Facebook engineers query multiple databases to monitor and analyze Facebook products and services. The fastest of these databases is Scuba, which achieves subsecond query response time by storing all of its data in memory across hundreds of servers. We are continually improving the code for Scuba and would like to push new software releases at least once a week. However, restarting a Scuba machine clears its memory. Recovering all of its data from diskabout 120 GB per machine -takes 2.5-3 hours to read and format the data per machine. Even 10 minutes is a long downtime for the critical applications that rely on Scuba, such as detecting user-facing errors. Restarting only 2% of the servers at a time mitigates the amount of unavailable data, but prolongs the restart duration to about 12 hours, during which users see only partial query results and one engineer needs to monitor the servers carefully. We need a faster, less engineer intensive, solution to enable frequent software upgrades.In this paper, we show that using shared memory provides a simple, effective, fast, solution to upgrading servers. Our key observation is that we can decouple the memory lifetime from the process lifetime. When we shutdown a server for a planned upgrade, we know that the memory state is valid (unlike when a server shuts down unexpectedly). We can therefore use shared memory to preserve memory state from the old server process to the new process. Our solution does not increase the server memory footprint and allows recovery at memory speeds, about 2-3 minutes per server. This solution maximizes uptime and availability, which has led to much faster and more frequent rollouts of new features and improvements. Furthermore, this technique can be applied to the in-memory state of any database, even if the memory contains a cache of a much larger disk-resident data set, as in most databases.
Objective: To estimate the knowledge, prevalence and factors associated with practice of modern contraceptive methodsamong currently married males of reproductive age group (20-49years) in soldier bazaar Karachi Pakistan. Period and Setting: The study wascarried out in Karachi in 2010 in area of soldier bazaar. Methods: In person interviews were carried out with150 males (Aged 20-49) fromdifferent areas of Soldier Bazaar which were taken randomly. Data was collected regarding socio-demographic features, reproductive profile,family size, knowledge, and practices of family planning services and reasons for non-use of contraception. Results: The half of respondentshas knowledge about condom (52%), IUCD (44.6%), Oral pills (43.7%), injection (41.3%) and tubal ligation (32.6%). Knowledge aboutwithdrawal and male sterilization (vasectomy) which are male contraceptive methods is low. Only 19.3% respondents know about all themethods and another 9.3% do not know about any method.32% respondents showed willingness to undergo vasectomy as compared to 68%who are not willing for the procedure.8% of the respondents use some of family planning methods 30% of respondents (and their wives) did notuse any contraceptive method because they want more children. Surprisingly 3.5% respondents among non-users did not know about thefamily planning methods. Educational level has shown direct relationship with knowledge and practice of family planning. Conclusions:Prevalence of male contraceptive methods along with knowledge of other methods is found very low and has direct relation with attitude andpractice of family planning, not only among themselves but also on the adoption of contraceptive measures of their wives.
Objectives:This study was designed to find the reliability of serum NGAL as an early and better diagnostic biomarker than that of serum creatinine for acute kidney injury after percutaneous coronary intervention in Pakistani population.Materials and methods:One hundred and fifty-one patients undergoing elective percutaneous coronary intervention were included and demographic data were recorded. Blood was drawn by venipuncture in clot activator vacutainers and serum was separated and stored at 4°C. Sample was drawn before the percutaneous procedure and subsequently sampling was done serially for 5 days.Results:The mean±SD serum NGAL pre-PCI (39.92± 10.35 μg/L) and 4 h post-PCI (100.42±26.07 μg/L) showed highly significant difference (p<0.001). The mean±SD serum creatinine pre-PCI (70.1±11.8 μmol/L) and post-PCI (71.2±11.6 μmol/L) showed significant difference (p=0.005) on day 2 onwards but mean microalbumin showed insignificant results (p=0.533). The serum NGAL predicted CI-AKI with sensitivity of 95.8% and specificity of 97.6% for a cut off value of 118 μg/L.Conclusion:Our results suggest that NGAL is an excellent early diagnostic biomarker for acute kidney injury in patients undergoing elective percutaneous coronary intervention.
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