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How to clone ArrayList and also clone its contents?
...
You can't do it generically, though. clone() is not part of the Cloneable interface.
– Michael Myers♦
Apr 3 '09 at 20:47
13
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How to skip over an element in .map()?
...nce it has some cost, you can use the more general .reduce(). You can generally express .map() in terms of .reduce:
someArray.map(function(element) {
return transform(element);
});
can be written as
someArray.reduce(function(result, element) {
result.push(transform(element));
return result;
}...
Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_
...AMD documents it and compilers don't expose it.)
(Yes, these instructions all run on the same execution unit).
This dependency doesn't just hold up the 4 popcnts from a single loop iteration. It can carry across loop iterations making it impossible for the processor to parallelize different loop...
What is the real overhead of try/catch in C#?
... to make here:
Firstly, there is little or NO performance penalty in actually having try-catch blocks in your code. This should not be a consideration when trying to avoid having them in your application. The performance hit only comes into play when an exception is thrown.
When an exception is th...
RabbitMQ / AMQP: single queue, multiple consumers for same message?
...e messages? Ie, both consumers get message 1, 2, 3, 4, 5, 6? What is this called in AMQP/RabbitMQ speak? How is it normally configured?
No, not if the consumers are on the same queue. From RabbitMQ's AMQP Concepts guide:
it is important to understand that, in AMQP 0-9-1, messages are load balan...
What is the best data type to use for money in C#?
...d to
floating-point types, the decimal type has more precision and a
smaller range, which makes it appropriate for financial and monetary
calculations.
You can use a decimal as follows:
decimal myMoney = 300.5m;
sh...
Downloading an entire S3 bucket?
...eleased their Command Line Tools, which work much like boto and can be installed using
sudo easy_install awscli
or
sudo pip install awscli
Once installed, you can then simply run:
aws s3 sync s3://<source_bucket> <local_destination>
For example:
aws s3 sync s3://mybucket .
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How to remove all null elements from a ArrayList or String Array?
...
Try:
tourists.removeAll(Collections.singleton(null));
Read the Java API. The code will throw java.lang.UnsupportedOperationException for immutable lists (such as created with Arrays.asList); see this answer for more details.
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What strategies and tools are useful for finding memory leaks in .NET?
... this as the answer because its what worked for me in the end, but I think all of the other answers are very useful. By the way, this tool is more commonly called SciTech's Mem Profiler!
– Scott Langham
Oct 9 '08 at 12:44
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Why is there huge performance hit in 2048x2048 versus 2047x2047 array multiplication?
...he misses on matice1 are not the problem because they are accessed sequentially.
However for matice2 if a full column fits in L2 (i.e when you access matice2[0, 0], matice2[1, 0], matice2[2, 0] ... etc, nothing gets evicted) than there is no problem with cache misses with matice2 either.
Now to go ...