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What's the difference between ConcurrentHashMap and Collections.synchronizedMap(Map)?
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For your needs, use ConcurrentHashMap. It allows concurrent modification of the Map from several threads without the need to block them. Collections.synchronizedMap(map) creates a blocking Map which will degrade performance, albeit ensure consistency (if used properl...
knitr Markdown highlighting in Emacs?
...r the former you need polymode and for the latter markdown.el. Besides, if all you want is to just switch the ESS engine from Sweave to knitr (without highlighting!), there is no need to go through all the complication of this article, just add (setq ess-swv-processor 'knitr) in you init file.
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javax.faces.application.ViewExpiredException: View could not be restored
...ession cookie is not maintained anymore for some reason in browser, or by calling HttpSession#invalidate() in server, or due a server specific bug with session cookies as known in WildFly), then the serialized view state is not available anymore in the session and the enduser will get this exception...
How can I reset or revert a file to a specific revision?
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@aliteralmind: Actually, yes, there's a way to do it: "git log --reverse -1 --ancestry-path yourgitrev..master" and then use the appropriate options to just get the git rev. --ancestry-path will "draw a line" between two commits and -1 will sho...
How can I find out the total physical memory (RAM) of my linux box suitable to be parsed by a shell
...d this recently, and have a simple command to get the total memory size of all memory modules on a system: dmidecode -t 17 | grep "Size.*MB" | awk '{s+=$2} END {print s / 1024}'
– Jonesinator
Jun 18 '14 at 23:53
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how to check the dtype of a column in python pandas
...ions to treat numeric columns and string columns. What I am doing now is really dumb:
6 Answers
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What's the fastest way to merge/join data.frames in R?
...(y) from main.d group by g1, g2"))
)
The outputs from the two benchmark call comparing the merge calculations are:
Joining by: x
test replications elapsed relative user.self sys.self user.child sys.child
3 data.table 1 0.34 1.000000 0.31 0.01 NA NA
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Git ignore file for Xcode projects
...on Apple mailing lists.
Apple continues to add undocumented files, potentially corrupting our live projects. This IMHO is unacceptable, and I've now started logging bugs against it each time they do so. I know they don't care, but maybe it'll shame one of them into treating developers more fairly.
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CSS selector for a checked radio button's label
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@Martin Just in case you are wondering, This won't actually work in your case, since the label still needs to follow the input. The difference between '+' and '~' is whether the label is directly adjacent, or is generally adjecent: whether the label is the next element, or just o...
Resolving conflicts: how to accept “their” changes automatically?
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Use
hg resolve -t internal:other --all
to accept theirs and
hg resolve -t internal:local --all
to accept yours
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