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How efficient is locking an unlocked mutex? What is the cost of a mutex?
...bunch of mutexes or a single one for an object.
If you have many threads and the access to the object happens often, then multiple locks would increase parallelism. At the cost of maintainability, since more locking means more debugging of the locking.
How efficient is it to lock a mutex? I.e....
Capitalize first letter. MySQL
...o WOrLd, BLABLA to BLABLA, etc. If you want to upper-case the first letter and lower-case the other, you just have to use LCASE function :
UPDATE tb_Company
SET CompanyIndustry = CONCAT(UCASE(LEFT(CompanyIndustry, 1)),
LCASE(SUBSTRING(CompanyIndustry, 2)));
Note that...
How do I write a correct micro-benchmark in Java?
How do you write (and run) a correct micro-benchmark in Java?
11 Answers
11
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Passing arrays as url parameter
...am%5B1%5D=4&aParam%5Ba%5D=b&aParam%5Bc%5D=d"
http_build_query() handles all the necessary escaping for you (%5B => [ and %5D => ]), so this string is equal to aParam[0]=1&aParam[1]=4&aParam[a]=b&aParam[c]=d.
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Finding ALL duplicate rows, including “elements with smaller subscripts”
...me is a duplicate of an element with a smaller subscript. So if rows 3, 4, and 5 of a 5-row data frame are the same, duplicated will give me the vector
...
Windows batch files: .bat vs .cmd?
As I understand it, .bat is the old 16-bit naming convention, and .cmd is for 32-bit Windows, i.e., starting with NT. But I continue to see .bat files everywhere, and they seem to work exactly the same using either suffix. Assuming that my code will never need to run on anything older than NT, d...
INSTALL_FAILED_NO_MATCHING_ABIS when install apk
I tried to install my app into Android L Preview Intel Atom Virtual Device, it failed with error:
24 Answers
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How to read data From *.CSV file using javascript?
...e escaped quotes. I'm leaving my answer for those who want something quick and dirty, but I recommend Evan's answer for accuracy.
This code will work when your data.txt file is one long string of comma-separated entries, with no newlines:
data.txt:
heading1,heading2,heading3,heading4,heading5,...
MySQL - Get row number on select
Can I run a select statement and get the row number if the items are sorted?
5 Answers
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Find number of months between two Dates in Ruby on Rails
...is solution does not consider days. The number of months between 28/4/2000 and 1/5/2000 is not 1 month, but 0.
– dgilperez
Aug 19 '13 at 18:39
15
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