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String concatenation: concat() vs “+” operator
...then throwing it away when you create the final String. In practice memory allocation is surprisingly fast.
Update: As Pawel Adamski notes, performance has changed in more recent HotSpot. javac still produces exactly the same code, but the bytecode compiler cheats. Simple testing entirely fails bec...
Determine the number of lines within a text file
...ne loads the entire contents of the file into an array which means it must allocate at least as much memory as the size of the file. The second merely loops one line at a time so it never has to allocate more than one line's worth of memory at a time. This isn't that important for small files, but f...
How do you convert an entire directory with ffmpeg?
...
And on Windows:
FOR /F "tokens=*" %G IN ('dir /b *.flac') DO ffmpeg -i "%G" -acodec mp3 "%~nG.mp3"
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Explain the concept of a stack frame in a nutshell
...rocessor knows anything about stack, because WE manipulate it via subbing (allocation), pushing and popping. And so here are calling conventions which explain how we should use the stack.
– Victor Polevoy
Apr 18 '18 at 7:18
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parsing JSONP $http.jsonp() response in angular.js
...You still need to set callback in the params:
var params = {
'a': b,
'token_auth': TOKEN,
'callback': 'functionName'
};
$sce.trustAsResourceUrl(url);
$http.jsonp(url, {
params: params
});
Where 'functionName' is a stringified reference to globally defined function. You can define it outs...
What does the “__block” keyword mean?
...and static.[testme] Variables qualified by __block act as if they were in allocated storage and this storage is automatically recovered after last use of said variable. An implementation may choose an optimization where the storage is initially automatic and only "moved" to allocated (heap) storag...
How to port data-only volumes from one host to another?
...-server on a machine you want to copy data from (You'll need the NGROK_AUTHTOKEN which can be obtained from ngrok dashboard):
$ docker run --rm -e NGROK_AUTHTOKEN="$NGROK_AUTHTOKEN" \
--mount source=MY_VOLUME,target=/data,readonly \
quay.io/suda/dvsync-server
Then you can start the dvsync-cli...
What do the plus and minus signs mean in Objective-C next to a method?
...se?
[CustomClass classMethod];
CustomClass *classObject = [[CustomClass alloc] init];
[classObject instanceMethod];
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Shards and replicas in Elasticsearch
...search performance and for fail-over. A replica shard is never going to be allocated on the same node where the related primary is (it would pretty much be like putting a backup on the same disk as the original data).
Back to our example, with 1 replica we'll have the whole index on each node, sinc...
Why was “Avoid Enums Where You Only Need Ints” removed from Android's performance tips?
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TLDR: Dalvik was not good with memory allocation and Enum uses more memory than int. Android Lollipop replaced Dalvik with ART which does not suffer from the same limitations. Thus this recommendation is not relevant anymore.
The long answer:
Wow! 8 years, 5 a...