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How do cache lines work?
...eval process can take ~90 nanoseconds, or ~250 clock cycles (from the CPU knowing the address to the CPU receiving data).
By contrast, a hit in L1 cache has a load-use latency of 3 or 4 cycles, and a store-reload has a store-forwarding latency of 4 or 5 cycles on modern x86 CPUs. Things are simila...
Disable ONLY_FULL_GROUP_BY
...b is included within this my.cnf file, in 16.04 at least (configuration is now split up into multiple files).
– jwinn
Dec 30 '16 at 4:52
2
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Parse a .py file, read the AST, modify it, then write back the modified source code
...asy, without writing new .py files! If you expand your question to let us know what you actually want to accomplish, new .py files will probably not be involved in the answer at all; I have seen hundreds of Python projects doing hundreds of real-world things, and not a single one of them needed to e...
Why does ReSharper tell me “implicitly captured closure”?
...n a little astonished to find the rules were different here. The more you know, I guess.
– dlf
Mar 3 '16 at 20:06
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Filter rows which contain a certain string
...
option 1 is to know for sure that dplyr loaded last. option 2 is you prefix dplyr::filter.
– userJT
Mar 1 '16 at 14:30
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Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?
...on is [A] rather than [+A]).
Note that there is another type of variance known as contravariance. This is very important as it explains why covariance can cause some issues. Contravariance is literally the opposite of covariance: parameters vary upward with subtyping. It is a lot less common par...
Is multiplication and division using shift operators in C actually faster?
...wer: Not likely.
Long answer:
Your compiler has an optimizer in it that knows how to multiply as quickly as your target processor architecture is capable. Your best bet is to tell the compiler your intent clearly (i.e. i*2 rather than i << 1) and let it decide what the fastest assembly/mach...
Difference between String replace() and replaceAll()
...erloaded to accept both a primitive char and a CharSequence as arguments.
Now as far as the performance is concerned, the replace() method is a bit faster than replaceAll() because the latter first compiles the regex pattern and then matches before finally replacing whereas the former simply matche...
Why should the Gradle Wrapper be committed to VCS?
...per is to be able, without having ever installed gradle, and without even knowing how it works, where to download it from, which version, to clone the project from the VCS, to execute the gradlew script it contains, and to build the project without any additional step.
If all you had was a gradle v...
Why use apparently meaningless do-while and if-else statements in macros?
...say you
had something like your second macro.
#define BAR(X) f(x); g(x)
Now if you were to use BAR(X); in an if ... else statement, where the bodies of the if statement were not wrapped in curly brackets, you'd get a bad surprise.
if (corge)
BAR(corge);
else
gralt();
The above code would e...