Capture Reveals New Downstream Targets of Phosphatidylinositol 3-Kinase Signaling

We devised a strategy of 14-3-3 affinity capture and release, isotope differential (d0/d4) dimethyl labeling of tryptic digests, and phosphopeptide characterization to identify novel targets of insulin/IGF1/phosphatidylinositol 3-kinase signaling. Notably four known insulin-regulated proteins (PFK-2, PRAS40, AS160, and MYO1C) had high d0/d4 values meaning that they were more highly represented among 14-3-3-binding proteins from insulin-stimulated than unstimulated cells. Among novel candidates, insulin receptor substrate 2, the proapoptotic CCDC6, E3 ubiquitin ligase ZNRF2, and signaling adapter SASH1 were confirmed to bind to 14-3-3s in response to IGF1/phosphatidylinositol 3-kinase signaling. Insulin receptor substrate 2, ZNRF2, and SASH1 were also regulated by phorbol ester via p90RSK, whereas CCDC6 and PRAS40 were not. In contrast, the actin-associated protein vasodilator-stimulated phosphoprotein and lipolysis-stimulated lipoprotein receptor, which had low d0/d4 scores, bound 14-3-3s irrespective of IGF1 and phorbol ester. Phosphorylated Ser19 of ZNRF2 (RTRAYpS19GS), phospho-Ser90 of SASH1 (RKRRVpS90QD), and phospho- Ser493 of lipolysis-stimulated lipoprotein receptor (RPRARpS493LD) provide one of the 14-3-3-binding sites on each of these proteins. Differential 14-3-3 capture provides a powerful approach to defining downstream regulatory mechanisms for specific signaling pathways.

Single global lock semantics in a weakly atomic STM

As memory transactions have been proposed as a language-level replacement for locks, there is growing need for well-defined semantics. In contrast to database transactions, transaction memory (TM) semantics are complicated by the fact that programs may access the same memory locations both inside and outside transactions. Strongly atomic semantics, where non-transactional accesses are treated as implicit single-operation transactions, remain difficult to provide without specialized hardware support and/or significant performance overhead. As an alternative, many in the community have informally proposed that a single global lock semantics [16, 9], where transaction semantics are mapped to those of regions protected by a single global lock, provide an intuitive and efficiently implementable model for programmers. In this paper, we explore the implementation and performance implications of single global lock semantics in a weakly atomic STM from the perspective of Java, and we discuss why even recent STM implementations fall short of these semantics. We describe a new weakly atomic Java STM implementation that provides single global lock semantics while permitting concurrent execution, but we show that this comes at a significant performance cost. We also propose and implement various alternative semantics that loosen single lock requirements while still providing strong guarantees. We compare our new implementations to previous ones, including a strongly atomic STM. [22]

Access privilege management in protection systems

We consider the problem of managing access privileges on protected objects. We associate one or more locks with each object, one lock for each access right defined by the object type. Possession of an access right on a given object is certified by possession of a key for this object, if this key matches one of the object locks. We introduce a number of variants to this basic key–lock technique. Polymorphic access rights make it possible to decrease the number of keys required to certify possession of complex access privileges that are defined in terms of several access rights. Multiple locks on the same access right allow us to exercise forms of selective revocation of access privileges. A lock conversion function can be used to reduce the number of locks associated with any given object to a single lock. The extent of the results obtained is evaluated in relation to alternative methodologies for access privilege management.

Accurate mass determination of a metabolite of a potential diagnostic imaging drug candidate by high performance liquid chromatography with time-of-flight mass spectrometry.

A potential drug candidate containing a multiplicity of sulphur atoms, and one unknown in vivo main metabolite, were analysed with an high performance liquid chromatograph time-of-flight mass spectrometer (LC/TOF-MS). Sensitivity and resolution were compared with those obtained with a quadrupole instrument. The LC/TOF-MS provided a more than 200-fold advantage in sensitivity, higher resolving power for the isotopic envelopes of the molecular ions produced by electrospray, and simple procedures for the determination of elemental composition. The exact masses of the candidate and its main metabolite were determined to within 1.5 to 3 ppm, using a single lock mass correction.

Thermal investigations on yellow wools

Thermal investigations (TG, DTG) were carried out on the wool of Polish Mountain, Polish Lowland, Polish Merino and Polish Long-fleeced sheep in order to find dependences between the yellowing of the wool fibres and their structure. The thermal investigations were made on a single lock, taking into account the upper (yellow) and the lower (white) parts of the staple.

Perfornance Study of Two Phase Locking in Single-Site Database Systems

Many database systems guarantee the consistency of the database for concurrent transaction processing by a standard locking protocol called two phase locking. The performance of such systems is dependent on various factors, among which are the choices of locking granularity (the amount of data controlled by a single lock) and degree of multiprogramming (the maximum number of transactions allowed to run concurrently in the system). Previous simulation and experimental studies on such systems suggest that the choices are dependent on the properties of the application.

Felting and Flocculation of Natural Wool in Water and in Mixed Solvents

Shrinkage-time curves have been determined for untreated wool fabric in various water/dimethylformamide (DMF) and water/ethanol mixtures, using a Cubex machine. Felting shrinkage decreases drastically above 90% DMF and around 85% ethanol. In a qualitative way the shrinkage results correlate well with the decreased attraction between the wool fibers in the mixed solvents, as measured in flocculation tests of the chopped wool fibers. Root-to-tip variation of interfiber attraction for natural wool in water has been examined by the flocculation of parts of wool fibers cut from a single lock of oriented natural wool. The results indicate a decrease in hydrophobicity from fiber root to fiber tip, as expected, from increased oxidation in weathering.

The Value of Single Lock Samples as a Measure of Seed Purity in Cotton1

Agronomy JournalVolume 26, Issue 9 p. 781-785 Article The Value of Single Lock Samples as a Measure of Seed Purity in Cotton1 J. H. Moore, J. H. Moore Cotton Technologist. The author wishes to express his appreciation to Director R. Y. Winters for helpful suggestions in preparing the manuscript.Search for more papers by this author J. H. Moore, J. H. Moore Cotton Technologist. The author wishes to express his appreciation to Director R. Y. Winters for helpful suggestions in preparing the manuscript.Search for more papers by this author First published: 01 September 1934 https://doi.org/10.2134/agronj1934.00021962002600090013x 1 Contribution from the Department of Agronomy, North Carolina Agricultural Experiment Station, Raleigh, N. C. Published with the approval of the Director as Paper No. 81. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume26, Issue9September 1934Pages 781-785 RelatedInformation