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What data type to use for hashed password field and what length?

...le numerical value, others have more parameters there (for example to tune CPU usage and RAM usage separately). The salt. Since the salt must be globally unique, it has to be stored for each account. The salt should be generated randomly on each password change. The hash proper, i.e. the output of t...
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Why does changing 0.1f to 0 slow down performance by 10x?

... sets FTZ (flush to zero) and DAZ (denormal are zero) in the MXCSR, so the CPU never has to take a slow microcode assist for denormals. – Peter Cordes Jan 16 '19 at 10:23 add ...
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Evaluating a mathematical expression in a string

...rbitrary commands eval("9**9**9**9**9**9**9**9", {'__builtins__': None}) # CPU, memory Note: even if you use set __builtins__ to None it still might be possible to break out using introspection: eval('(1).__class__.__bases__[0].__subclasses__()', {'__builtins__': None}) Evaluate arithmetic expr...
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How to append rows to an R data frame

...t(r) For 1E5 rows (measurements done on Intel(R) Core(TM) i7-4710HQ CPU @ 2.50GHz): nr function time 4 data.frame 228.251 3 sqlite 133.716 2 data.table 3.059 1 rbindlist 169.998 0 placebo 0.202 It looks like the SQLite-based sulution, although r...
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How can bcrypt have built-in salts?

...ext. What is more important : There is no hashing in this process, rather CPU expensive encryption - decryption. thus rainbow tables are less relevant here. share | improve this answer | ...
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How much faster is C++ than C#?

...ter will be competing with your code for instruction and data cache in the CPU. We know that cache dominates when it comes to performance and native languages like C++ do not have this type of contention, by definition. a run-time optimizer's time budget is necessarily much more constrained than th...
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Android destroying activities, killing processes

... persistent data, stop animations and other things that may be consuming CPU, etc. Implementations of this method must be very quick because the next activity will not be resumed until this method returns. Followed by either onResume() if the activity returns back to the front, or onStop() i...
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凤姐当天使 徐小平胡海泉薛蛮子王刚怎么看? - 资讯 - 清泛网 - 专注C/C++...

...们投资偏硬技术比较多一点,一般现在的天使碰不到这些问题,你要投硬技术的时候,其实是特别痛苦的一件事,比如说现在天使投资都说人不好,我们就不投了,投硬技术,往往真理就在这个人的手里,他能掌握这个核心技术...
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内存优化总结:ptmalloc、tcmalloc和jemalloc - 操作系统(内核) - 清泛网 - ...

...内存到CentralCache里。 解决了ptmalloc2中arena之间不能迁移的问题。 Tcmalloc占用更少的额外空间。例如,分配N个8字节对象可能要使用大约8N * 1.01字节的空间。即,多用百分之一的空间。Ptmalloc2使用最少8字节描述一个chunk。 更快。...
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OS detecting makefile

...commended or ideal; they're just what the project to which I was adding OS/CPU auto-detection happened to be using. ifeq ($(OS),Windows_NT) CCFLAGS += -D WIN32 ifeq ($(PROCESSOR_ARCHITEW6432),AMD64) CCFLAGS += -D AMD64 else ifeq ($(PROCESSOR_ARCHITECTURE),AMD64) ...