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Performance optimization strategies of last resort [closed]

...y under a broad range of scenarios, and perform null checks on parameters, etc. By re-implementing a method you may be able to strip out a lot of logic that does not apply in the exact circumstance you are using it. Down-sides: writing additional code means more surface area for bugs. Do use library...
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Why is reading lines from stdin much slower in C++ than Python?

...lly timing the execution of cat, not your benchmark. The 'user' and 'sys' CPU usage displayed by time are those of cat, not your benchmarked program. Even worse, the 'real' time is also not necessarily accurate. Depending on the implementation of cat and of pipelines in your local OS, it is possib...
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How to manually expand a special variable (ex: ~ tilde) in bash

...${username#"~"} IFS=: read -r _ _ _ _ _ homedir _ < <(getent passwd "$username") if [[ $path = */* ]]; then path=${homedir}/${path#*/} else path=$homedir fi ;; esac resultPathElements+=( "$path" ) done local result print...
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How to Calculate Execution Time of a Code Snippet in C++

... I have another working example that uses microseconds (UNIX, POSIX, etc). #include <sys/time.h> typedef unsigned long long timestamp_t; static timestamp_t get_timestamp () { struct timeval now; gettimeofday (&now, NULL); return now.tv_usec + ...
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Is SHA-1 secure for password storage?

... systems do: the hashed passwords, which used to be in the world-readable /etc/password file, are now in the /etc/shadow file which is protected against read access, except by a few privileged applications. The assumption here is that if the attacker can read /etc/shadow, then he probably has enough...
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What is “vectorization”?

...GE Vectorization describes the absence of any explicit looping, indexing, etc., in the code - these things are taking place, of course, just “behind the scenes” in optimized, pre-compiled C code. Vectorized code has many advantages, among which are: vectorized code is more concise and easier ...
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How do I get Windows to go as fast as Linux for compiling C++?

...is by looking at the differences between the two compilers, build systems, etc etc. – surfasb Dec 20 '11 at 1:24 Windo...
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从网购到火车票,对比淘宝12306网为何如此烂? - 大数据 & AI - 清泛网 - ...

...到让人“一票难求”的订票网站-12306。12306网站购票难的问题几乎成了所有人的共识。来自前支付宝架构师冯大辉(@Fenng)的这条微博翻出12306这笔账,别有一番滋味。 以冯大辉的计算方法,支付宝11月11日一天就处理了1亿零580万...
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What are the file limits in Git (number and size)?

... if they are called frequently by the web front-end to GitLab/Stash/GitHub etc then they can become bottlenecks. (e.g. 'git branch --contains' seems terribly adversely affected by large numbers of branches.) git-blame could be slow when a file is modified a lot. ...
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“An attempt was made to load a program with an incorrect format” even when the platforms are the sam

...been unchecked for my executable, so it was still running with the old Any CPU build. After I fixed that, Visual Studio complained that it couldn't debug the assembly, but that was fixed with a restart. share | ...